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/*
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* Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.lang.invoke;
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import java.lang.reflect.*;
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/**
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* This class consists exclusively of static methods that operate on or return
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* method handles. They fall into several categories:
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* <ul>
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* <li>Lookup methods which help create method handles for methods and fields.
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* <li>Combinator methods, which combine or transform pre-existing method handles into new ones.
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* <li>Other factory methods to create method handles that emulate other common JVM operations or control flow patterns.
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* </ul>
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* <p>
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* @author John Rose, JSR 292 EG
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* @since 1.7
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*/
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public class MethodHandles {
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private MethodHandles() { } // do not instantiate
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//// Method handle creation from ordinary methods.
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/**
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* Returns a {@link Lookup lookup object} with
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* full capabilities to emulate all supported bytecode behaviors of the caller.
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* These capabilities include <a href="MethodHandles.Lookup.html#privacc">private access</a> to the caller.
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* Factory methods on the lookup object can create
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* <a href="MethodHandleInfo.html#directmh">direct method handles</a>
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* for any member that the caller has access to via bytecodes,
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* including protected and private fields and methods.
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* This lookup object is a <em>capability</em> which may be delegated to trusted agents.
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* Do not store it in place where untrusted code can access it.
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* <p>
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* This method is caller sensitive, which means that it may return different
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* values to different callers.
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* <p>
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* For any given caller class {@code C}, the lookup object returned by this call
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* has equivalent capabilities to any lookup object
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* supplied by the JVM to the bootstrap method of an
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* <a href="package-summary.html#indyinsn">invokedynamic instruction</a>
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* executing in the same caller class {@code C}.
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* @return a lookup object for the caller of this method, with private access
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*/
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// @CallerSensitive
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public static Lookup lookup() {
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throw new IllegalStateException("Implement me!");
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// return new Lookup(Reflection.getCallerClass());
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}
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/**
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* Returns a {@link Lookup lookup object} which is trusted minimally.
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* It can only be used to create method handles to
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* publicly accessible fields and methods.
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* <p>
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* As a matter of pure convention, the {@linkplain Lookup#lookupClass lookup class}
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* of this lookup object will be {@link java.lang.Object}.
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*
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* <p style="font-size:smaller;">
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* <em>Discussion:</em>
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* The lookup class can be changed to any other class {@code C} using an expression of the form
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* {@link Lookup#in publicLookup().in(C.class)}.
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* Since all classes have equal access to public names,
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* such a change would confer no new access rights.
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* A public lookup object is always subject to
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* <a href="MethodHandles.Lookup.html#secmgr">security manager checks</a>.
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* Also, it cannot access
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* <a href="MethodHandles.Lookup.html#callsens">caller sensitive methods</a>.
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* @return a lookup object which is trusted minimally
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*/
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public static Lookup publicLookup() {
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return Lookup.PUBLIC_LOOKUP;
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}
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/**
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* Performs an unchecked "crack" of a
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* <a href="MethodHandleInfo.html#directmh">direct method handle</a>.
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* The result is as if the user had obtained a lookup object capable enough
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* to crack the target method handle, called
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* {@link java.lang.invoke.MethodHandles.Lookup#revealDirect Lookup.revealDirect}
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* on the target to obtain its symbolic reference, and then called
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* {@link java.lang.invoke.MethodHandleInfo#reflectAs MethodHandleInfo.reflectAs}
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* to resolve the symbolic reference to a member.
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* <p>
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* If there is a security manager, its {@code checkPermission} method
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* is called with a {@code ReflectPermission("suppressAccessChecks")} permission.
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* @param <T> the desired type of the result, either {@link Member} or a subtype
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* @param target a direct method handle to crack into symbolic reference components
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* @param expected a class object representing the desired result type {@code T}
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* @return a reference to the method, constructor, or field object
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* @exception SecurityException if the caller is not privileged to call {@code setAccessible}
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* @exception NullPointerException if either argument is {@code null}
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* @exception IllegalArgumentException if the target is not a direct method handle
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* @exception ClassCastException if the member is not of the expected type
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* @since 1.8
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*/
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public static <T extends Member> T
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reflectAs(Class<T> expected, MethodHandle target) {
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throw new IllegalStateException();
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}
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// Copied from AccessibleObject, as used by Method.setAccessible, etc.:
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// static final private java.security.Permission ACCESS_PERMISSION =
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// new ReflectPermission("suppressAccessChecks");
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static Lookup findFor(Class<?> clazz) {
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Object o = clazz;
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if (o instanceof Class) {
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return new Lookup(clazz, Lookup.ALL_MODES);
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}
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throw new IllegalArgumentException("Expecting class: " + o);
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}
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/**
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* A <em>lookup object</em> is a factory for creating method handles,
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* when the creation requires access checking.
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* Method handles do not perform
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* access checks when they are called, but rather when they are created.
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* Therefore, method handle access
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* restrictions must be enforced when a method handle is created.
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* The caller class against which those restrictions are enforced
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* is known as the {@linkplain #lookupClass lookup class}.
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* <p>
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* A lookup class which needs to create method handles will call
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* {@link MethodHandles#lookup MethodHandles.lookup} to create a factory for itself.
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* When the {@code Lookup} factory object is created, the identity of the lookup class is
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* determined, and securely stored in the {@code Lookup} object.
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* The lookup class (or its delegates) may then use factory methods
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* on the {@code Lookup} object to create method handles for access-checked members.
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* This includes all methods, constructors, and fields which are allowed to the lookup class,
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* even private ones.
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*
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* <h1><a name="lookups"></a>Lookup Factory Methods</h1>
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* The factory methods on a {@code Lookup} object correspond to all major
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* use cases for methods, constructors, and fields.
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* Each method handle created by a factory method is the functional
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* equivalent of a particular <em>bytecode behavior</em>.
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* (Bytecode behaviors are described in section 5.4.3.5 of the Java Virtual Machine Specification.)
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* Here is a summary of the correspondence between these factory methods and
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* the behavior the resulting method handles:
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* <table border=1 cellpadding=5 summary="lookup method behaviors">
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* <tr>
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* <th><a name="equiv"></a>lookup expression</th>
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* <th>member</th>
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* <th>bytecode behavior</th>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#findGetter lookup.findGetter(C.class,"f",FT.class)}</td>
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* <td>{@code FT f;}</td><td>{@code (T) this.f;}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#findStaticGetter lookup.findStaticGetter(C.class,"f",FT.class)}</td>
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* <td>{@code static}<br>{@code FT f;}</td><td>{@code (T) C.f;}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#findSetter lookup.findSetter(C.class,"f",FT.class)}</td>
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* <td>{@code FT f;}</td><td>{@code this.f = x;}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#findStaticSetter lookup.findStaticSetter(C.class,"f",FT.class)}</td>
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* <td>{@code static}<br>{@code FT f;}</td><td>{@code C.f = arg;}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#findVirtual lookup.findVirtual(C.class,"m",MT)}</td>
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* <td>{@code T m(A*);}</td><td>{@code (T) this.m(arg*);}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#findStatic lookup.findStatic(C.class,"m",MT)}</td>
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* <td>{@code static}<br>{@code T m(A*);}</td><td>{@code (T) C.m(arg*);}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#findSpecial lookup.findSpecial(C.class,"m",MT,this.class)}</td>
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* <td>{@code T m(A*);}</td><td>{@code (T) super.m(arg*);}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#findConstructor lookup.findConstructor(C.class,MT)}</td>
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* <td>{@code C(A*);}</td><td>{@code new C(arg*);}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflectGetter lookup.unreflectGetter(aField)}</td>
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* <td>({@code static})?<br>{@code FT f;}</td><td>{@code (FT) aField.get(thisOrNull);}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflectSetter lookup.unreflectSetter(aField)}</td>
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* <td>({@code static})?<br>{@code FT f;}</td><td>{@code aField.set(thisOrNull, arg);}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflect lookup.unreflect(aMethod)}</td>
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* <td>({@code static})?<br>{@code T m(A*);}</td><td>{@code (T) aMethod.invoke(thisOrNull, arg*);}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflectConstructor lookup.unreflectConstructor(aConstructor)}</td>
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* <td>{@code C(A*);}</td><td>{@code (C) aConstructor.newInstance(arg*);}</td>
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* </tr>
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* <tr>
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* <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflect lookup.unreflect(aMethod)}</td>
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* <td>({@code static})?<br>{@code T m(A*);}</td><td>{@code (T) aMethod.invoke(thisOrNull, arg*);}</td>
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* </tr>
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* </table>
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*
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* Here, the type {@code C} is the class or interface being searched for a member,
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* documented as a parameter named {@code refc} in the lookup methods.
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* The method type {@code MT} is composed from the return type {@code T}
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* and the sequence of argument types {@code A*}.
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* The constructor also has a sequence of argument types {@code A*} and
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* is deemed to return the newly-created object of type {@code C}.
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* Both {@code MT} and the field type {@code FT} are documented as a parameter named {@code type}.
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* The formal parameter {@code this} stands for the self-reference of type {@code C};
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* if it is present, it is always the leading argument to the method handle invocation.
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* (In the case of some {@code protected} members, {@code this} may be
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* restricted in type to the lookup class; see below.)
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* The name {@code arg} stands for all the other method handle arguments.
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* In the code examples for the Core Reflection API, the name {@code thisOrNull}
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* stands for a null reference if the accessed method or field is static,
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* and {@code this} otherwise.
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* The names {@code aMethod}, {@code aField}, and {@code aConstructor} stand
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* for reflective objects corresponding to the given members.
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* <p>
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* In cases where the given member is of variable arity (i.e., a method or constructor)
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* the returned method handle will also be of {@linkplain MethodHandle#asVarargsCollector variable arity}.
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* In all other cases, the returned method handle will be of fixed arity.
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* <p style="font-size:smaller;">
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* <em>Discussion:</em>
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* The equivalence between looked-up method handles and underlying
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* class members and bytecode behaviors
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* can break down in a few ways:
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* <ul style="font-size:smaller;">
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* <li>If {@code C} is not symbolically accessible from the lookup class's loader,
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* the lookup can still succeed, even when there is no equivalent
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* Java expression or bytecoded constant.
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* <li>Likewise, if {@code T} or {@code MT}
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* is not symbolically accessible from the lookup class's loader,
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* the lookup can still succeed.
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* For example, lookups for {@code MethodHandle.invokeExact} and
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|
258 |
* {@code MethodHandle.invoke} will always succeed, regardless of requested type.
|
jaroslav@1692
|
259 |
* <li>If there is a security manager installed, it can forbid the lookup
|
jaroslav@1692
|
260 |
* on various grounds (<a href="MethodHandles.Lookup.html#secmgr">see below</a>).
|
jaroslav@1692
|
261 |
* By contrast, the {@code ldc} instruction on a {@code CONSTANT_MethodHandle}
|
jaroslav@1692
|
262 |
* constant is not subject to security manager checks.
|
jaroslav@1692
|
263 |
* <li>If the looked-up method has a
|
jaroslav@1692
|
264 |
* <a href="MethodHandle.html#maxarity">very large arity</a>,
|
jaroslav@1692
|
265 |
* the method handle creation may fail, due to the method handle
|
jaroslav@1692
|
266 |
* type having too many parameters.
|
jaroslav@1692
|
267 |
* </ul>
|
jaroslav@1692
|
268 |
*
|
jaroslav@1692
|
269 |
* <h1><a name="access"></a>Access checking</h1>
|
jaroslav@1692
|
270 |
* Access checks are applied in the factory methods of {@code Lookup},
|
jaroslav@1692
|
271 |
* when a method handle is created.
|
jaroslav@1692
|
272 |
* This is a key difference from the Core Reflection API, since
|
jaroslav@1692
|
273 |
* {@link java.lang.reflect.Method#invoke java.lang.reflect.Method.invoke}
|
jaroslav@1692
|
274 |
* performs access checking against every caller, on every call.
|
jaroslav@1692
|
275 |
* <p>
|
jaroslav@1692
|
276 |
* All access checks start from a {@code Lookup} object, which
|
jaroslav@1692
|
277 |
* compares its recorded lookup class against all requests to
|
jaroslav@1692
|
278 |
* create method handles.
|
jaroslav@1692
|
279 |
* A single {@code Lookup} object can be used to create any number
|
jaroslav@1692
|
280 |
* of access-checked method handles, all checked against a single
|
jaroslav@1692
|
281 |
* lookup class.
|
jaroslav@1692
|
282 |
* <p>
|
jaroslav@1692
|
283 |
* A {@code Lookup} object can be shared with other trusted code,
|
jaroslav@1692
|
284 |
* such as a metaobject protocol.
|
jaroslav@1692
|
285 |
* A shared {@code Lookup} object delegates the capability
|
jaroslav@1692
|
286 |
* to create method handles on private members of the lookup class.
|
jaroslav@1692
|
287 |
* Even if privileged code uses the {@code Lookup} object,
|
jaroslav@1692
|
288 |
* the access checking is confined to the privileges of the
|
jaroslav@1692
|
289 |
* original lookup class.
|
jaroslav@1692
|
290 |
* <p>
|
jaroslav@1692
|
291 |
* A lookup can fail, because
|
jaroslav@1692
|
292 |
* the containing class is not accessible to the lookup class, or
|
jaroslav@1692
|
293 |
* because the desired class member is missing, or because the
|
jaroslav@1692
|
294 |
* desired class member is not accessible to the lookup class, or
|
jaroslav@1692
|
295 |
* because the lookup object is not trusted enough to access the member.
|
jaroslav@1692
|
296 |
* In any of these cases, a {@code ReflectiveOperationException} will be
|
jaroslav@1692
|
297 |
* thrown from the attempted lookup. The exact class will be one of
|
jaroslav@1692
|
298 |
* the following:
|
jaroslav@1692
|
299 |
* <ul>
|
jaroslav@1692
|
300 |
* <li>NoSuchMethodException — if a method is requested but does not exist
|
jaroslav@1692
|
301 |
* <li>NoSuchFieldException — if a field is requested but does not exist
|
jaroslav@1692
|
302 |
* <li>IllegalAccessException — if the member exists but an access check fails
|
jaroslav@1692
|
303 |
* </ul>
|
jaroslav@1692
|
304 |
* <p>
|
jaroslav@1692
|
305 |
* In general, the conditions under which a method handle may be
|
jaroslav@1692
|
306 |
* looked up for a method {@code M} are no more restrictive than the conditions
|
jaroslav@1692
|
307 |
* under which the lookup class could have compiled, verified, and resolved a call to {@code M}.
|
jaroslav@1692
|
308 |
* Where the JVM would raise exceptions like {@code NoSuchMethodError},
|
jaroslav@1692
|
309 |
* a method handle lookup will generally raise a corresponding
|
jaroslav@1692
|
310 |
* checked exception, such as {@code NoSuchMethodException}.
|
jaroslav@1692
|
311 |
* And the effect of invoking the method handle resulting from the lookup
|
jaroslav@1692
|
312 |
* is <a href="MethodHandles.Lookup.html#equiv">exactly equivalent</a>
|
jaroslav@1692
|
313 |
* to executing the compiled, verified, and resolved call to {@code M}.
|
jaroslav@1692
|
314 |
* The same point is true of fields and constructors.
|
jaroslav@1692
|
315 |
* <p style="font-size:smaller;">
|
jaroslav@1692
|
316 |
* <em>Discussion:</em>
|
jaroslav@1692
|
317 |
* Access checks only apply to named and reflected methods,
|
jaroslav@1692
|
318 |
* constructors, and fields.
|
jaroslav@1692
|
319 |
* Other method handle creation methods, such as
|
jaroslav@1692
|
320 |
* {@link MethodHandle#asType MethodHandle.asType},
|
jaroslav@1692
|
321 |
* do not require any access checks, and are used
|
jaroslav@1692
|
322 |
* independently of any {@code Lookup} object.
|
jaroslav@1692
|
323 |
* <p>
|
jaroslav@1692
|
324 |
* If the desired member is {@code protected}, the usual JVM rules apply,
|
jaroslav@1692
|
325 |
* including the requirement that the lookup class must be either be in the
|
jaroslav@1692
|
326 |
* same package as the desired member, or must inherit that member.
|
jaroslav@1692
|
327 |
* (See the Java Virtual Machine Specification, sections 4.9.2, 5.4.3.5, and 6.4.)
|
jaroslav@1692
|
328 |
* In addition, if the desired member is a non-static field or method
|
jaroslav@1692
|
329 |
* in a different package, the resulting method handle may only be applied
|
jaroslav@1692
|
330 |
* to objects of the lookup class or one of its subclasses.
|
jaroslav@1692
|
331 |
* This requirement is enforced by narrowing the type of the leading
|
jaroslav@1692
|
332 |
* {@code this} parameter from {@code C}
|
jaroslav@1692
|
333 |
* (which will necessarily be a superclass of the lookup class)
|
jaroslav@1692
|
334 |
* to the lookup class itself.
|
jaroslav@1692
|
335 |
* <p>
|
jaroslav@1692
|
336 |
* The JVM imposes a similar requirement on {@code invokespecial} instruction,
|
jaroslav@1692
|
337 |
* that the receiver argument must match both the resolved method <em>and</em>
|
jaroslav@1692
|
338 |
* the current class. Again, this requirement is enforced by narrowing the
|
jaroslav@1692
|
339 |
* type of the leading parameter to the resulting method handle.
|
jaroslav@1692
|
340 |
* (See the Java Virtual Machine Specification, section 4.10.1.9.)
|
jaroslav@1692
|
341 |
* <p>
|
jaroslav@1692
|
342 |
* The JVM represents constructors and static initializer blocks as internal methods
|
jaroslav@1692
|
343 |
* with special names ({@code "<init>"} and {@code "<clinit>"}).
|
jaroslav@1692
|
344 |
* The internal syntax of invocation instructions allows them to refer to such internal
|
jaroslav@1692
|
345 |
* methods as if they were normal methods, but the JVM bytecode verifier rejects them.
|
jaroslav@1692
|
346 |
* A lookup of such an internal method will produce a {@code NoSuchMethodException}.
|
jaroslav@1692
|
347 |
* <p>
|
jaroslav@1692
|
348 |
* In some cases, access between nested classes is obtained by the Java compiler by creating
|
jaroslav@1692
|
349 |
* an wrapper method to access a private method of another class
|
jaroslav@1692
|
350 |
* in the same top-level declaration.
|
jaroslav@1692
|
351 |
* For example, a nested class {@code C.D}
|
jaroslav@1692
|
352 |
* can access private members within other related classes such as
|
jaroslav@1692
|
353 |
* {@code C}, {@code C.D.E}, or {@code C.B},
|
jaroslav@1692
|
354 |
* but the Java compiler may need to generate wrapper methods in
|
jaroslav@1692
|
355 |
* those related classes. In such cases, a {@code Lookup} object on
|
jaroslav@1692
|
356 |
* {@code C.E} would be unable to those private members.
|
jaroslav@1692
|
357 |
* A workaround for this limitation is the {@link Lookup#in Lookup.in} method,
|
jaroslav@1692
|
358 |
* which can transform a lookup on {@code C.E} into one on any of those other
|
jaroslav@1692
|
359 |
* classes, without special elevation of privilege.
|
jaroslav@1692
|
360 |
* <p>
|
jaroslav@1692
|
361 |
* The accesses permitted to a given lookup object may be limited,
|
jaroslav@1692
|
362 |
* according to its set of {@link #lookupModes lookupModes},
|
jaroslav@1692
|
363 |
* to a subset of members normally accessible to the lookup class.
|
jaroslav@1692
|
364 |
* For example, the {@link MethodHandles#publicLookup publicLookup}
|
jaroslav@1692
|
365 |
* method produces a lookup object which is only allowed to access
|
jaroslav@1692
|
366 |
* public members in public classes.
|
jaroslav@1692
|
367 |
* The caller sensitive method {@link MethodHandles#lookup lookup}
|
jaroslav@1692
|
368 |
* produces a lookup object with full capabilities relative to
|
jaroslav@1692
|
369 |
* its caller class, to emulate all supported bytecode behaviors.
|
jaroslav@1692
|
370 |
* Also, the {@link Lookup#in Lookup.in} method may produce a lookup object
|
jaroslav@1692
|
371 |
* with fewer access modes than the original lookup object.
|
jaroslav@1692
|
372 |
*
|
jaroslav@1692
|
373 |
* <p style="font-size:smaller;">
|
jaroslav@1692
|
374 |
* <a name="privacc"></a>
|
jaroslav@1692
|
375 |
* <em>Discussion of private access:</em>
|
jaroslav@1692
|
376 |
* We say that a lookup has <em>private access</em>
|
jaroslav@1692
|
377 |
* if its {@linkplain #lookupModes lookup modes}
|
jaroslav@1692
|
378 |
* include the possibility of accessing {@code private} members.
|
jaroslav@1692
|
379 |
* As documented in the relevant methods elsewhere,
|
jaroslav@1692
|
380 |
* only lookups with private access possess the following capabilities:
|
jaroslav@1692
|
381 |
* <ul style="font-size:smaller;">
|
jaroslav@1692
|
382 |
* <li>access private fields, methods, and constructors of the lookup class
|
jaroslav@1692
|
383 |
* <li>create method handles which invoke <a href="MethodHandles.Lookup.html#callsens">caller sensitive</a> methods,
|
jaroslav@1692
|
384 |
* such as {@code Class.forName}
|
jaroslav@1692
|
385 |
* <li>create method handles which {@link Lookup#findSpecial emulate invokespecial} instructions
|
jaroslav@1692
|
386 |
* <li>avoid <a href="MethodHandles.Lookup.html#secmgr">package access checks</a>
|
jaroslav@1692
|
387 |
* for classes accessible to the lookup class
|
jaroslav@1692
|
388 |
* <li>create {@link Lookup#in delegated lookup objects} which have private access to other classes
|
jaroslav@1692
|
389 |
* within the same package member
|
jaroslav@1692
|
390 |
* </ul>
|
jaroslav@1692
|
391 |
* <p style="font-size:smaller;">
|
jaroslav@1692
|
392 |
* Each of these permissions is a consequence of the fact that a lookup object
|
jaroslav@1692
|
393 |
* with private access can be securely traced back to an originating class,
|
jaroslav@1692
|
394 |
* whose <a href="MethodHandles.Lookup.html#equiv">bytecode behaviors</a> and Java language access permissions
|
jaroslav@1692
|
395 |
* can be reliably determined and emulated by method handles.
|
jaroslav@1692
|
396 |
*
|
jaroslav@1692
|
397 |
* <h1><a name="secmgr"></a>Security manager interactions</h1>
|
jaroslav@1692
|
398 |
* Although bytecode instructions can only refer to classes in
|
jaroslav@1692
|
399 |
* a related class loader, this API can search for methods in any
|
jaroslav@1692
|
400 |
* class, as long as a reference to its {@code Class} object is
|
jaroslav@1692
|
401 |
* available. Such cross-loader references are also possible with the
|
jaroslav@1692
|
402 |
* Core Reflection API, and are impossible to bytecode instructions
|
jaroslav@1692
|
403 |
* such as {@code invokestatic} or {@code getfield}.
|
jaroslav@1692
|
404 |
* There is a {@linkplain java.lang.SecurityManager security manager API}
|
jaroslav@1692
|
405 |
* to allow applications to check such cross-loader references.
|
jaroslav@1692
|
406 |
* These checks apply to both the {@code MethodHandles.Lookup} API
|
jaroslav@1692
|
407 |
* and the Core Reflection API
|
jaroslav@1692
|
408 |
* (as found on {@link java.lang.Class Class}).
|
jaroslav@1692
|
409 |
* <p>
|
jaroslav@1692
|
410 |
* If a security manager is present, member lookups are subject to
|
jaroslav@1692
|
411 |
* additional checks.
|
jaroslav@1692
|
412 |
* From one to three calls are made to the security manager.
|
jaroslav@1692
|
413 |
* Any of these calls can refuse access by throwing a
|
jaroslav@1692
|
414 |
* {@link java.lang.SecurityException SecurityException}.
|
jaroslav@1692
|
415 |
* Define {@code smgr} as the security manager,
|
jaroslav@1692
|
416 |
* {@code lookc} as the lookup class of the current lookup object,
|
jaroslav@1692
|
417 |
* {@code refc} as the containing class in which the member
|
jaroslav@1692
|
418 |
* is being sought, and {@code defc} as the class in which the
|
jaroslav@1692
|
419 |
* member is actually defined.
|
jaroslav@1692
|
420 |
* The value {@code lookc} is defined as <em>not present</em>
|
jaroslav@1692
|
421 |
* if the current lookup object does not have
|
jaroslav@1692
|
422 |
* <a href="MethodHandles.Lookup.html#privacc">private access</a>.
|
jaroslav@1692
|
423 |
* The calls are made according to the following rules:
|
jaroslav@1692
|
424 |
* <ul>
|
jaroslav@1692
|
425 |
* <li><b>Step 1:</b>
|
jaroslav@1692
|
426 |
* If {@code lookc} is not present, or if its class loader is not
|
jaroslav@1692
|
427 |
* the same as or an ancestor of the class loader of {@code refc},
|
jaroslav@1692
|
428 |
* then {@link SecurityManager#checkPackageAccess
|
jaroslav@1692
|
429 |
* smgr.checkPackageAccess(refcPkg)} is called,
|
jaroslav@1692
|
430 |
* where {@code refcPkg} is the package of {@code refc}.
|
jaroslav@1692
|
431 |
* <li><b>Step 2:</b>
|
jaroslav@1692
|
432 |
* If the retrieved member is not public and
|
jaroslav@1692
|
433 |
* {@code lookc} is not present, then
|
jaroslav@1692
|
434 |
* {@link SecurityManager#checkPermission smgr.checkPermission}
|
jaroslav@1692
|
435 |
* with {@code RuntimePermission("accessDeclaredMembers")} is called.
|
jaroslav@1692
|
436 |
* <li><b>Step 3:</b>
|
jaroslav@1692
|
437 |
* If the retrieved member is not public,
|
jaroslav@1692
|
438 |
* and if {@code lookc} is not present,
|
jaroslav@1692
|
439 |
* and if {@code defc} and {@code refc} are different,
|
jaroslav@1692
|
440 |
* then {@link SecurityManager#checkPackageAccess
|
jaroslav@1692
|
441 |
* smgr.checkPackageAccess(defcPkg)} is called,
|
jaroslav@1692
|
442 |
* where {@code defcPkg} is the package of {@code defc}.
|
jaroslav@1692
|
443 |
* </ul>
|
jaroslav@1692
|
444 |
* Security checks are performed after other access checks have passed.
|
jaroslav@1692
|
445 |
* Therefore, the above rules presuppose a member that is public,
|
jaroslav@1692
|
446 |
* or else that is being accessed from a lookup class that has
|
jaroslav@1692
|
447 |
* rights to access the member.
|
jaroslav@1692
|
448 |
*
|
jaroslav@1692
|
449 |
* <h1><a name="callsens"></a>Caller sensitive methods</h1>
|
jaroslav@1692
|
450 |
* A small number of Java methods have a special property called caller sensitivity.
|
jaroslav@1692
|
451 |
* A <em>caller-sensitive</em> method can behave differently depending on the
|
jaroslav@1692
|
452 |
* identity of its immediate caller.
|
jaroslav@1692
|
453 |
* <p>
|
jaroslav@1692
|
454 |
* If a method handle for a caller-sensitive method is requested,
|
jaroslav@1692
|
455 |
* the general rules for <a href="MethodHandles.Lookup.html#equiv">bytecode behaviors</a> apply,
|
jaroslav@1692
|
456 |
* but they take account of the lookup class in a special way.
|
jaroslav@1692
|
457 |
* The resulting method handle behaves as if it were called
|
jaroslav@1692
|
458 |
* from an instruction contained in the lookup class,
|
jaroslav@1692
|
459 |
* so that the caller-sensitive method detects the lookup class.
|
jaroslav@1692
|
460 |
* (By contrast, the invoker of the method handle is disregarded.)
|
jaroslav@1692
|
461 |
* Thus, in the case of caller-sensitive methods,
|
jaroslav@1692
|
462 |
* different lookup classes may give rise to
|
jaroslav@1692
|
463 |
* differently behaving method handles.
|
jaroslav@1692
|
464 |
* <p>
|
jaroslav@1692
|
465 |
* In cases where the lookup object is
|
jaroslav@1692
|
466 |
* {@link MethodHandles#publicLookup() publicLookup()},
|
jaroslav@1692
|
467 |
* or some other lookup object without
|
jaroslav@1692
|
468 |
* <a href="MethodHandles.Lookup.html#privacc">private access</a>,
|
jaroslav@1692
|
469 |
* the lookup class is disregarded.
|
jaroslav@1692
|
470 |
* In such cases, no caller-sensitive method handle can be created,
|
jaroslav@1692
|
471 |
* access is forbidden, and the lookup fails with an
|
jaroslav@1692
|
472 |
* {@code IllegalAccessException}.
|
jaroslav@1692
|
473 |
* <p style="font-size:smaller;">
|
jaroslav@1692
|
474 |
* <em>Discussion:</em>
|
jaroslav@1692
|
475 |
* For example, the caller-sensitive method
|
jaroslav@1692
|
476 |
* {@link java.lang.Class#forName(String) Class.forName(x)}
|
jaroslav@1692
|
477 |
* can return varying classes or throw varying exceptions,
|
jaroslav@1692
|
478 |
* depending on the class loader of the class that calls it.
|
jaroslav@1692
|
479 |
* A public lookup of {@code Class.forName} will fail, because
|
jaroslav@1692
|
480 |
* there is no reasonable way to determine its bytecode behavior.
|
jaroslav@1692
|
481 |
* <p style="font-size:smaller;">
|
jaroslav@1692
|
482 |
* If an application caches method handles for broad sharing,
|
jaroslav@1692
|
483 |
* it should use {@code publicLookup()} to create them.
|
jaroslav@1692
|
484 |
* If there is a lookup of {@code Class.forName}, it will fail,
|
jaroslav@1692
|
485 |
* and the application must take appropriate action in that case.
|
jaroslav@1692
|
486 |
* It may be that a later lookup, perhaps during the invocation of a
|
jaroslav@1692
|
487 |
* bootstrap method, can incorporate the specific identity
|
jaroslav@1692
|
488 |
* of the caller, making the method accessible.
|
jaroslav@1692
|
489 |
* <p style="font-size:smaller;">
|
jaroslav@1692
|
490 |
* The function {@code MethodHandles.lookup} is caller sensitive
|
jaroslav@1692
|
491 |
* so that there can be a secure foundation for lookups.
|
jaroslav@1692
|
492 |
* Nearly all other methods in the JSR 292 API rely on lookup
|
jaroslav@1692
|
493 |
* objects to check access requests.
|
jaroslav@1692
|
494 |
*/
|
jaroslav@1692
|
495 |
public static final
|
jaroslav@1692
|
496 |
class Lookup {
|
jaroslav@1692
|
497 |
/** The class on behalf of whom the lookup is being performed. */
|
jaroslav@1692
|
498 |
private final Class<?> lookupClass;
|
jaroslav@1692
|
499 |
|
jaroslav@1692
|
500 |
/** The allowed sorts of members which may be looked up (PUBLIC, etc.). */
|
jaroslav@1692
|
501 |
private final int allowedModes;
|
jaroslav@1692
|
502 |
|
jaroslav@1692
|
503 |
/** A single-bit mask representing {@code public} access,
|
jaroslav@1692
|
504 |
* which may contribute to the result of {@link #lookupModes lookupModes}.
|
jaroslav@1692
|
505 |
* The value, {@code 0x01}, happens to be the same as the value of the
|
jaroslav@1692
|
506 |
* {@code public} {@linkplain java.lang.reflect.Modifier#PUBLIC modifier bit}.
|
jaroslav@1692
|
507 |
*/
|
jaroslav@1692
|
508 |
public static final int PUBLIC = Modifier.PUBLIC;
|
jaroslav@1692
|
509 |
|
jaroslav@1692
|
510 |
/** A single-bit mask representing {@code private} access,
|
jaroslav@1692
|
511 |
* which may contribute to the result of {@link #lookupModes lookupModes}.
|
jaroslav@1692
|
512 |
* The value, {@code 0x02}, happens to be the same as the value of the
|
jaroslav@1692
|
513 |
* {@code private} {@linkplain java.lang.reflect.Modifier#PRIVATE modifier bit}.
|
jaroslav@1692
|
514 |
*/
|
jaroslav@1692
|
515 |
public static final int PRIVATE = Modifier.PRIVATE;
|
jaroslav@1692
|
516 |
|
jaroslav@1692
|
517 |
/** A single-bit mask representing {@code protected} access,
|
jaroslav@1692
|
518 |
* which may contribute to the result of {@link #lookupModes lookupModes}.
|
jaroslav@1692
|
519 |
* The value, {@code 0x04}, happens to be the same as the value of the
|
jaroslav@1692
|
520 |
* {@code protected} {@linkplain java.lang.reflect.Modifier#PROTECTED modifier bit}.
|
jaroslav@1692
|
521 |
*/
|
jaroslav@1692
|
522 |
public static final int PROTECTED = Modifier.PROTECTED;
|
jaroslav@1692
|
523 |
|
jaroslav@1692
|
524 |
/** A single-bit mask representing {@code package} access (default access),
|
jaroslav@1692
|
525 |
* which may contribute to the result of {@link #lookupModes lookupModes}.
|
jaroslav@1692
|
526 |
* The value is {@code 0x08}, which does not correspond meaningfully to
|
jaroslav@1692
|
527 |
* any particular {@linkplain java.lang.reflect.Modifier modifier bit}.
|
jaroslav@1692
|
528 |
*/
|
jaroslav@1692
|
529 |
public static final int PACKAGE = Modifier.STATIC;
|
jaroslav@1692
|
530 |
|
jaroslav@1692
|
531 |
private static final int ALL_MODES = (PUBLIC | PRIVATE | PROTECTED | PACKAGE);
|
jaroslav@1692
|
532 |
private static final int TRUSTED = -1;
|
jaroslav@1692
|
533 |
|
jaroslav@1692
|
534 |
private static int fixmods(int mods) {
|
jaroslav@1692
|
535 |
mods &= (ALL_MODES - PACKAGE);
|
jaroslav@1692
|
536 |
return (mods != 0) ? mods : PACKAGE;
|
jaroslav@1692
|
537 |
}
|
jaroslav@1692
|
538 |
|
jaroslav@1692
|
539 |
/** Tells which class is performing the lookup. It is this class against
|
jaroslav@1692
|
540 |
* which checks are performed for visibility and access permissions.
|
jaroslav@1692
|
541 |
* <p>
|
jaroslav@1692
|
542 |
* The class implies a maximum level of access permission,
|
jaroslav@1692
|
543 |
* but the permissions may be additionally limited by the bitmask
|
jaroslav@1692
|
544 |
* {@link #lookupModes lookupModes}, which controls whether non-public members
|
jaroslav@1692
|
545 |
* can be accessed.
|
jaroslav@1692
|
546 |
* @return the lookup class, on behalf of which this lookup object finds members
|
jaroslav@1692
|
547 |
*/
|
jaroslav@1692
|
548 |
public Class<?> lookupClass() {
|
jaroslav@1692
|
549 |
return lookupClass;
|
jaroslav@1692
|
550 |
}
|
jaroslav@1692
|
551 |
|
jaroslav@1692
|
552 |
// This is just for calling out to MethodHandleImpl.
|
jaroslav@1692
|
553 |
private Class<?> lookupClassOrNull() {
|
jaroslav@1692
|
554 |
return (allowedModes == TRUSTED) ? null : lookupClass;
|
jaroslav@1692
|
555 |
}
|
jaroslav@1692
|
556 |
|
jaroslav@1692
|
557 |
/** Tells which access-protection classes of members this lookup object can produce.
|
jaroslav@1692
|
558 |
* The result is a bit-mask of the bits
|
jaroslav@1692
|
559 |
* {@linkplain #PUBLIC PUBLIC (0x01)},
|
jaroslav@1692
|
560 |
* {@linkplain #PRIVATE PRIVATE (0x02)},
|
jaroslav@1692
|
561 |
* {@linkplain #PROTECTED PROTECTED (0x04)},
|
jaroslav@1692
|
562 |
* and {@linkplain #PACKAGE PACKAGE (0x08)}.
|
jaroslav@1692
|
563 |
* <p>
|
jaroslav@1692
|
564 |
* A freshly-created lookup object
|
jaroslav@1692
|
565 |
* on the {@linkplain java.lang.invoke.MethodHandles#lookup() caller's class}
|
jaroslav@1692
|
566 |
* has all possible bits set, since the caller class can access all its own members.
|
jaroslav@1692
|
567 |
* A lookup object on a new lookup class
|
jaroslav@1692
|
568 |
* {@linkplain java.lang.invoke.MethodHandles.Lookup#in created from a previous lookup object}
|
jaroslav@1692
|
569 |
* may have some mode bits set to zero.
|
jaroslav@1692
|
570 |
* The purpose of this is to restrict access via the new lookup object,
|
jaroslav@1692
|
571 |
* so that it can access only names which can be reached by the original
|
jaroslav@1692
|
572 |
* lookup object, and also by the new lookup class.
|
jaroslav@1692
|
573 |
* @return the lookup modes, which limit the kinds of access performed by this lookup object
|
jaroslav@1692
|
574 |
*/
|
jaroslav@1692
|
575 |
public int lookupModes() {
|
jaroslav@1692
|
576 |
return allowedModes & ALL_MODES;
|
jaroslav@1692
|
577 |
}
|
jaroslav@1692
|
578 |
|
jaroslav@1692
|
579 |
/** Embody the current class (the lookupClass) as a lookup class
|
jaroslav@1692
|
580 |
* for method handle creation.
|
jaroslav@1692
|
581 |
* Must be called by from a method in this package,
|
jaroslav@1692
|
582 |
* which in turn is called by a method not in this package.
|
jaroslav@1692
|
583 |
*/
|
jaroslav@1692
|
584 |
Lookup(Class<?> lookupClass) {
|
jaroslav@1692
|
585 |
this(lookupClass, ALL_MODES);
|
jaroslav@1692
|
586 |
// make sure we haven't accidentally picked up a privileged class:
|
jaroslav@1692
|
587 |
}
|
jaroslav@1692
|
588 |
|
jaroslav@1692
|
589 |
private Lookup(Class<?> lookupClass, int allowedModes) {
|
jaroslav@1692
|
590 |
this.lookupClass = lookupClass;
|
jaroslav@1692
|
591 |
this.allowedModes = allowedModes;
|
jaroslav@1692
|
592 |
}
|
jaroslav@1692
|
593 |
|
jaroslav@1692
|
594 |
/**
|
jaroslav@1692
|
595 |
* Creates a lookup on the specified new lookup class.
|
jaroslav@1692
|
596 |
* The resulting object will report the specified
|
jaroslav@1692
|
597 |
* class as its own {@link #lookupClass lookupClass}.
|
jaroslav@1692
|
598 |
* <p>
|
jaroslav@1692
|
599 |
* However, the resulting {@code Lookup} object is guaranteed
|
jaroslav@1692
|
600 |
* to have no more access capabilities than the original.
|
jaroslav@1692
|
601 |
* In particular, access capabilities can be lost as follows:<ul>
|
jaroslav@1692
|
602 |
* <li>If the new lookup class differs from the old one,
|
jaroslav@1692
|
603 |
* protected members will not be accessible by virtue of inheritance.
|
jaroslav@1692
|
604 |
* (Protected members may continue to be accessible because of package sharing.)
|
jaroslav@1692
|
605 |
* <li>If the new lookup class is in a different package
|
jaroslav@1692
|
606 |
* than the old one, protected and default (package) members will not be accessible.
|
jaroslav@1692
|
607 |
* <li>If the new lookup class is not within the same package member
|
jaroslav@1692
|
608 |
* as the old one, private members will not be accessible.
|
jaroslav@1692
|
609 |
* <li>If the new lookup class is not accessible to the old lookup class,
|
jaroslav@1692
|
610 |
* then no members, not even public members, will be accessible.
|
jaroslav@1692
|
611 |
* (In all other cases, public members will continue to be accessible.)
|
jaroslav@1692
|
612 |
* </ul>
|
jaroslav@1692
|
613 |
*
|
jaroslav@1692
|
614 |
* @param requestedLookupClass the desired lookup class for the new lookup object
|
jaroslav@1692
|
615 |
* @return a lookup object which reports the desired lookup class
|
jaroslav@1692
|
616 |
* @throws NullPointerException if the argument is null
|
jaroslav@1692
|
617 |
*/
|
jaroslav@1692
|
618 |
public Lookup in(Class<?> requestedLookupClass) {
|
jaroslav@1692
|
619 |
throw new IllegalStateException();
|
jaroslav@1692
|
620 |
}
|
jaroslav@1692
|
621 |
|
jaroslav@1692
|
622 |
/** Version of lookup which is trusted minimally.
|
jaroslav@1692
|
623 |
* It can only be used to create method handles to
|
jaroslav@1692
|
624 |
* publicly accessible members.
|
jaroslav@1692
|
625 |
*/
|
jaroslav@1692
|
626 |
static final Lookup PUBLIC_LOOKUP = new Lookup(Object.class, PUBLIC);
|
jaroslav@1692
|
627 |
|
jaroslav@1692
|
628 |
/** Package-private version of lookup which is trusted. */
|
jaroslav@1692
|
629 |
static final Lookup IMPL_LOOKUP = new Lookup(Object.class, TRUSTED);
|
jaroslav@1692
|
630 |
|
jaroslav@1692
|
631 |
/**
|
jaroslav@1692
|
632 |
* Displays the name of the class from which lookups are to be made.
|
jaroslav@1692
|
633 |
* (The name is the one reported by {@link java.lang.Class#getName() Class.getName}.)
|
jaroslav@1692
|
634 |
* If there are restrictions on the access permitted to this lookup,
|
jaroslav@1692
|
635 |
* this is indicated by adding a suffix to the class name, consisting
|
jaroslav@1692
|
636 |
* of a slash and a keyword. The keyword represents the strongest
|
jaroslav@1692
|
637 |
* allowed access, and is chosen as follows:
|
jaroslav@1692
|
638 |
* <ul>
|
jaroslav@1692
|
639 |
* <li>If no access is allowed, the suffix is "/noaccess".
|
jaroslav@1692
|
640 |
* <li>If only public access is allowed, the suffix is "/public".
|
jaroslav@1692
|
641 |
* <li>If only public and package access are allowed, the suffix is "/package".
|
jaroslav@1692
|
642 |
* <li>If only public, package, and private access are allowed, the suffix is "/private".
|
jaroslav@1692
|
643 |
* </ul>
|
jaroslav@1692
|
644 |
* If none of the above cases apply, it is the case that full
|
jaroslav@1692
|
645 |
* access (public, package, private, and protected) is allowed.
|
jaroslav@1692
|
646 |
* In this case, no suffix is added.
|
jaroslav@1692
|
647 |
* This is true only of an object obtained originally from
|
jaroslav@1692
|
648 |
* {@link java.lang.invoke.MethodHandles#lookup MethodHandles.lookup}.
|
jaroslav@1692
|
649 |
* Objects created by {@link java.lang.invoke.MethodHandles.Lookup#in Lookup.in}
|
jaroslav@1692
|
650 |
* always have restricted access, and will display a suffix.
|
jaroslav@1692
|
651 |
* <p>
|
jaroslav@1692
|
652 |
* (It may seem strange that protected access should be
|
jaroslav@1692
|
653 |
* stronger than private access. Viewed independently from
|
jaroslav@1692
|
654 |
* package access, protected access is the first to be lost,
|
jaroslav@1692
|
655 |
* because it requires a direct subclass relationship between
|
jaroslav@1692
|
656 |
* caller and callee.)
|
jaroslav@1692
|
657 |
* @see #in
|
jaroslav@1692
|
658 |
*/
|
jaroslav@1692
|
659 |
@Override
|
jaroslav@1692
|
660 |
public String toString() {
|
jaroslav@1692
|
661 |
String cname = lookupClass.getName();
|
jaroslav@1692
|
662 |
switch (allowedModes) {
|
jaroslav@1692
|
663 |
case 0: // no privileges
|
jaroslav@1692
|
664 |
return cname + "/noaccess";
|
jaroslav@1692
|
665 |
case PUBLIC:
|
jaroslav@1692
|
666 |
return cname + "/public";
|
jaroslav@1692
|
667 |
case PUBLIC|PACKAGE:
|
jaroslav@1692
|
668 |
return cname + "/package";
|
jaroslav@1692
|
669 |
case ALL_MODES & ~PROTECTED:
|
jaroslav@1692
|
670 |
return cname + "/private";
|
jaroslav@1692
|
671 |
case ALL_MODES:
|
jaroslav@1692
|
672 |
return cname;
|
jaroslav@1692
|
673 |
case TRUSTED:
|
jaroslav@1692
|
674 |
return "/trusted"; // internal only; not exported
|
jaroslav@1692
|
675 |
default: // Should not happen, but it's a bitfield...
|
jaroslav@1692
|
676 |
cname = cname + "/" + Integer.toHexString(allowedModes);
|
jaroslav@1692
|
677 |
assert(false) : cname;
|
jaroslav@1692
|
678 |
return cname;
|
jaroslav@1692
|
679 |
}
|
jaroslav@1692
|
680 |
}
|
jaroslav@1692
|
681 |
|
jaroslav@1692
|
682 |
/**
|
jaroslav@1692
|
683 |
* Produces a method handle for a static method.
|
jaroslav@1692
|
684 |
* The type of the method handle will be that of the method.
|
jaroslav@1692
|
685 |
* (Since static methods do not take receivers, there is no
|
jaroslav@1692
|
686 |
* additional receiver argument inserted into the method handle type,
|
jaroslav@1692
|
687 |
* as there would be with {@link #findVirtual findVirtual} or {@link #findSpecial findSpecial}.)
|
jaroslav@1692
|
688 |
* The method and all its argument types must be accessible to the lookup object.
|
jaroslav@1692
|
689 |
* <p>
|
jaroslav@1692
|
690 |
* The returned method handle will have
|
jaroslav@1692
|
691 |
* {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if
|
jaroslav@1692
|
692 |
* the method's variable arity modifier bit ({@code 0x0080}) is set.
|
jaroslav@1692
|
693 |
* <p>
|
jaroslav@1692
|
694 |
* If the returned method handle is invoked, the method's class will
|
jaroslav@1692
|
695 |
* be initialized, if it has not already been initialized.
|
jaroslav@1692
|
696 |
* <p><b>Example:</b>
|
jaroslav@1692
|
697 |
* <blockquote><pre>{@code
|
jaroslav@1692
|
698 |
import static java.lang.invoke.MethodHandles.*;
|
jaroslav@1692
|
699 |
import static java.lang.invoke.MethodType.*;
|
jaroslav@1692
|
700 |
...
|
jaroslav@1692
|
701 |
MethodHandle MH_asList = publicLookup().findStatic(Arrays.class,
|
jaroslav@1692
|
702 |
"asList", methodType(List.class, Object[].class));
|
jaroslav@1692
|
703 |
assertEquals("[x, y]", MH_asList.invoke("x", "y").toString());
|
jaroslav@1692
|
704 |
* }</pre></blockquote>
|
jaroslav@1692
|
705 |
* @param refc the class from which the method is accessed
|
jaroslav@1692
|
706 |
* @param name the name of the method
|
jaroslav@1692
|
707 |
* @param type the type of the method
|
jaroslav@1692
|
708 |
* @return the desired method handle
|
jaroslav@1692
|
709 |
* @throws NoSuchMethodException if the method does not exist
|
jaroslav@1692
|
710 |
* @throws IllegalAccessException if access checking fails,
|
jaroslav@1692
|
711 |
* or if the method is not {@code static},
|
jaroslav@1692
|
712 |
* or if the method's variable arity modifier bit
|
jaroslav@1692
|
713 |
* is set and {@code asVarargsCollector} fails
|
jaroslav@1692
|
714 |
* @exception SecurityException if a security manager is present and it
|
jaroslav@1692
|
715 |
* <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
|
jaroslav@1692
|
716 |
* @throws NullPointerException if any argument is null
|
jaroslav@1692
|
717 |
*/
|
jaroslav@1692
|
718 |
public
|
jaroslav@1692
|
719 |
MethodHandle findStatic(Class<?> refc, String name, MethodType type) throws NoSuchMethodException, IllegalAccessException {
|
jaroslav@1692
|
720 |
throw new IllegalStateException();
|
jaroslav@1692
|
721 |
}
|
jaroslav@1692
|
722 |
|
jaroslav@1692
|
723 |
/**
|
jaroslav@1692
|
724 |
* Produces a method handle for a virtual method.
|
jaroslav@1692
|
725 |
* The type of the method handle will be that of the method,
|
jaroslav@1692
|
726 |
* with the receiver type (usually {@code refc}) prepended.
|
jaroslav@1692
|
727 |
* The method and all its argument types must be accessible to the lookup object.
|
jaroslav@1692
|
728 |
* <p>
|
jaroslav@1692
|
729 |
* When called, the handle will treat the first argument as a receiver
|
jaroslav@1692
|
730 |
* and dispatch on the receiver's type to determine which method
|
jaroslav@1692
|
731 |
* implementation to enter.
|
jaroslav@1692
|
732 |
* (The dispatching action is identical with that performed by an
|
jaroslav@1692
|
733 |
* {@code invokevirtual} or {@code invokeinterface} instruction.)
|
jaroslav@1692
|
734 |
* <p>
|
jaroslav@1692
|
735 |
* The first argument will be of type {@code refc} if the lookup
|
jaroslav@1692
|
736 |
* class has full privileges to access the member. Otherwise
|
jaroslav@1692
|
737 |
* the member must be {@code protected} and the first argument
|
jaroslav@1692
|
738 |
* will be restricted in type to the lookup class.
|
jaroslav@1692
|
739 |
* <p>
|
jaroslav@1692
|
740 |
* The returned method handle will have
|
jaroslav@1692
|
741 |
* {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if
|
jaroslav@1692
|
742 |
* the method's variable arity modifier bit ({@code 0x0080}) is set.
|
jaroslav@1692
|
743 |
* <p>
|
jaroslav@1692
|
744 |
* Because of the general <a href="MethodHandles.Lookup.html#equiv">equivalence</a> between {@code invokevirtual}
|
jaroslav@1692
|
745 |
* instructions and method handles produced by {@code findVirtual},
|
jaroslav@1692
|
746 |
* if the class is {@code MethodHandle} and the name string is
|
jaroslav@1692
|
747 |
* {@code invokeExact} or {@code invoke}, the resulting
|
jaroslav@1692
|
748 |
* method handle is equivalent to one produced by
|
jaroslav@1692
|
749 |
* {@link java.lang.invoke.MethodHandles#exactInvoker MethodHandles.exactInvoker} or
|
jaroslav@1692
|
750 |
* {@link java.lang.invoke.MethodHandles#invoker MethodHandles.invoker}
|
jaroslav@1692
|
751 |
* with the same {@code type} argument.
|
jaroslav@1692
|
752 |
*
|
jaroslav@1692
|
753 |
* <b>Example:</b>
|
jaroslav@1692
|
754 |
* <blockquote><pre>{@code
|
jaroslav@1692
|
755 |
import static java.lang.invoke.MethodHandles.*;
|
jaroslav@1692
|
756 |
import static java.lang.invoke.MethodType.*;
|
jaroslav@1692
|
757 |
...
|
jaroslav@1692
|
758 |
MethodHandle MH_concat = publicLookup().findVirtual(String.class,
|
jaroslav@1692
|
759 |
"concat", methodType(String.class, String.class));
|
jaroslav@1692
|
760 |
MethodHandle MH_hashCode = publicLookup().findVirtual(Object.class,
|
jaroslav@1692
|
761 |
"hashCode", methodType(int.class));
|
jaroslav@1692
|
762 |
MethodHandle MH_hashCode_String = publicLookup().findVirtual(String.class,
|
jaroslav@1692
|
763 |
"hashCode", methodType(int.class));
|
jaroslav@1692
|
764 |
assertEquals("xy", (String) MH_concat.invokeExact("x", "y"));
|
jaroslav@1692
|
765 |
assertEquals("xy".hashCode(), (int) MH_hashCode.invokeExact((Object)"xy"));
|
jaroslav@1692
|
766 |
assertEquals("xy".hashCode(), (int) MH_hashCode_String.invokeExact("xy"));
|
jaroslav@1692
|
767 |
// interface method:
|
jaroslav@1692
|
768 |
MethodHandle MH_subSequence = publicLookup().findVirtual(CharSequence.class,
|
jaroslav@1692
|
769 |
"subSequence", methodType(CharSequence.class, int.class, int.class));
|
jaroslav@1692
|
770 |
assertEquals("def", MH_subSequence.invoke("abcdefghi", 3, 6).toString());
|
jaroslav@1692
|
771 |
// constructor "internal method" must be accessed differently:
|
jaroslav@1692
|
772 |
MethodType MT_newString = methodType(void.class); //()V for new String()
|
jaroslav@1692
|
773 |
try { assertEquals("impossible", lookup()
|
jaroslav@1692
|
774 |
.findVirtual(String.class, "<init>", MT_newString));
|
jaroslav@1692
|
775 |
} catch (NoSuchMethodException ex) { } // OK
|
jaroslav@1692
|
776 |
MethodHandle MH_newString = publicLookup()
|
jaroslav@1692
|
777 |
.findConstructor(String.class, MT_newString);
|
jaroslav@1692
|
778 |
assertEquals("", (String) MH_newString.invokeExact());
|
jaroslav@1692
|
779 |
* }</pre></blockquote>
|
jaroslav@1692
|
780 |
*
|
jaroslav@1692
|
781 |
* @param refc the class or interface from which the method is accessed
|
jaroslav@1692
|
782 |
* @param name the name of the method
|
jaroslav@1692
|
783 |
* @param type the type of the method, with the receiver argument omitted
|
jaroslav@1692
|
784 |
* @return the desired method handle
|
jaroslav@1692
|
785 |
* @throws NoSuchMethodException if the method does not exist
|
jaroslav@1692
|
786 |
* @throws IllegalAccessException if access checking fails,
|
jaroslav@1692
|
787 |
* or if the method is {@code static}
|
jaroslav@1692
|
788 |
* or if the method's variable arity modifier bit
|
jaroslav@1692
|
789 |
* is set and {@code asVarargsCollector} fails
|
jaroslav@1692
|
790 |
* @exception SecurityException if a security manager is present and it
|
jaroslav@1692
|
791 |
* <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
|
jaroslav@1692
|
792 |
* @throws NullPointerException if any argument is null
|
jaroslav@1692
|
793 |
*/
|
jaroslav@1692
|
794 |
public MethodHandle findVirtual(Class<?> refc, String name, MethodType type) throws NoSuchMethodException, IllegalAccessException {
|
jaroslav@1692
|
795 |
throw new IllegalStateException();
|
jaroslav@1692
|
796 |
}
|
jaroslav@1692
|
797 |
|
jaroslav@1692
|
798 |
/**
|
jaroslav@1692
|
799 |
* Produces a method handle which creates an object and initializes it, using
|
jaroslav@1692
|
800 |
* the constructor of the specified type.
|
jaroslav@1692
|
801 |
* The parameter types of the method handle will be those of the constructor,
|
jaroslav@1692
|
802 |
* while the return type will be a reference to the constructor's class.
|
jaroslav@1692
|
803 |
* The constructor and all its argument types must be accessible to the lookup object.
|
jaroslav@1692
|
804 |
* <p>
|
jaroslav@1692
|
805 |
* The requested type must have a return type of {@code void}.
|
jaroslav@1692
|
806 |
* (This is consistent with the JVM's treatment of constructor type descriptors.)
|
jaroslav@1692
|
807 |
* <p>
|
jaroslav@1692
|
808 |
* The returned method handle will have
|
jaroslav@1692
|
809 |
* {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if
|
jaroslav@1692
|
810 |
* the constructor's variable arity modifier bit ({@code 0x0080}) is set.
|
jaroslav@1692
|
811 |
* <p>
|
jaroslav@1692
|
812 |
* If the returned method handle is invoked, the constructor's class will
|
jaroslav@1692
|
813 |
* be initialized, if it has not already been initialized.
|
jaroslav@1692
|
814 |
* <p><b>Example:</b>
|
jaroslav@1692
|
815 |
* <blockquote><pre>{@code
|
jaroslav@1692
|
816 |
import static java.lang.invoke.MethodHandles.*;
|
jaroslav@1692
|
817 |
import static java.lang.invoke.MethodType.*;
|
jaroslav@1692
|
818 |
...
|
jaroslav@1692
|
819 |
MethodHandle MH_newArrayList = publicLookup().findConstructor(
|
jaroslav@1692
|
820 |
ArrayList.class, methodType(void.class, Collection.class));
|
jaroslav@1692
|
821 |
Collection orig = Arrays.asList("x", "y");
|
jaroslav@1692
|
822 |
Collection copy = (ArrayList) MH_newArrayList.invokeExact(orig);
|
jaroslav@1692
|
823 |
assert(orig != copy);
|
jaroslav@1692
|
824 |
assertEquals(orig, copy);
|
jaroslav@1692
|
825 |
// a variable-arity constructor:
|
jaroslav@1692
|
826 |
MethodHandle MH_newProcessBuilder = publicLookup().findConstructor(
|
jaroslav@1692
|
827 |
ProcessBuilder.class, methodType(void.class, String[].class));
|
jaroslav@1692
|
828 |
ProcessBuilder pb = (ProcessBuilder)
|
jaroslav@1692
|
829 |
MH_newProcessBuilder.invoke("x", "y", "z");
|
jaroslav@1692
|
830 |
assertEquals("[x, y, z]", pb.command().toString());
|
jaroslav@1692
|
831 |
* }</pre></blockquote>
|
jaroslav@1692
|
832 |
* @param refc the class or interface from which the method is accessed
|
jaroslav@1692
|
833 |
* @param type the type of the method, with the receiver argument omitted, and a void return type
|
jaroslav@1692
|
834 |
* @return the desired method handle
|
jaroslav@1692
|
835 |
* @throws NoSuchMethodException if the constructor does not exist
|
jaroslav@1692
|
836 |
* @throws IllegalAccessException if access checking fails
|
jaroslav@1692
|
837 |
* or if the method's variable arity modifier bit
|
jaroslav@1692
|
838 |
* is set and {@code asVarargsCollector} fails
|
jaroslav@1692
|
839 |
* @exception SecurityException if a security manager is present and it
|
jaroslav@1692
|
840 |
* <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
|
jaroslav@1692
|
841 |
* @throws NullPointerException if any argument is null
|
jaroslav@1692
|
842 |
*/
|
jaroslav@1692
|
843 |
public MethodHandle findConstructor(Class<?> refc, MethodType type) throws NoSuchMethodException, IllegalAccessException {
|
jaroslav@1692
|
844 |
throw new IllegalStateException();
|
jaroslav@1692
|
845 |
}
|
jaroslav@1692
|
846 |
|
jaroslav@1692
|
847 |
/**
|
jaroslav@1692
|
848 |
* Produces an early-bound method handle for a virtual method.
|
jaroslav@1692
|
849 |
* It will bypass checks for overriding methods on the receiver,
|
jaroslav@1692
|
850 |
* <a href="MethodHandles.Lookup.html#equiv">as if called</a> from an {@code invokespecial}
|
jaroslav@1692
|
851 |
* instruction from within the explicitly specified {@code specialCaller}.
|
jaroslav@1692
|
852 |
* The type of the method handle will be that of the method,
|
jaroslav@1692
|
853 |
* with a suitably restricted receiver type prepended.
|
jaroslav@1692
|
854 |
* (The receiver type will be {@code specialCaller} or a subtype.)
|
jaroslav@1692
|
855 |
* The method and all its argument types must be accessible
|
jaroslav@1692
|
856 |
* to the lookup object.
|
jaroslav@1692
|
857 |
* <p>
|
jaroslav@1692
|
858 |
* Before method resolution,
|
jaroslav@1692
|
859 |
* if the explicitly specified caller class is not identical with the
|
jaroslav@1692
|
860 |
* lookup class, or if this lookup object does not have
|
jaroslav@1692
|
861 |
* <a href="MethodHandles.Lookup.html#privacc">private access</a>
|
jaroslav@1692
|
862 |
* privileges, the access fails.
|
jaroslav@1692
|
863 |
* <p>
|
jaroslav@1692
|
864 |
* The returned method handle will have
|
jaroslav@1692
|
865 |
* {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if
|
jaroslav@1692
|
866 |
* the method's variable arity modifier bit ({@code 0x0080}) is set.
|
jaroslav@1692
|
867 |
* <p style="font-size:smaller;">
|
jaroslav@1692
|
868 |
* <em>(Note: JVM internal methods named {@code "<init>"} are not visible to this API,
|
jaroslav@1692
|
869 |
* even though the {@code invokespecial} instruction can refer to them
|
jaroslav@1692
|
870 |
* in special circumstances. Use {@link #findConstructor findConstructor}
|
jaroslav@1692
|
871 |
* to access instance initialization methods in a safe manner.)</em>
|
jaroslav@1692
|
872 |
* <p><b>Example:</b>
|
jaroslav@1692
|
873 |
* <blockquote><pre>{@code
|
jaroslav@1692
|
874 |
import static java.lang.invoke.MethodHandles.*;
|
jaroslav@1692
|
875 |
import static java.lang.invoke.MethodType.*;
|
jaroslav@1692
|
876 |
...
|
jaroslav@1692
|
877 |
static class Listie extends ArrayList {
|
jaroslav@1692
|
878 |
public String toString() { return "[wee Listie]"; }
|
jaroslav@1692
|
879 |
static Lookup lookup() { return MethodHandles.lookup(); }
|
jaroslav@1692
|
880 |
}
|
jaroslav@1692
|
881 |
...
|
jaroslav@1692
|
882 |
// no access to constructor via invokeSpecial:
|
jaroslav@1692
|
883 |
MethodHandle MH_newListie = Listie.lookup()
|
jaroslav@1692
|
884 |
.findConstructor(Listie.class, methodType(void.class));
|
jaroslav@1692
|
885 |
Listie l = (Listie) MH_newListie.invokeExact();
|
jaroslav@1692
|
886 |
try { assertEquals("impossible", Listie.lookup().findSpecial(
|
jaroslav@1692
|
887 |
Listie.class, "<init>", methodType(void.class), Listie.class));
|
jaroslav@1692
|
888 |
} catch (NoSuchMethodException ex) { } // OK
|
jaroslav@1692
|
889 |
// access to super and self methods via invokeSpecial:
|
jaroslav@1692
|
890 |
MethodHandle MH_super = Listie.lookup().findSpecial(
|
jaroslav@1692
|
891 |
ArrayList.class, "toString" , methodType(String.class), Listie.class);
|
jaroslav@1692
|
892 |
MethodHandle MH_this = Listie.lookup().findSpecial(
|
jaroslav@1692
|
893 |
Listie.class, "toString" , methodType(String.class), Listie.class);
|
jaroslav@1692
|
894 |
MethodHandle MH_duper = Listie.lookup().findSpecial(
|
jaroslav@1692
|
895 |
Object.class, "toString" , methodType(String.class), Listie.class);
|
jaroslav@1692
|
896 |
assertEquals("[]", (String) MH_super.invokeExact(l));
|
jaroslav@1692
|
897 |
assertEquals(""+l, (String) MH_this.invokeExact(l));
|
jaroslav@1692
|
898 |
assertEquals("[]", (String) MH_duper.invokeExact(l)); // ArrayList method
|
jaroslav@1692
|
899 |
try { assertEquals("inaccessible", Listie.lookup().findSpecial(
|
jaroslav@1692
|
900 |
String.class, "toString", methodType(String.class), Listie.class));
|
jaroslav@1692
|
901 |
} catch (IllegalAccessException ex) { } // OK
|
jaroslav@1692
|
902 |
Listie subl = new Listie() { public String toString() { return "[subclass]"; } };
|
jaroslav@1692
|
903 |
assertEquals(""+l, (String) MH_this.invokeExact(subl)); // Listie method
|
jaroslav@1692
|
904 |
* }</pre></blockquote>
|
jaroslav@1692
|
905 |
*
|
jaroslav@1692
|
906 |
* @param refc the class or interface from which the method is accessed
|
jaroslav@1692
|
907 |
* @param name the name of the method (which must not be "<init>")
|
jaroslav@1692
|
908 |
* @param type the type of the method, with the receiver argument omitted
|
jaroslav@1692
|
909 |
* @param specialCaller the proposed calling class to perform the {@code invokespecial}
|
jaroslav@1692
|
910 |
* @return the desired method handle
|
jaroslav@1692
|
911 |
* @throws NoSuchMethodException if the method does not exist
|
jaroslav@1692
|
912 |
* @throws IllegalAccessException if access checking fails
|
jaroslav@1692
|
913 |
* or if the method's variable arity modifier bit
|
jaroslav@1692
|
914 |
* is set and {@code asVarargsCollector} fails
|
jaroslav@1692
|
915 |
* @exception SecurityException if a security manager is present and it
|
jaroslav@1692
|
916 |
* <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
|
jaroslav@1692
|
917 |
* @throws NullPointerException if any argument is null
|
jaroslav@1692
|
918 |
*/
|
jaroslav@1692
|
919 |
public MethodHandle findSpecial(Class<?> refc, String name, MethodType type,
|
jaroslav@1692
|
920 |
Class<?> specialCaller) throws NoSuchMethodException, IllegalAccessException {
|
jaroslav@1692
|
921 |
throw new IllegalStateException();
|
jaroslav@1692
|
922 |
}
|
jaroslav@1692
|
923 |
|
jaroslav@1692
|
924 |
/**
|
jaroslav@1692
|
925 |
* Produces a method handle giving read access to a non-static field.
|
jaroslav@1692
|
926 |
* The type of the method handle will have a return type of the field's
|
jaroslav@1692
|
927 |
* value type.
|
jaroslav@1692
|
928 |
* The method handle's single argument will be the instance containing
|
jaroslav@1692
|
929 |
* the field.
|
jaroslav@1692
|
930 |
* Access checking is performed immediately on behalf of the lookup class.
|
jaroslav@1692
|
931 |
* @param refc the class or interface from which the method is accessed
|
jaroslav@1692
|
932 |
* @param name the field's name
|
jaroslav@1692
|
933 |
* @param type the field's type
|
jaroslav@1692
|
934 |
* @return a method handle which can load values from the field
|
jaroslav@1692
|
935 |
* @throws NoSuchFieldException if the field does not exist
|
jaroslav@1692
|
936 |
* @throws IllegalAccessException if access checking fails, or if the field is {@code static}
|
jaroslav@1692
|
937 |
* @exception SecurityException if a security manager is present and it
|
jaroslav@1692
|
938 |
* <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
|
jaroslav@1692
|
939 |
* @throws NullPointerException if any argument is null
|
jaroslav@1692
|
940 |
*/
|
jaroslav@1692
|
941 |
public MethodHandle findGetter(Class<?> refc, String name, Class<?> type) throws IllegalAccessException {
|
jaroslav@1692
|
942 |
throw new IllegalStateException();
|
jaroslav@1692
|
943 |
}
|
jaroslav@1692
|
944 |
|
jaroslav@1692
|
945 |
/**
|
jaroslav@1692
|
946 |
* Produces a method handle giving write access to a non-static field.
|
jaroslav@1692
|
947 |
* The type of the method handle will have a void return type.
|
jaroslav@1692
|
948 |
* The method handle will take two arguments, the instance containing
|
jaroslav@1692
|
949 |
* the field, and the value to be stored.
|
jaroslav@1692
|
950 |
* The second argument will be of the field's value type.
|
jaroslav@1692
|
951 |
* Access checking is performed immediately on behalf of the lookup class.
|
jaroslav@1692
|
952 |
* @param refc the class or interface from which the method is accessed
|
jaroslav@1692
|
953 |
* @param name the field's name
|
jaroslav@1692
|
954 |
* @param type the field's type
|
jaroslav@1692
|
955 |
* @return a method handle which can store values into the field
|
jaroslav@1692
|
956 |
* @throws NoSuchFieldException if the field does not exist
|
jaroslav@1692
|
957 |
* @throws IllegalAccessException if access checking fails, or if the field is {@code static}
|
jaroslav@1692
|
958 |
* @exception SecurityException if a security manager is present and it
|
jaroslav@1692
|
959 |
* <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
|
jaroslav@1692
|
960 |
* @throws NullPointerException if any argument is null
|
jaroslav@1692
|
961 |
*/
|
jaroslav@1692
|
962 |
public MethodHandle findSetter(Class<?> refc, String name, Class<?> type) throws IllegalAccessException {
|
jaroslav@1692
|
963 |
throw new IllegalStateException();
|
jaroslav@1692
|
964 |
}
|
jaroslav@1692
|
965 |
|
jaroslav@1692
|
966 |
/**
|
jaroslav@1692
|
967 |
* Produces a method handle giving read access to a static field.
|
jaroslav@1692
|
968 |
* The type of the method handle will have a return type of the field's
|
jaroslav@1692
|
969 |
* value type.
|
jaroslav@1692
|
970 |
* The method handle will take no arguments.
|
jaroslav@1692
|
971 |
* Access checking is performed immediately on behalf of the lookup class.
|
jaroslav@1692
|
972 |
* <p>
|
jaroslav@1692
|
973 |
* If the returned method handle is invoked, the field's class will
|
jaroslav@1692
|
974 |
* be initialized, if it has not already been initialized.
|
jaroslav@1692
|
975 |
* @param refc the class or interface from which the method is accessed
|
jaroslav@1692
|
976 |
* @param name the field's name
|
jaroslav@1692
|
977 |
* @param type the field's type
|
jaroslav@1692
|
978 |
* @return a method handle which can load values from the field
|
jaroslav@1692
|
979 |
* @throws NoSuchFieldException if the field does not exist
|
jaroslav@1692
|
980 |
* @throws IllegalAccessException if access checking fails, or if the field is not {@code static}
|
jaroslav@1692
|
981 |
* @exception SecurityException if a security manager is present and it
|
jaroslav@1692
|
982 |
* <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
|
jaroslav@1692
|
983 |
* @throws NullPointerException if any argument is null
|
jaroslav@1692
|
984 |
*/
|
jaroslav@1692
|
985 |
public MethodHandle findStaticGetter(Class<?> refc, String name, Class<?> type) throws IllegalAccessException {
|
jaroslav@1692
|
986 |
throw new IllegalStateException();
|
jaroslav@1692
|
987 |
}
|
jaroslav@1692
|
988 |
|
jaroslav@1692
|
989 |
/**
|
jaroslav@1692
|
990 |
* Produces a method handle giving write access to a static field.
|
jaroslav@1692
|
991 |
* The type of the method handle will have a void return type.
|
jaroslav@1692
|
992 |
* The method handle will take a single
|
jaroslav@1692
|
993 |
* argument, of the field's value type, the value to be stored.
|
jaroslav@1692
|
994 |
* Access checking is performed immediately on behalf of the lookup class.
|
jaroslav@1692
|
995 |
* <p>
|
jaroslav@1692
|
996 |
* If the returned method handle is invoked, the field's class will
|
jaroslav@1692
|
997 |
* be initialized, if it has not already been initialized.
|
jaroslav@1692
|
998 |
* @param refc the class or interface from which the method is accessed
|
jaroslav@1692
|
999 |
* @param name the field's name
|
jaroslav@1692
|
1000 |
* @param type the field's type
|
jaroslav@1692
|
1001 |
* @return a method handle which can store values into the field
|
jaroslav@1692
|
1002 |
* @throws NoSuchFieldException if the field does not exist
|
jaroslav@1692
|
1003 |
* @throws IllegalAccessException if access checking fails, or if the field is not {@code static}
|
jaroslav@1692
|
1004 |
* @exception SecurityException if a security manager is present and it
|
jaroslav@1692
|
1005 |
* <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
|
jaroslav@1692
|
1006 |
* @throws NullPointerException if any argument is null
|
jaroslav@1692
|
1007 |
*/
|
jaroslav@1692
|
1008 |
public MethodHandle findStaticSetter(Class<?> refc, String name, Class<?> type) throws IllegalAccessException {
|
jaroslav@1692
|
1009 |
throw new IllegalStateException();
|
jaroslav@1692
|
1010 |
}
|
jaroslav@1692
|
1011 |
|
jaroslav@1692
|
1012 |
/**
|
jaroslav@1692
|
1013 |
* Produces an early-bound method handle for a non-static method.
|
jaroslav@1692
|
1014 |
* The receiver must have a supertype {@code defc} in which a method
|
jaroslav@1692
|
1015 |
* of the given name and type is accessible to the lookup class.
|
jaroslav@1692
|
1016 |
* The method and all its argument types must be accessible to the lookup object.
|
jaroslav@1692
|
1017 |
* The type of the method handle will be that of the method,
|
jaroslav@1692
|
1018 |
* without any insertion of an additional receiver parameter.
|
jaroslav@1692
|
1019 |
* The given receiver will be bound into the method handle,
|
jaroslav@1692
|
1020 |
* so that every call to the method handle will invoke the
|
jaroslav@1692
|
1021 |
* requested method on the given receiver.
|
jaroslav@1692
|
1022 |
* <p>
|
jaroslav@1692
|
1023 |
* The returned method handle will have
|
jaroslav@1692
|
1024 |
* {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if
|
jaroslav@1692
|
1025 |
* the method's variable arity modifier bit ({@code 0x0080}) is set
|
jaroslav@1692
|
1026 |
* <em>and</em> the trailing array argument is not the only argument.
|
jaroslav@1692
|
1027 |
* (If the trailing array argument is the only argument,
|
jaroslav@1692
|
1028 |
* the given receiver value will be bound to it.)
|
jaroslav@1692
|
1029 |
* <p>
|
jaroslav@1692
|
1030 |
* This is equivalent to the following code:
|
jaroslav@1692
|
1031 |
* <blockquote><pre>{@code
|
jaroslav@1692
|
1032 |
import static java.lang.invoke.MethodHandles.*;
|
jaroslav@1692
|
1033 |
import static java.lang.invoke.MethodType.*;
|
jaroslav@1692
|
1034 |
...
|
jaroslav@1692
|
1035 |
MethodHandle mh0 = lookup().findVirtual(defc, name, type);
|
jaroslav@1692
|
1036 |
MethodHandle mh1 = mh0.bindTo(receiver);
|
jaroslav@1692
|
1037 |
MethodType mt1 = mh1.type();
|
jaroslav@1692
|
1038 |
if (mh0.isVarargsCollector())
|
jaroslav@1692
|
1039 |
mh1 = mh1.asVarargsCollector(mt1.parameterType(mt1.parameterCount()-1));
|
jaroslav@1692
|
1040 |
return mh1;
|
jaroslav@1692
|
1041 |
* }</pre></blockquote>
|
jaroslav@1692
|
1042 |
* where {@code defc} is either {@code receiver.getClass()} or a super
|
jaroslav@1692
|
1043 |
* type of that class, in which the requested method is accessible
|
jaroslav@1692
|
1044 |
* to the lookup class.
|
jaroslav@1692
|
1045 |
* (Note that {@code bindTo} does not preserve variable arity.)
|
jaroslav@1692
|
1046 |
* @param receiver the object from which the method is accessed
|
jaroslav@1692
|
1047 |
* @param name the name of the method
|
jaroslav@1692
|
1048 |
* @param type the type of the method, with the receiver argument omitted
|
jaroslav@1692
|
1049 |
* @return the desired method handle
|
jaroslav@1692
|
1050 |
* @throws NoSuchMethodException if the method does not exist
|
jaroslav@1692
|
1051 |
* @throws IllegalAccessException if access checking fails
|
jaroslav@1692
|
1052 |
* or if the method's variable arity modifier bit
|
jaroslav@1692
|
1053 |
* is set and {@code asVarargsCollector} fails
|
jaroslav@1692
|
1054 |
* @exception SecurityException if a security manager is present and it
|
jaroslav@1692
|
1055 |
* <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
|
jaroslav@1692
|
1056 |
* @throws NullPointerException if any argument is null
|
jaroslav@1692
|
1057 |
* @see MethodHandle#bindTo
|
jaroslav@1692
|
1058 |
* @see #findVirtual
|
jaroslav@1692
|
1059 |
*/
|
jaroslav@1692
|
1060 |
public MethodHandle bind(Object receiver, String name, MethodType type) throws NoSuchMethodException, IllegalAccessException {
|
jaroslav@1692
|
1061 |
throw new IllegalStateException();
|
jaroslav@1692
|
1062 |
}
|
jaroslav@1692
|
1063 |
|
jaroslav@1692
|
1064 |
/**
|
jaroslav@1692
|
1065 |
* Makes a <a href="MethodHandleInfo.html#directmh">direct method handle</a>
|
jaroslav@1692
|
1066 |
* to <i>m</i>, if the lookup class has permission.
|
jaroslav@1692
|
1067 |
* If <i>m</i> is non-static, the receiver argument is treated as an initial argument.
|
jaroslav@1692
|
1068 |
* If <i>m</i> is virtual, overriding is respected on every call.
|
jaroslav@1692
|
1069 |
* Unlike the Core Reflection API, exceptions are <em>not</em> wrapped.
|
jaroslav@1692
|
1070 |
* The type of the method handle will be that of the method,
|
jaroslav@1692
|
1071 |
* with the receiver type prepended (but only if it is non-static).
|
jaroslav@1692
|
1072 |
* If the method's {@code accessible} flag is not set,
|
jaroslav@1692
|
1073 |
* access checking is performed immediately on behalf of the lookup class.
|
jaroslav@1692
|
1074 |
* If <i>m</i> is not public, do not share the resulting handle with untrusted parties.
|
jaroslav@1692
|
1075 |
* <p>
|
jaroslav@1692
|
1076 |
* The returned method handle will have
|
jaroslav@1692
|
1077 |
* {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if
|
jaroslav@1692
|
1078 |
* the method's variable arity modifier bit ({@code 0x0080}) is set.
|
jaroslav@1692
|
1079 |
* <p>
|
jaroslav@1692
|
1080 |
* If <i>m</i> is static, and
|
jaroslav@1692
|
1081 |
* if the returned method handle is invoked, the method's class will
|
jaroslav@1692
|
1082 |
* be initialized, if it has not already been initialized.
|
jaroslav@1692
|
1083 |
* @param m the reflected method
|
jaroslav@1692
|
1084 |
* @return a method handle which can invoke the reflected method
|
jaroslav@1692
|
1085 |
* @throws IllegalAccessException if access checking fails
|
jaroslav@1692
|
1086 |
* or if the method's variable arity modifier bit
|
jaroslav@1692
|
1087 |
* is set and {@code asVarargsCollector} fails
|
jaroslav@1692
|
1088 |
* @throws NullPointerException if the argument is null
|
jaroslav@1692
|
1089 |
*/
|
jaroslav@1692
|
1090 |
public MethodHandle unreflect(Method m) throws IllegalAccessException {
|
jaroslav@1692
|
1091 |
throw new IllegalStateException();
|
jaroslav@1692
|
1092 |
}
|
jaroslav@1692
|
1093 |
|
jaroslav@1692
|
1094 |
/**
|
jaroslav@1692
|
1095 |
* Produces a method handle for a reflected method.
|
jaroslav@1692
|
1096 |
* It will bypass checks for overriding methods on the receiver,
|
jaroslav@1692
|
1097 |
* <a href="MethodHandles.Lookup.html#equiv">as if called</a> from an {@code invokespecial}
|
jaroslav@1692
|
1098 |
* instruction from within the explicitly specified {@code specialCaller}.
|
jaroslav@1692
|
1099 |
* The type of the method handle will be that of the method,
|
jaroslav@1692
|
1100 |
* with a suitably restricted receiver type prepended.
|
jaroslav@1692
|
1101 |
* (The receiver type will be {@code specialCaller} or a subtype.)
|
jaroslav@1692
|
1102 |
* If the method's {@code accessible} flag is not set,
|
jaroslav@1692
|
1103 |
* access checking is performed immediately on behalf of the lookup class,
|
jaroslav@1692
|
1104 |
* as if {@code invokespecial} instruction were being linked.
|
jaroslav@1692
|
1105 |
* <p>
|
jaroslav@1692
|
1106 |
* Before method resolution,
|
jaroslav@1692
|
1107 |
* if the explicitly specified caller class is not identical with the
|
jaroslav@1692
|
1108 |
* lookup class, or if this lookup object does not have
|
jaroslav@1692
|
1109 |
* <a href="MethodHandles.Lookup.html#privacc">private access</a>
|
jaroslav@1692
|
1110 |
* privileges, the access fails.
|
jaroslav@1692
|
1111 |
* <p>
|
jaroslav@1692
|
1112 |
* The returned method handle will have
|
jaroslav@1692
|
1113 |
* {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if
|
jaroslav@1692
|
1114 |
* the method's variable arity modifier bit ({@code 0x0080}) is set.
|
jaroslav@1692
|
1115 |
* @param m the reflected method
|
jaroslav@1692
|
1116 |
* @param specialCaller the class nominally calling the method
|
jaroslav@1692
|
1117 |
* @return a method handle which can invoke the reflected method
|
jaroslav@1692
|
1118 |
* @throws IllegalAccessException if access checking fails
|
jaroslav@1692
|
1119 |
* or if the method's variable arity modifier bit
|
jaroslav@1692
|
1120 |
* is set and {@code asVarargsCollector} fails
|
jaroslav@1692
|
1121 |
* @throws NullPointerException if any argument is null
|
jaroslav@1692
|
1122 |
*/
|
jaroslav@1692
|
1123 |
public MethodHandle unreflectSpecial(Method m, Class<?> specialCaller) throws IllegalAccessException {
|
jaroslav@1692
|
1124 |
throw new IllegalStateException();
|
jaroslav@1692
|
1125 |
}
|
jaroslav@1692
|
1126 |
|
jaroslav@1692
|
1127 |
/**
|
jaroslav@1692
|
1128 |
* Produces a method handle for a reflected constructor.
|
jaroslav@1692
|
1129 |
* The type of the method handle will be that of the constructor,
|
jaroslav@1692
|
1130 |
* with the return type changed to the declaring class.
|
jaroslav@1692
|
1131 |
* The method handle will perform a {@code newInstance} operation,
|
jaroslav@1692
|
1132 |
* creating a new instance of the constructor's class on the
|
jaroslav@1692
|
1133 |
* arguments passed to the method handle.
|
jaroslav@1692
|
1134 |
* <p>
|
jaroslav@1692
|
1135 |
* If the constructor's {@code accessible} flag is not set,
|
jaroslav@1692
|
1136 |
* access checking is performed immediately on behalf of the lookup class.
|
jaroslav@1692
|
1137 |
* <p>
|
jaroslav@1692
|
1138 |
* The returned method handle will have
|
jaroslav@1692
|
1139 |
* {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if
|
jaroslav@1692
|
1140 |
* the constructor's variable arity modifier bit ({@code 0x0080}) is set.
|
jaroslav@1692
|
1141 |
* <p>
|
jaroslav@1692
|
1142 |
* If the returned method handle is invoked, the constructor's class will
|
jaroslav@1692
|
1143 |
* be initialized, if it has not already been initialized.
|
jaroslav@1692
|
1144 |
* @param c the reflected constructor
|
jaroslav@1692
|
1145 |
* @return a method handle which can invoke the reflected constructor
|
jaroslav@1692
|
1146 |
* @throws IllegalAccessException if access checking fails
|
jaroslav@1692
|
1147 |
* or if the method's variable arity modifier bit
|
jaroslav@1692
|
1148 |
* is set and {@code asVarargsCollector} fails
|
jaroslav@1692
|
1149 |
* @throws NullPointerException if the argument is null
|
jaroslav@1692
|
1150 |
*/
|
jaroslav@1692
|
1151 |
public MethodHandle unreflectConstructor(Constructor<?> c) throws IllegalAccessException {
|
jaroslav@1692
|
1152 |
throw new IllegalStateException();
|
jaroslav@1692
|
1153 |
}
|
jaroslav@1692
|
1154 |
|
jaroslav@1692
|
1155 |
/**
|
jaroslav@1692
|
1156 |
* Produces a method handle giving read access to a reflected field.
|
jaroslav@1692
|
1157 |
* The type of the method handle will have a return type of the field's
|
jaroslav@1692
|
1158 |
* value type.
|
jaroslav@1692
|
1159 |
* If the field is static, the method handle will take no arguments.
|
jaroslav@1692
|
1160 |
* Otherwise, its single argument will be the instance containing
|
jaroslav@1692
|
1161 |
* the field.
|
jaroslav@1692
|
1162 |
* If the field's {@code accessible} flag is not set,
|
jaroslav@1692
|
1163 |
* access checking is performed immediately on behalf of the lookup class.
|
jaroslav@1692
|
1164 |
* <p>
|
jaroslav@1692
|
1165 |
* If the field is static, and
|
jaroslav@1692
|
1166 |
* if the returned method handle is invoked, the field's class will
|
jaroslav@1692
|
1167 |
* be initialized, if it has not already been initialized.
|
jaroslav@1692
|
1168 |
* @param f the reflected field
|
jaroslav@1692
|
1169 |
* @return a method handle which can load values from the reflected field
|
jaroslav@1692
|
1170 |
* @throws IllegalAccessException if access checking fails
|
jaroslav@1692
|
1171 |
* @throws NullPointerException if the argument is null
|
jaroslav@1692
|
1172 |
*/
|
jaroslav@1692
|
1173 |
public MethodHandle unreflectGetter(Field f) throws IllegalAccessException {
|
jaroslav@1692
|
1174 |
throw new IllegalStateException();
|
jaroslav@1692
|
1175 |
}
|
jaroslav@1692
|
1176 |
|
jaroslav@1692
|
1177 |
/**
|
jaroslav@1692
|
1178 |
* Produces a method handle giving write access to a reflected field.
|
jaroslav@1692
|
1179 |
* The type of the method handle will have a void return type.
|
jaroslav@1692
|
1180 |
* If the field is static, the method handle will take a single
|
jaroslav@1692
|
1181 |
* argument, of the field's value type, the value to be stored.
|
jaroslav@1692
|
1182 |
* Otherwise, the two arguments will be the instance containing
|
jaroslav@1692
|
1183 |
* the field, and the value to be stored.
|
jaroslav@1692
|
1184 |
* If the field's {@code accessible} flag is not set,
|
jaroslav@1692
|
1185 |
* access checking is performed immediately on behalf of the lookup class.
|
jaroslav@1692
|
1186 |
* <p>
|
jaroslav@1692
|
1187 |
* If the field is static, and
|
jaroslav@1692
|
1188 |
* if the returned method handle is invoked, the field's class will
|
jaroslav@1692
|
1189 |
* be initialized, if it has not already been initialized.
|
jaroslav@1692
|
1190 |
* @param f the reflected field
|
jaroslav@1692
|
1191 |
* @return a method handle which can store values into the reflected field
|
jaroslav@1692
|
1192 |
* @throws IllegalAccessException if access checking fails
|
jaroslav@1692
|
1193 |
* @throws NullPointerException if the argument is null
|
jaroslav@1692
|
1194 |
*/
|
jaroslav@1692
|
1195 |
public MethodHandle unreflectSetter(Field f) throws IllegalAccessException {
|
jaroslav@1692
|
1196 |
throw new IllegalStateException();
|
jaroslav@1692
|
1197 |
}
|
jaroslav@1692
|
1198 |
|
jaroslav@1692
|
1199 |
/**
|
jaroslav@1692
|
1200 |
* Cracks a <a href="MethodHandleInfo.html#directmh">direct method handle</a>
|
jaroslav@1692
|
1201 |
* created by this lookup object or a similar one.
|
jaroslav@1692
|
1202 |
* Security and access checks are performed to ensure that this lookup object
|
jaroslav@1692
|
1203 |
* is capable of reproducing the target method handle.
|
jaroslav@1692
|
1204 |
* This means that the cracking may fail if target is a direct method handle
|
jaroslav@1692
|
1205 |
* but was created by an unrelated lookup object.
|
jaroslav@1692
|
1206 |
* This can happen if the method handle is <a href="MethodHandles.Lookup.html#callsens">caller sensitive</a>
|
jaroslav@1692
|
1207 |
* and was created by a lookup object for a different class.
|
jaroslav@1692
|
1208 |
* @param target a direct method handle to crack into symbolic reference components
|
jaroslav@1692
|
1209 |
* @return a symbolic reference which can be used to reconstruct this method handle from this lookup object
|
jaroslav@1692
|
1210 |
* @exception SecurityException if a security manager is present and it
|
jaroslav@1692
|
1211 |
* <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
|
jaroslav@1692
|
1212 |
* @throws IllegalArgumentException if the target is not a direct method handle or if access checking fails
|
jaroslav@1692
|
1213 |
* @exception NullPointerException if the target is {@code null}
|
jaroslav@1692
|
1214 |
* @see MethodHandleInfo
|
jaroslav@1692
|
1215 |
* @since 1.8
|
jaroslav@1692
|
1216 |
*/
|
jaroslav@1692
|
1217 |
// public MethodHandleInfo revealDirect(MethodHandle target) {
|
jaroslav@1692
|
1218 |
// throw new IllegalStateException();
|
jaroslav@1692
|
1219 |
// }
|
jaroslav@1692
|
1220 |
}
|
jaroslav@1692
|
1221 |
|
jaroslav@1692
|
1222 |
}
|