jaroslav@601: /*
jaroslav@601:  * Copyright (c) 1999, 2006, Oracle and/or its affiliates. All rights reserved.
jaroslav@601:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@601:  *
jaroslav@601:  * This code is free software; you can redistribute it and/or modify it
jaroslav@601:  * under the terms of the GNU General Public License version 2 only, as
jaroslav@601:  * published by the Free Software Foundation.  Oracle designates this
jaroslav@601:  * particular file as subject to the "Classpath" exception as provided
jaroslav@601:  * by Oracle in the LICENSE file that accompanied this code.
jaroslav@601:  *
jaroslav@601:  * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@601:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@601:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jaroslav@601:  * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@601:  * accompanied this code).
jaroslav@601:  *
jaroslav@601:  * You should have received a copy of the GNU General Public License version
jaroslav@601:  * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@601:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@601:  *
jaroslav@601:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@601:  * or visit www.oracle.com if you need additional information or have any
jaroslav@601:  * questions.
jaroslav@601:  */
jaroslav@601: 
jaroslav@601: package java.lang.reflect;
jaroslav@601: 
jaroslav@601: /**
jaroslav@601:  * {@code InvocationHandler} is the interface implemented by
jaroslav@601:  * the <i>invocation handler</i> of a proxy instance.
jaroslav@601:  *
jaroslav@601:  * <p>Each proxy instance has an associated invocation handler.
jaroslav@601:  * When a method is invoked on a proxy instance, the method
jaroslav@601:  * invocation is encoded and dispatched to the {@code invoke}
jaroslav@601:  * method of its invocation handler.
jaroslav@601:  *
jaroslav@601:  * @author      Peter Jones
jaroslav@601:  * @see         Proxy
jaroslav@601:  * @since       1.3
jaroslav@601:  */
jaroslav@601: public interface InvocationHandler {
jaroslav@601: 
jaroslav@601:     /**
jaroslav@601:      * Processes a method invocation on a proxy instance and returns
jaroslav@601:      * the result.  This method will be invoked on an invocation handler
jaroslav@601:      * when a method is invoked on a proxy instance that it is
jaroslav@601:      * associated with.
jaroslav@601:      *
jaroslav@601:      * @param   proxy the proxy instance that the method was invoked on
jaroslav@601:      *
jaroslav@601:      * @param   method the {@code Method} instance corresponding to
jaroslav@601:      * the interface method invoked on the proxy instance.  The declaring
jaroslav@601:      * class of the {@code Method} object will be the interface that
jaroslav@601:      * the method was declared in, which may be a superinterface of the
jaroslav@601:      * proxy interface that the proxy class inherits the method through.
jaroslav@601:      *
jaroslav@601:      * @param   args an array of objects containing the values of the
jaroslav@601:      * arguments passed in the method invocation on the proxy instance,
jaroslav@601:      * or {@code null} if interface method takes no arguments.
jaroslav@601:      * Arguments of primitive types are wrapped in instances of the
jaroslav@601:      * appropriate primitive wrapper class, such as
jaroslav@601:      * {@code java.lang.Integer} or {@code java.lang.Boolean}.
jaroslav@601:      *
jaroslav@601:      * @return  the value to return from the method invocation on the
jaroslav@601:      * proxy instance.  If the declared return type of the interface
jaroslav@601:      * method is a primitive type, then the value returned by
jaroslav@601:      * this method must be an instance of the corresponding primitive
jaroslav@601:      * wrapper class; otherwise, it must be a type assignable to the
jaroslav@601:      * declared return type.  If the value returned by this method is
jaroslav@601:      * {@code null} and the interface method's return type is
jaroslav@601:      * primitive, then a {@code NullPointerException} will be
jaroslav@601:      * thrown by the method invocation on the proxy instance.  If the
jaroslav@601:      * value returned by this method is otherwise not compatible with
jaroslav@601:      * the interface method's declared return type as described above,
jaroslav@601:      * a {@code ClassCastException} will be thrown by the method
jaroslav@601:      * invocation on the proxy instance.
jaroslav@601:      *
jaroslav@601:      * @throws  Throwable the exception to throw from the method
jaroslav@601:      * invocation on the proxy instance.  The exception's type must be
jaroslav@601:      * assignable either to any of the exception types declared in the
jaroslav@601:      * {@code throws} clause of the interface method or to the
jaroslav@601:      * unchecked exception types {@code java.lang.RuntimeException}
jaroslav@601:      * or {@code java.lang.Error}.  If a checked exception is
jaroslav@601:      * thrown by this method that is not assignable to any of the
jaroslav@601:      * exception types declared in the {@code throws} clause of
jaroslav@601:      * the interface method, then an
jaroslav@601:      * {@link UndeclaredThrowableException} containing the
jaroslav@601:      * exception that was thrown by this method will be thrown by the
jaroslav@601:      * method invocation on the proxy instance.
jaroslav@601:      *
jaroslav@601:      * @see     UndeclaredThrowableException
jaroslav@601:      */
jaroslav@601:     public Object invoke(Object proxy, Method method, Object[] args)
jaroslav@601:         throws Throwable;
jaroslav@601: }