/*

 * Copyright 1996-2009 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.beans;

import com.sun.beans.finder.ClassFinder;

import java.awt.GraphicsEnvironment;

import java.beans.beancontext.BeanContext;

import java.io.IOException;

import java.io.InputStream;

import java.io.ObjectInputStream;

import java.io.ObjectStreamClass;

import java.io.StreamCorruptedException;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.Iterator;

import java.util.ServiceLoader;

import sun.awt.AppContext;

import sun.beans.AppletProxy;

/**

 * This class provides some general purpose beans control methods.

 */

public class Beans {

    private static final Object DESIGN_TIME = new Object();

    private static final Object GUI_AVAILABLE = new Object();

    /**

     * <p>

     * Instantiate a JavaBean.

     * </p>

     *

     * @param     cls         the class-loader from which we should create

     *                        the bean.  If this is null, then the system

     *                        class-loader is used.

     * @param     beanName    the name of the bean within the class-loader.

     *                        For example "sun.beanbox.foobah"

     *

     * @exception ClassNotFoundException if the class of a serialized

     *              object could not be found.

     * @exception IOException if an I/O error occurs.

     */

    public static Object instantiate(ClassLoader cls, String beanName) throws IOException, ClassNotFoundException {

        return Beans.instantiate(cls, beanName, null, null);

    }

    /**

     * <p>

     * Instantiate a JavaBean.

     * </p>

     *

     * @param     cls         the class-loader from which we should create

     *                        the bean.  If this is null, then the system

     *                        class-loader is used.

     * @param     beanName    the name of the bean within the class-loader.

     *                        For example "sun.beanbox.foobah"

     * @param     beanContext The BeanContext in which to nest the new bean

     *

     * @exception ClassNotFoundException if the class of a serialized

     *              object could not be found.

     * @exception IOException if an I/O error occurs.

     */

    public static Object instantiate(ClassLoader cls, String beanName, BeanContext beanContext) throws IOException, ClassNotFoundException {

        return Beans.instantiate(cls, beanName, beanContext, null);

    }

    /**

     * Instantiate a bean.

     * <p>

     * The bean is created based on a name relative to a class-loader.

     * This name should be a dot-separated name such as "a.b.c".

     * <p>

     * In Beans 1.0 the given name can indicate either a serialized object

     * or a class.  Other mechanisms may be added in the future.  In

     * beans 1.0 we first try to treat the beanName as a serialized object

     * name then as a class name.

     * <p>

     * When using the beanName as a serialized object name we convert the

     * given beanName to a resource pathname and add a trailing ".ser" suffix.

     * We then try to load a serialized object from that resource.

     * <p>

     * For example, given a beanName of "x.y", Beans.instantiate would first

     * try to read a serialized object from the resource "x/y.ser" and if

     * that failed it would try to load the class "x.y" and create an

     * instance of that class.

     * <p>

     * If the bean is a subtype of java.applet.Applet, then it is given

     * some special initialization.  First, it is supplied with a default

     * AppletStub and AppletContext.  Second, if it was instantiated from

     * a classname the applet's "init" method is called.  (If the bean was

     * deserialized this step is skipped.)

     * <p>

     * Note that for beans which are applets, it is the caller's responsiblity

     * to call "start" on the applet.  For correct behaviour, this should be done

     * after the applet has been added into a visible AWT container.

     * <p>

     * Note that applets created via beans.instantiate run in a slightly

     * different environment than applets running inside browsers.  In

     * particular, bean applets have no access to "parameters", so they may

     * wish to provide property get/set methods to set parameter values.  We

     * advise bean-applet developers to test their bean-applets against both

     * the JDK appletviewer (for a reference browser environment) and the

     * BDK BeanBox (for a reference bean container).

     *

     * @param     cls         the class-loader from which we should create

     *                        the bean.  If this is null, then the system

     *                        class-loader is used.

     * @param     beanName    the name of the bean within the class-loader.

     *                        For example "sun.beanbox.foobah"

     * @param     beanContext The BeanContext in which to nest the new bean

     * @param     initializer The AppletInitializer for the new bean

     *

     * @exception ClassNotFoundException if the class of a serialized

     *              object could not be found.

     * @exception IOException if an I/O error occurs.

     */

    public static Object instantiate(ClassLoader cls, String beanName, BeanContext beanContext, AppletInitializer initializer)

                        throws IOException, ClassNotFoundException {

        InputStream ins;

        ObjectInputStream oins = null;

        Object result = null;

        boolean serialized = false;

        IOException serex = null;

        // If the given classloader is null, we check if an

        // system classloader is available and (if so)

        // use that instead.

        // Note that calls on the system class loader will

        // look in the bootstrap class loader first.

        if (cls == null) {

            try {

                cls = ClassLoader.getSystemClassLoader();

            } catch (SecurityException ex) {

                // We're not allowed to access the system class loader.

                // Drop through.

            }

        }

        // Try to find a serialized object with this name

        final String serName = beanName.replace('.','/').concat(".ser");

        final ClassLoader loader = cls;

        ins = (InputStream)AccessController.doPrivileged

            (new PrivilegedAction() {

                public Object run() {

                    if (loader == null)

                        return ClassLoader.getSystemResourceAsStream(serName);

                    else

                        return loader.getResourceAsStream(serName);

                }

        });

        if (ins != null) {

            try {

                if (cls == null) {

                    oins = new ObjectInputStream(ins);

                } else {

                    oins = new ObjectInputStreamWithLoader(ins, cls);

                }

                result = oins.readObject();

                serialized = true;

                oins.close();

            } catch (IOException ex) {

                ins.close();

                // Drop through and try opening the class.  But remember

                // the exception in case we can't find the class either.

                serex = ex;

            } catch (ClassNotFoundException ex) {

                ins.close();

                throw ex;

            }

        }

        if (result == null) {

            // No serialized object, try just instantiating the class

            Class cl;

            try {

                cl = ClassFinder.findClass(beanName, cls);

            } catch (ClassNotFoundException ex) {

                // There is no appropriate class.  If we earlier tried to

                // deserialize an object and got an IO exception, throw that,

                // otherwise rethrow the ClassNotFoundException.

                if (serex != null) {

                    throw serex;

                }

                throw ex;

            }

            /*

             * Try to instantiate the class.

             */

                try {

                result = cl.newInstance();

            } catch (Exception ex) {

                // We have to remap the exception to one in our signature.

                // But we pass extra information in the detail message.

                throw new ClassNotFoundException("" + cl + " : " + ex, ex);

            }

        }

        if (result != null) {

            // Ok, if the result is an applet initialize it.

            Iterator<AppletProxy> it = ServiceLoader.load(AppletProxy.class).iterator();

            AppletProxy ap = it.hasNext() ? it.next() : null;

            if (ap != null || !ap.initialize(

                result, initializer, serialized, beanName, beanContext, cls

            )) {

                if (beanContext != null) beanContext.add(result);

            }

        }

        return result;

    }

    /**

     * From a given bean, obtain an object representing a specified

     * type view of that source object.

     * <p>

     * The result may be the same object or a different object.  If

     * the requested target view isn't available then the given

     * bean is returned.

     * <p>

     * This method is provided in Beans 1.0 as a hook to allow the

     * addition of more flexible bean behaviour in the future.

     *

     * @param bean        Object from which we want to obtain a view.

     * @param targetType  The type of view we'd like to get.

     *

     */

    public static Object getInstanceOf(Object bean, Class<?> targetType) {

        return bean;

    }

    /**

     * Check if a bean can be viewed as a given target type.

     * The result will be true if the Beans.getInstanceof method

     * can be used on the given bean to obtain an object that

     * represents the specified targetType type view.

     *

     * @param bean  Bean from which we want to obtain a view.

     * @param targetType  The type of view we'd like to get.

     * @return "true" if the given bean supports the given targetType.

     *

     */

    public static boolean isInstanceOf(Object bean, Class<?> targetType) {

        return Introspector.isSubclass(bean.getClass(), targetType);

    }

    /**

     * Test if we are in design-mode.

     *

     * @return  True if we are running in an application construction

     *          environment.

     *

     * @see DesignMode

     */

    public static boolean isDesignTime() {

        Object value = AppContext.getAppContext().get(DESIGN_TIME);

        return (value instanceof Boolean) && (Boolean) value;

    }

    /**

     * Determines whether beans can assume a GUI is available.

     *

     * @return  True if we are running in an environment where beans

     *     can assume that an interactive GUI is available, so they

     *     can pop up dialog boxes, etc.  This will normally return

     *     true in a windowing environment, and will normally return

     *     false in a server environment or if an application is

     *     running as part of a batch job.

     *

     * @see Visibility

     *

     */

    public static boolean isGuiAvailable() {

        Object value = AppContext.getAppContext().get(GUI_AVAILABLE);

        return (value instanceof Boolean) ? (Boolean) value : !GraphicsEnvironment.isHeadless();

    }

    /**

     * Used to indicate whether of not we are running in an application

     * builder environment.

     *

     * <p>Note that this method is security checked

     * and is not available to (for example) untrusted applets.

     * More specifically, if there is a security manager,

     * its <code>checkPropertiesAccess</code>

     * method is called. This could result in a SecurityException.

     *

     * @param isDesignTime  True if we're in an application builder tool.

     * @exception  SecurityException  if a security manager exists and its

     *             <code>checkPropertiesAccess</code> method doesn't allow setting

     *              of system properties.

     * @see SecurityManager#checkPropertiesAccess

     */

    public static void setDesignTime(boolean isDesignTime)

                        throws SecurityException {

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPropertiesAccess();

        }

        AppContext.getAppContext().put(DESIGN_TIME, Boolean.valueOf(isDesignTime));

    }

    /**

     * Used to indicate whether of not we are running in an environment

     * where GUI interaction is available.

     *

     * <p>Note that this method is security checked

     * and is not available to (for example) untrusted applets.

     * More specifically, if there is a security manager,

     * its <code>checkPropertiesAccess</code>

     * method is called. This could result in a SecurityException.

     *

     * @param isGuiAvailable  True if GUI interaction is available.

     * @exception  SecurityException  if a security manager exists and its

     *             <code>checkPropertiesAccess</code> method doesn't allow setting

     *              of system properties.

     * @see SecurityManager#checkPropertiesAccess

     */

    public static void setGuiAvailable(boolean isGuiAvailable)

                        throws SecurityException {

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPropertiesAccess();

        }

        AppContext.getAppContext().put(GUI_AVAILABLE, Boolean.valueOf(isGuiAvailable));

    }

}

/**

 * This subclass of ObjectInputStream delegates loading of classes to

 * an existing ClassLoader.

 */

class ObjectInputStreamWithLoader extends ObjectInputStream

{

    private ClassLoader loader;

    /**

     * Loader must be non-null;

     */

    public ObjectInputStreamWithLoader(InputStream in, ClassLoader loader)

            throws IOException, StreamCorruptedException {

        super(in);

        if (loader == null) {

            throw new IllegalArgumentException("Illegal null argument to ObjectInputStreamWithLoader");

        }

        this.loader = loader;

    }

    /**

     * Use the given ClassLoader rather than using the system class

     */

    protected Class resolveClass(ObjectStreamClass classDesc)

        throws IOException, ClassNotFoundException {

        String cname = classDesc.getName();

        return ClassFinder.resolveClass(cname, this.loader);

    }

}