definingclassloader.java

這是一個javascript 的 interpreter是了解 web browser的好材料

/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Rhino code, released
 * May 6, 1999.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1997-1999
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Norris Boyd
 *   Roger Lawrence
 *   Patrick Beard
 *   Igor Bukanov
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License Version 2 or later (the "GPL"), in which
 * case the provisions of the GPL are applicable instead of those above. If
 * you wish to allow use of your version of this file only under the terms of
 * the GPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replacing
 * them with the notice and other provisions required by the GPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the GPL.
 *
 * ***** END LICENSE BLOCK ***** */

package org.mozilla.javascript;

/**
 * Load generated classes.
 *
 * @author Norris Boyd
 */
public class DefiningClassLoader extends ClassLoader
    implements GeneratedClassLoader
{
    public DefiningClassLoader() {
        this.parentLoader = getClass().getClassLoader();
    }

    public DefiningClassLoader(ClassLoader parentLoader) {
        this.parentLoader = parentLoader;
    }

    public Class defineClass(String name, byte[] data) {
        // Use our own protection domain for the generated classes.
        // TODO: we might want to use a separate protection domain for classes
        // compiled from scripts, based on where the script was loaded from.
        return super.defineClass(name, data, 0, data.length, 
                SecurityUtilities.getProtectionDomain(getClass()));
    }

    public void linkClass(Class cl) {
        resolveClass(cl);
    }

    public Class loadClass(String name, boolean resolve)
        throws ClassNotFoundException
    {
        Class cl = findLoadedClass(name);
        if (cl == null) {
            if (parentLoader != null) {
                cl = parentLoader.loadClass(name);
            } else {
                cl = findSystemClass(name);
            }
        }
        if (resolve) {
            resolveClass(cl);
        }
        return cl;
    }

    private final ClassLoader parentLoader;
}