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/* * Copyright (c) 1997, 2004, Oracle and/or its affiliates. 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.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.security; /** * A GuardedObject is an object that is used to protect access to * another object. * * <p>A GuardedObject encapsulates a target object and a Guard object, * such that access to the target object is possible * only if the Guard object allows it. * Once an object is encapsulated by a GuardedObject, * access to that object is controlled by the <code>getObject</code> * method, which invokes the * <code>checkGuard</code> method on the Guard object that is * guarding access. If access is not allowed, * an exception is thrown. * * @see Guard * @see Permission * * @author Roland Schemers * @author Li Gong */ public class GuardedObject implements java.io.Serializable {     private static final long serialVersionUID = -5240450096227834308L;     private Object object; // the object we are guarding    private Guard guard;   // the guard     /**     * Constructs a GuardedObject using the specified object and guard.     * If the Guard object is null, then no restrictions will     * be placed on who can access the object.     *     * @param object the object to be guarded.     *     * @param guard the Guard object that guards access to the object.     */     public GuardedObject(Object object, Guard guard)    {        this.guard = guard;        this.object = object;    }     /**     * Retrieves the guarded object, or throws an exception if access     * to the guarded object is denied by the guard.     *     * @return the guarded object.     *     * @exception SecurityException if access to the guarded object is     * denied.     */    public Object getObject()        throws SecurityException    {        if (guard != null)            guard.checkGuard(object);         return object;    }     /**     * Writes this object out to a stream (i.e., serializes it).     * We check the guard if there is one.     */    private void writeObject(java.io.ObjectOutputStream oos)        throws java.io.IOException    {        if (guard != null)            guard.checkGuard(object);         oos.defaultWriteObject();    }}