1 /* 2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.security; 27 28 /** 29 * A GuardedObject is an object that is used to protect access to 30 * another object. 31 * 32 * <p>A GuardedObject encapsulates a target object and a Guard object, 33 * such that access to the target object is possible 34 * only if the Guard object allows it. 35 * Once an object is encapsulated by a GuardedObject, 36 * access to that object is controlled by the {@code getObject} 37 * method, which invokes the 38 * {@code checkGuard} method on the Guard object that is 39 * guarding access. If access is not allowed, 40 * an exception is thrown. 41 * 42 * @see Guard 43 * @see Permission 44 * 45 * @author Roland Schemers 46 * @author Li Gong 47 */ 48 49 public class GuardedObject implements java.io.Serializable { 50 51 private static final long serialVersionUID = -5240450096227834308L; 52 53 private Object object; // the object we are guarding 54 private Guard guard; // the guard 55 56 /** 57 * Constructs a GuardedObject using the specified object and guard. 58 * If the Guard object is null, then no restrictions will 59 * be placed on who can access the object. 60 * 61 * @param object the object to be guarded. 62 * 63 * @param guard the Guard object that guards access to the object. 64 */ 65 GuardedObject(Object object, Guard guard)66 public GuardedObject(Object object, Guard guard) 67 { 68 this.guard = guard; 69 this.object = object; 70 } 71 72 /** 73 * Retrieves the guarded object, or throws an exception if access 74 * to the guarded object is denied by the guard. 75 * 76 * @return the guarded object. 77 * 78 * @exception SecurityException if access to the guarded object is 79 * denied. 80 */ getObject()81 public Object getObject() 82 throws SecurityException 83 { 84 if (guard != null) 85 guard.checkGuard(object); 86 87 return object; 88 } 89 90 /** 91 * Writes this object out to a stream (i.e., serializes it). 92 * We check the guard if there is one. 93 */ writeObject(java.io.ObjectOutputStream oos)94 private void writeObject(java.io.ObjectOutputStream oos) 95 throws java.io.IOException 96 { 97 if (guard != null) 98 guard.checkGuard(object); 99 100 oos.defaultWriteObject(); 101 } 102 } 103