1: /* GuardedObject.java -- An object protected by a Guard 2: Copyright (C) 1998, 2002, 2004, 2005 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package java.security; 40: 41: import java.io.IOException; 42: import java.io.ObjectOutputStream; 43: import java.io.Serializable; 44: 45: /** 46: * This class is an object that is guarded by a <code>Guard</code> object. 47: * The object that is being guarded is retrieved by a call to the only 48: * method in this class - <code>getObject</code>. That method returns the 49: * guarded <code>Object</code> after first checking with the 50: * <code>Guard</code>. If the <code>Guard</code> disallows access, an 51: * exception will be thrown. 52: * 53: * @author Aaron M. Renn (arenn@urbanophile.com) 54: * @since 1.1 55: * @status updated to 1.4 56: */ 57: public class GuardedObject implements Serializable 58: { 59: /** 60: * Compatible with JDK 1.1+. 61: */ 62: private static final long serialVersionUID = -5240450096227834308L; 63: 64: /** 65: * This is the Guard that is protecting the object. 66: * 67: * @serial the guard 68: */ 69: private final Guard guard; 70: 71: /** 72: * This is the object that is being guarded. 73: * 74: * @serial the protected object 75: */ 76: private final Object object; 77: 78: /** 79: * This method initializes a new instance of <code>GuardedObject</code> 80: * that protects the specified <code>Object</code> using the specified 81: * <code>Guard</code>. A null guard means there are no restrictions on 82: * accessing the object. 83: * 84: * @param object the <code>Object</code> to guard 85: * @param guard the <code>Guard</code> that is protecting the object 86: */ 87: public GuardedObject(Object object, Guard guard) 88: { 89: this.object = object; 90: this.guard = guard; 91: } 92: 93: /** 94: * This method first call the <code>checkGuard</code> method on the 95: * <code>Guard</code> object protecting the guarded object. If the 96: * <code>Guard</code> disallows access, an exception is thrown, otherwise 97: * the <code>Object</code> is returned. 98: * 99: * @return The object being guarded 100: * @throws SecurityException if access is denied 101: */ 102: public Object getObject() 103: { 104: if (guard != null) 105: guard.checkGuard(object); 106: return object; 107: } 108: 109: /** 110: * Ensures that serialization is legal, by checking the guard. 111: * 112: * @param s the stream to write to 113: * @throws IOException if the underlying stream fails 114: */ 115: private void writeObject(ObjectOutputStream s) throws IOException 116: { 117: if (guard != null) 118: guard.checkGuard(object); 119: s.defaultWriteObject(); 120: } 121: } // class GuardedObject