/*
* 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
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*/
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();
}
}