104 lines
3.3 KiB
Java
104 lines
3.3 KiB
Java
/*
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* Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.security;
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/**
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* A GuardedObject is an object that is used to protect access to
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* another object.
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*
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* <p>A GuardedObject encapsulates a target object and a Guard object,
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* such that access to the target object is possible
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* only if the Guard object allows it.
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* Once an object is encapsulated by a GuardedObject,
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* access to that object is controlled by the {@code getObject}
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* method, which invokes the
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* {@code checkGuard} method on the Guard object that is
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* guarding access. If access is not allowed,
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* an exception is thrown.
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*
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* @see Guard
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* @see Permission
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*
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* @author Roland Schemers
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* @author Li Gong
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* @since 1.2
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*/
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public class GuardedObject implements java.io.Serializable {
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private static final long serialVersionUID = -5240450096227834308L;
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private Object object; // the object we are guarding
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private Guard guard; // the guard
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/**
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* Constructs a GuardedObject using the specified object and guard.
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* If the Guard object is null, then no restrictions will
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* be placed on who can access the object.
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*
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* @param object the object to be guarded.
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*
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* @param guard the Guard object that guards access to the object.
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*/
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public GuardedObject(Object object, Guard guard)
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{
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this.guard = guard;
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this.object = object;
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}
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/**
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* Retrieves the guarded object, or throws an exception if access
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* to the guarded object is denied by the guard.
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*
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* @return the guarded object.
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*
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* @exception SecurityException if access to the guarded object is
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* denied.
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*/
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public Object getObject()
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throws SecurityException
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{
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if (guard != null)
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guard.checkGuard(object);
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return object;
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}
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/**
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* Writes this object out to a stream (i.e., serializes it).
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* We check the guard if there is one.
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*/
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private void writeObject(java.io.ObjectOutputStream oos)
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throws java.io.IOException
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{
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if (guard != null)
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guard.checkGuard(object);
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oos.defaultWriteObject();
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}
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}
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