102 lines
3.8 KiB
Java
102 lines
3.8 KiB
Java
/*************************************************************************
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*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* Copyright 2000, 2010 Oracle and/or its affiliates.
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*
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* OpenOffice.org - a multi-platform office productivity suite
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*
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* This file is part of OpenOffice.org.
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*
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* OpenOffice.org is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License version 3
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* only, as published by the Free Software Foundation.
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*
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* OpenOffice.org is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License version 3 for more details
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* (a copy is included in the LICENSE file that accompanied this code).
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*
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* You should have received a copy of the GNU Lesser General Public License
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* version 3 along with OpenOffice.org. If not, see
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* <http://www.openoffice.org/license.html>
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* for a copy of the LGPLv3 License.
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*
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************************************************************************/
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package com.sun.star.lib.uno.helper;
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import java.lang.ref.WeakReference;
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import com.sun.star.uno.XAdapter;
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import com.sun.star.uno.XReference;
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import java.util.List;
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import java.util.Collections;
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import java.util.LinkedList;
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/** An XAdapter implementation that holds a weak reference (java.lang.ref.WeakReference)
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* to an object. Clients can register listener (com.sun.star.lang.XReference) which
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* are notified when the the object (the one which is kept weak) is being finalized. That
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* is, that object is being destroyed because there are not any hard references
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* to it.
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*/
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public class WeakAdapter implements XAdapter
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{
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private final boolean DEBUG= false;
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// references the XWeak implementation
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private WeakReference m_weakRef;
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// contains XReference objects registered by addReference
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private List m_xreferenceList;
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/**
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*@param component the object that is to be held weak
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*/
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public WeakAdapter(Object component)
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{
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m_weakRef= new WeakReference(component);
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m_xreferenceList= Collections.synchronizedList( new LinkedList());
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}
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/** Called by the XWeak implementation (WeakBase) when it is being finalized.
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* It is only being called once.
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* The registererd XReference listeners are notified. On notification they are
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* to unregister themselves. The notification is thread-safe. However, it is possible
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* to add a listener during the notification process, which will never receive a
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* notification. To prevent this, one would have to synchronize this method with
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* the addReference method. But this can result in deadlocks in a multithreaded
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* environment.
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*/
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void referentDying()
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{
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//synchronized call
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Object[] references= m_xreferenceList.toArray();
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for (int i= references.length; i > 0; i--)
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{
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((XReference) references[i-1]).dispose();
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}
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}
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/** Method of com.sun.star.uno.XAdapter. It is called to obtain a hard reference
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* to the object which is kept weak by this instance.
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* @return hard reference to the object
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*/
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public Object queryAdapted()
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{
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return m_weakRef.get();
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}
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/** Method of com.sun.star.uno.XAdapter. Called by clients to register listener which
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* are notified when the weak object is dying.
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*@param xReference a listener
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*/
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public void removeReference(XReference xReference)
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{
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m_xreferenceList.remove(xReference);
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}
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/** Method of com.sun.star.uno.XAdapter. Called by clients to unregister listeners.
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*@param a listener
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*/
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public void addReference(XReference xReference)
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{
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m_xreferenceList.add(xReference);
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}
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}
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