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Diffstat (limited to 'ridljar/com/sun/star/lib/uno/helper/WeakAdapter.java')
-rw-r--r-- | ridljar/com/sun/star/lib/uno/helper/WeakAdapter.java | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/ridljar/com/sun/star/lib/uno/helper/WeakAdapter.java b/ridljar/com/sun/star/lib/uno/helper/WeakAdapter.java new file mode 100644 index 000000000..67e01ac32 --- /dev/null +++ b/ridljar/com/sun/star/lib/uno/helper/WeakAdapter.java @@ -0,0 +1,94 @@ +/* + * This file is part of the LibreOffice project. + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. + * + * This file incorporates work covered by the following license notice: + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed + * with this work for additional information regarding copyright + * ownership. The ASF licenses this file to you under the Apache + * License, Version 2.0 (the "License"); you may not use this file + * except in compliance with the License. You may obtain a copy of + * the License at http://www.apache.org/licenses/LICENSE-2.0 . + */ + +package com.sun.star.lib.uno.helper; +import java.lang.ref.WeakReference; +import com.sun.star.uno.XAdapter; +import com.sun.star.uno.XReference; +import java.util.List; +import java.util.Collections; +import java.util.LinkedList; + +/** An XAdapter implementation that holds a weak reference (java.lang.ref.WeakReference) + * to an object. Clients can register listener (com.sun.star.lang.XReference) which + * are notified when the object (the one which is kept weak) is being finalized. That + * is, that object is being destroyed because there are not any hard references + * to it. + */ +public class WeakAdapter implements XAdapter +{ + // references the XWeak implementation + private final WeakReference<Object> m_weakRef; + // contains XReference objects registered by addReference + private final List<XReference> m_xreferenceList; + + /** + *@param component the object that is to be held weak + */ + public WeakAdapter(Object component) + { + m_weakRef= new WeakReference<Object>(component); + m_xreferenceList= Collections.synchronizedList( new LinkedList<XReference>()); + } + + /** Called by the XWeak implementation (WeakBase) when it is being finalized. + * It is only being called once. + * The registered XReference listeners are notified. On notification they are + * to unregister themselves. The notification is thread-safe. However, it is possible + * to add a listener during the notification process, which will never receive a + * notification. To prevent this, one would have to synchronize this method with + * the addReference method. But this can result in deadlocks in a multi-threaded + * environment. + */ + void referentDying() + { + //synchronized call + XReference[] references= m_xreferenceList.toArray(new XReference[m_xreferenceList.size()]); + for (int i= references.length; i > 0; i--) + { + references[i-1].dispose(); + } + } + + /** Method of com.sun.star.uno.XAdapter. It is called to obtain a hard reference + * to the object which is kept weak by this instance. + * @return hard reference to the object + */ + public Object queryAdapted() + { + return m_weakRef.get(); + } + + /** Method of com.sun.star.uno.XAdapter. Called by clients to register listener which + * are notified when the weak object is dying. + *@param xReference a listener + */ + public void removeReference(XReference xReference) + { + m_xreferenceList.remove(xReference); + } + + /** Method of com.sun.star.uno.XAdapter. Called by clients to unregister listeners. + *@param xReference listener + */ + public void addReference(XReference xReference) + { + m_xreferenceList.add(xReference); + } +} + |