1 files changed, 102 insertions, 0 deletions
diff --git a/javaunohelper/com/sun/star/lib/uno/helper/WeakAdapter.java b/javaunohelper/com/sun/star/lib/uno/helper/WeakAdapter.java
new file mode 100644
index 000000000000..2c3cc142f1a5
--- /dev/null
+++ b/javaunohelper/com/sun/star/lib/uno/helper/WeakAdapter.java
@@ -0,0 +1,102 @@
+/*************************************************************************
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * Copyright 2000, 2010 Oracle and/or its affiliates.
+ *
+ * OpenOffice.org - a multi-platform office productivity suite
+ *
+ * This file is part of OpenOffice.org.
+ *
+ * OpenOffice.org is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 3
+ * only, as published by the Free Software Foundation.
+ *
+ * OpenOffice.org 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 Lesser General Public License version 3 for more details
+ * (a copy is included in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * version 3 along with OpenOffice.org.  If not, see
+ * <http://www.openoffice.org/license.html>
+ * for a copy of the LGPLv3 License.
+ *
+ ************************************************************************/
+
+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 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
+{
+    private final boolean DEBUG= false;
+    // references the XWeak implementation
+    private WeakReference m_weakRef;
+    // contains XReference objects registered by addReference
+    private List m_xreferenceList;
+
+    /**
+     *@param component the object that is to be held weak
+     */
+    public WeakAdapter(Object component)
+    {
+        m_weakRef= new WeakReference(component);
+        m_xreferenceList= Collections.synchronizedList( new LinkedList());
+    }
+
+    /** Called by the XWeak implementation (WeakBase) when it is being finalized.
+     *  It is only being called once.
+     *  The registererd 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 multithreaded
+     *  environment.
+     */
+    void referentDying()
+    {
+        //synchronized call
+        Object[] references= m_xreferenceList.toArray();
+        for (int i= references.length; i > 0; i--)
+        {
+            ((XReference) 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 a listener
+     */
+    public void addReference(XReference xReference)
+    {
+        m_xreferenceList.add(xReference);
+    }
+}
+