ridljar/com/sun/star/lib/uno/helper/ComponentBase.java

   1 /*
   2  * This file is part of the LibreOffice project.
   3  *
   4  * This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   7  *
   8  * This file incorporates work covered by the following license notice:
   9  *
  10  *   Licensed to the Apache Software Foundation (ASF) under one or more
  11  *   contributor license agreements. See the NOTICE file distributed
  12  *   with this work for additional information regarding copyright
  13  *   ownership. The ASF licenses this file to you under the Apache
  14  *   License, Version 2.0 (the "License"); you may not use this file
  15  *   except in compliance with the License. You may obtain a copy of
  16  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  17  */
  18
  19 package com.sun.star.lib.uno.helper;
  20 import com.sun.star.lang.XComponent;
  21 import com.sun.star.lang.XEventListener;
  22 import com.sun.star.lang.EventObject;
  23 import com.sun.star.uno.Type;
  24
  25 /** This class can be used as the base class for UNO components. In addition to the functionality ,which
  26  *  is inherited from WeakBase, it implements com.sun.star.lang.XComponent.
  27  */
  28 public class ComponentBase extends WeakBase implements XComponent
  29 {
  30     private static final boolean DEBUG= false;
  31     protected MultiTypeInterfaceContainer listenerContainer;
  32     protected boolean bInDispose= false;
  33     protected boolean bDisposed= false;
  34     static final Type  EVT_LISTENER_TYPE= new Type(XEventListener.class);
  35
  36
  37     /** Creates a new instance of CompBase */
  38     public ComponentBase()
  39     {
  40         super();
  41         listenerContainer= new MultiTypeInterfaceContainer();
  42     }
  43
  44     /** Override to perform extra clean-up work. Provided for subclasses. It is
  45         called during dispose()
  46      */
  47     protected void preDisposing()
  48     {
  49     }
  50     /** Override to become notified right before the disposing action is performed.
  51      */
  52     protected void postDisposing()
  53     {
  54     }
  55
  56
  57     /** Method of XComponent. It is called by the owning client when the component is not needed
  58      *  anymore. The registered listeners are notified that this method has been called.
  59      */
  60     public void dispose()
  61     {
  62         // Determine in a thread-safe way if this is the first call to this method.
  63         // Only then we proceed with the notification of event listeners.
  64         // It is an error to call this method more than once.
  65         boolean bDoDispose= false;
  66         synchronized (this)
  67         {
  68             if ( ! bInDispose && ! bDisposed)
  69             {
  70                 bDoDispose= true;
  71                 bInDispose= true;
  72             }
  73         }
  74         // The notification occurs in an unsynchronized block in order to avoid
  75         // deadlocks if one of the listeners calls back in a different thread on
  76         // a synchronized method which uses the same object.
  77         if (bDoDispose)
  78         {
  79             try
  80             {
  81                 preDisposing();
  82                 listenerContainer.disposeAndClear(new EventObject(this));
  83                 //notify subclasses that disposing is in progress
  84                 postDisposing();
  85             }
  86             finally
  87             {
  88                 // finally makes sure that the  flags are set even if a RuntimeException is thrown.
  89                 // That ensures that this function is only called once.
  90                 synchronized (this)
  91                 {
  92                     bDisposed= true;
  93                     bInDispose= false;
  94                 }
  95             }
  96         }
  97         else
  98         {
  99             // in a multithreaded environment, it can't be avoided, that dispose is called twice.
 100             // However this condition is traced, because it MAY indicate an error.
 101             if (DEBUG)
 102                 System.out.println("OComponentHelper::dispose() - dispose called twice" );
 103         }
 104     }
 105
 106     /** Method of XComponent.
 107      */
 108     public void removeEventListener(XEventListener xEventListener)
 109     {
 110         listenerContainer.removeInterface( EVT_LISTENER_TYPE, xEventListener);
 111     }
 112
 113     public void addEventListener(XEventListener listener)
 114     {
 115         boolean bDoDispose= false;
 116         synchronized (this)
 117         {
 118             if (bDisposed || bInDispose)
 119                 bDoDispose= true;
 120             else
 121                listenerContainer.addInterface(EVT_LISTENER_TYPE, listener);
 122         }
 123         if (bDoDispose )
 124         {
 125             listener.disposing( new EventObject(this));
 126         }
 127     }
 128
 129     @Override
 130     protected void finalize() throws Throwable
 131     {
 132         if ( ! bInDispose && ! bDisposed)
 133             dispose();
 134         super.finalize();
 135     }
 136 }