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

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  30
  31 package com.sun.star.lib.uno.helper;
  32 import com.sun.star.lang.XComponent;
  33 import com.sun.star.lang.XEventListener;
  34 import com.sun.star.lang.EventObject;
  35 import com.sun.star.uno.Type;
  36
  37 /** This class can be used as the base class for UNO components. In addition to the functionality ,which
  38  *  is inherited from WeakBase, it implements com.sun.star.lang.XComponent.
  39  */
  40 public class ComponentBase extends WeakBase implements XComponent
  41 {
  42     private final boolean DEBUG= false;
  43     protected MultiTypeInterfaceContainer listenerContainer;
  44     protected boolean bInDispose= false;
  45     protected boolean bDisposed= false;
  46     static final Type  EVT_LISTENER_TYPE= new Type(XEventListener.class);
  47
  48
  49     /** Creates a new instance of CompBase */
  50     public ComponentBase()
  51     {
  52         super();
  53         listenerContainer= new MultiTypeInterfaceContainer();
  54     }
  55
  56     /** Override to perform extra clean-up work. Provided for subclasses. It is
  57         called during dispose()
  58      */
  59     protected void preDisposing()
  60     {
  61     }
  62     /** Override to become notified right before the disposing action is performed.
  63      */
  64     protected void postDisposing()
  65     {
  66     }
  67
  68
  69     /** Method of XComponent. It is called by the owning client when the component is not needed
  70      *  anymore. The registered listeners are notified that this method has been called.
  71      */
  72     public void dispose()
  73     {
  74         // Determine in a thread-safe way if this is the first call to this method.
  75         // Only then we proceed with the notification of event listeners.
  76         // It is an error to call this method more then once.
  77         boolean bDoDispose= false;
  78         synchronized (this)
  79         {
  80             if ( ! bInDispose && ! bDisposed)
  81             {
  82                 bDoDispose= true;
  83                 bInDispose= true;
  84             }
  85         }
  86         // The notification occures in an unsynchronized block in order to avoid
  87         // deadlocks if one of the listeners calls back in a different thread on
  88         // a synchronized method which uses the same object.
  89         if (bDoDispose)
  90         {
  91             try
  92             {
  93                 preDisposing();
  94                 listenerContainer.disposeAndClear(new EventObject(this));
  95                 //notify subclasses that disposing is in progress
  96                 postDisposing();
  97             }
  98             finally
  99             {
 100                 // finally makes sure that the  flags are set even if a RuntimeException is thrown.
 101                 // That ensures that this function is only called once.
 102                 bDisposed= true;
 103                 bInDispose= false;
 104             }
 105         }
 106         else
 107         {
 108             // in a multithreaded environment, it can't be avoided, that dispose is called twice.
 109             // However this condition is traced, because it MAY indicate an error.
 110             if (DEBUG)
 111                 System.out.println("OComponentHelper::dispose() - dispose called twice" );
 112         }
 113     }
 114
 115     /** Method of XComponent.
 116      */
 117     public void removeEventListener(XEventListener xEventListener)
 118     {
 119         listenerContainer.removeInterface( EVT_LISTENER_TYPE, xEventListener);
 120     }
 121
 122     public void addEventListener(XEventListener listener)
 123     {
 124         boolean bDoDispose= false;
 125         synchronized (this)
 126         {
 127             if (bDisposed || bInDispose)
 128                 bDoDispose= true;
 129             else
 130                listenerContainer.addInterface(EVT_LISTENER_TYPE, listener);
 131         }
 132         if (bDoDispose )
 133         {
 134             listener.disposing( new EventObject(this));
 135         }
 136     }
 137
 138     protected void finalize() throws Throwable
 139     {
 140         if ( ! bInDispose && ! bDisposed)
 141             dispose();
 142         super.finalize();
 143     }
 144 }