propertychangemulticaster.java

采用 Java 编写的数据库系统单元测试程序。

        child = (PropertyChangeMulticaster)children.get(propertyName);
      
      if (child == null) {
        child = new PropertyChangeMulticaster(source);
        children.put(propertyName, child);
      }
    }

    child.addPropertyChangeListener(listener);
  }

  /**
   * Add a PropertyChangeListener for a specific property, if it is not
   * already registered.  The listener
   * will be invoked only when a call on firePropertyChange names that
   * specific property. 
   *
   * @param propertyName  The name of the property to listen on.
   * @param listener  The PropertyChangeListener to be added
   * @exception NullPointerException If listener is null
   */
  
  public void addPropertyChangeListenerIfAbsent(String propertyName,
                                        PropertyChangeListener listener) {
        logger.debug("addPropertyChangeListenerIfAbsent(propertyName=" + propertyName + ", listener=" + listener
                + ") - start");

    if (listener == null) throw new NullPointerException();

    PropertyChangeMulticaster child = null;

    synchronized(this) {
      if (children == null) 
        children = new HashMap();
      else 
        child = (PropertyChangeMulticaster)children.get(propertyName);
      
      if (child == null) {
        child = new PropertyChangeMulticaster(source);
        children.put(propertyName, child);
      }
    }

    child.addPropertyChangeListenerIfAbsent(listener);
  }

  /**
   * Remove a PropertyChangeListener for a specific property.
   * Affects only the given property. 
   * If the listener is also registered for all properties,
   * then it will continue to be registered for them.
   *
   * @param propertyName  The name of the property that was listened on.
   * @param listener  The PropertyChangeListener to be removed
   */
  
  public void removePropertyChangeListener(String propertyName,
                                           PropertyChangeListener listener) {
        logger.debug("removePropertyChangeListener(propertyName=" + propertyName + ", listener=" + listener
                + ") - start");

    PropertyChangeMulticaster child = getChild(propertyName);
    if (child != null) 
      child.removePropertyChangeListener(listener);
  }


  /**
   * Helper method to relay evt to all listeners. 
   * Called by all public firePropertyChange methods.
   **/

  protected void multicast(PropertyChangeEvent evt) {
        logger.debug("multicast(evt=" + evt + ") - start");

    PropertyChangeListener[] array;  // bind in synch block below
    PropertyChangeMulticaster child = null;

    synchronized (this) {
      array = listeners;

      if (children != null && evt.getPropertyName() != null)
        child = (PropertyChangeMulticaster)children.get(evt.getPropertyName());
    }
    
    for (int i = 0; i < array.length; ++i) 
      array[i].propertyChange(evt);
    
    if (child != null) 
      child.multicast(evt);

  }

  
  /**
   * Report a bound property update to any registered listeners.
   * No event is fired if old and new are equal and non-null.
   *
   * @param propertyName  The programmatic name of the property
   *		that was changed.
   * @param oldValue  The old value of the property.
   * @param newValue  The new value of the property.
   */
  public void firePropertyChange(String propertyName, 
                                 Object oldValue, Object newValue) {
        logger.debug("firePropertyChange(propertyName=" + propertyName + ", oldValue=" + oldValue + ", newValue="
                + newValue + ") - start");
   
    if (oldValue == null || newValue == null || !oldValue.equals(newValue)) {
      multicast(new PropertyChangeEvent(source,
                                        propertyName, 
                                        oldValue, 
                                        newValue));
    }
    
  }

  /**
   * Report an int bound property update to any registered listeners.
   * No event is fired if old and new are equal and non-null.
   * <p>
   * This is merely a convenience wrapper around the more general
   * firePropertyChange method that takes Object values.
   *
   * @param propertyName  The programmatic name of the property
   *		that was changed.
   * @param oldValue  The old value of the property.
   * @param newValue  The new value of the property.
   */
  public void firePropertyChange(String propertyName, 
                                 int oldValue, int newValue) {
        logger.debug("firePropertyChange(propertyName=" + propertyName + ", oldValue=" + oldValue + ", newValue="
                + newValue + ") - start");

    if (oldValue != newValue) {
      multicast(new PropertyChangeEvent(source,
                                        propertyName, 
                                        new Integer(oldValue), 
                                        new Integer(newValue)));
    }
  }


  /**
   * Report a boolean bound property update to any registered listeners.
   * No event is fired if old and new are equal and non-null.
   * <p>
   * This is merely a convenience wrapper around the more general
   * firePropertyChange method that takes Object values.
   *
   * @param propertyName  The programmatic name of the property
   *		that was changed.
   * @param oldValue  The old value of the property.
   * @param newValue  The new value of the property.
   */
  public void firePropertyChange(String propertyName, 
                                 boolean oldValue, boolean newValue) {
        logger.debug("firePropertyChange(propertyName=" + propertyName + ", oldValue=" + oldValue + ", newValue="
                + newValue + ") - start");

    if (oldValue != newValue) {
      multicast(new PropertyChangeEvent(source,
                                        propertyName, 
                                        new Boolean(oldValue), 
                                        new Boolean(newValue)));
    }
  }

  /**
   * Fire an existing PropertyChangeEvent to any registered listeners.
   * No event is fired if the given event's old and new values are
   * equal and non-null.
   * @param evt  The PropertyChangeEvent object.
   */
  public void firePropertyChange(PropertyChangeEvent evt) {
        logger.debug("firePropertyChange(evt=" + evt + ") - start");

    Object oldValue = evt.getOldValue();
    Object newValue = evt.getNewValue();
    if (oldValue == null || newValue == null || !oldValue.equals(newValue)) 
      multicast(evt);
  }

  /**
   * Check if there are any listeners for a specific property.
   * If propertyName is null, return whether there are any listeners at all.
   *
   * @param propertyName  the property name.
   * @return true if there are one or more listeners for the given property
   * 
   */
  public boolean hasListeners(String propertyName) {
        logger.debug("hasListeners(propertyName=" + propertyName + ") - start");

    PropertyChangeMulticaster child;

    synchronized (this) {
      if (listeners.length > 0)
        return true;
      else if (propertyName == null || children == null)
        return false;
      else {
        child = (PropertyChangeMulticaster)children.get(propertyName);
        if (child == null)
          return false;
      }
    }
    
    return child.hasListeners(null);
  }


  /**
   * @serialData Null terminated list of <code>PropertyChangeListeners</code>.
   * <p>
   * At serialization time we skip non-serializable listeners and
   * only serialize the serializable listeners.
   *
   */
  private synchronized void writeObject(ObjectOutputStream s) throws IOException {
        logger.debug("writeObject(s=" + s + ") - start");

    s.defaultWriteObject();
    
    for (int i = 0; i < listeners.length; i++) {      
      if (listeners[i] instanceof Serializable) {
        s.writeObject(listeners[i]);
      }
    }
    s.writeObject(null);
  }
  
  
  private void readObject(ObjectInputStream s) throws ClassNotFoundException, IOException {
        logger.debug("readObject(s=" + s + ") - start");

    listeners = new PropertyChangeListener[0];     // paranoically reset
    s.defaultReadObject();
    
    Object listenerOrNull;
    while (null != (listenerOrNull = s.readObject())) {
      addPropertyChangeListener((PropertyChangeListener)listenerOrNull);
    }
  }

}