beancontextabstractplugin.java

来自「OpenMap是一个基于JavaBeansTM的开发工具包。利用OpenMap你」· Java 代码 · 共 215 行

// **********************************************************************
// 
// <copyright>
// 
//  BBN Technologies
//  10 Moulton Street
//  Cambridge, MA 02138
//  [phone]
// 
//  Copyright (C) BBNT Solutions LLC. All rights reserved.
// 
// </copyright>
// **********************************************************************
// 
// $Source: /cvs/distapps/openmap/src/openmap/com/bbn/openmap/plugin/BeanContextAbstractPlugIn.java,v $
// $RCSfile: BeanContextAbstractPlugIn.java,v $
// $Revision: 1.4.2.2 $
// $Date: 2006/02/13 17:02:02 $
// $Author: dietrick $
// 
// **********************************************************************

package com.bbn.openmap.plugin;

import java.awt.Component;
import java.beans.PropertyChangeListener;
import java.beans.PropertyVetoException;
import java.beans.VetoableChangeListener;
import java.beans.beancontext.BeanContext;
import java.beans.beancontext.BeanContextChild;
import java.beans.beancontext.BeanContextChildSupport;
import java.beans.beancontext.BeanContextMembershipEvent;
import java.beans.beancontext.BeanContextMembershipListener;
import java.util.Iterator;

/**
 * This class is an abstract implementation of the PlugIn. It does all the
 * things the AbstractPlugIn does, but also carries the support baggage for
 * PlugIns that want to play in the BeanContext.
 * 
 * @see com.bbn.openmap.plugin.PlugInLayer
 * @see com.bbn.openmap.plugin.PlugIn
 * @see com.bbn.openmap.MapHandler
 * @see com.bbn.openmap.MapHandlerChild
 */
public abstract class BeanContextAbstractPlugIn extends AbstractPlugIn
        implements BeanContextChild, BeanContextMembershipListener {

    public BeanContextAbstractPlugIn() {
        super();
    }

    public BeanContextAbstractPlugIn(Component comp) {
        super(comp);
    }

    /**
     * BeanContextChildSupport object provides helper functions for
     * BeanContextChild interface.
     */
    protected BeanContextChildSupport beanContextChildSupport = new BeanContextChildSupport();

    /**
     * This is the method that your object can use to find other objects within
     * the MapHandler (BeanContext). This method gets called when the object
     * gets added to the MapHandler, or when another object gets added to the
     * MapHandler after the object is a member.
     * 
     * @param it Iterator to use to go through a list of objects. Find the ones
     *        you need, and hook yourself up.
     */
    public void findAndInit(Iterator it) {
        while (it.hasNext()) {
            findAndInit((Object) it.next());
        }
    }

    /**
     * The findAndInit method has been made non-abstract, because it now calls
     * this method for every object that is in the iterator it receives. This
     * lets subclasses call a method on super classes so they can handle their
     * needs as well.
     */
    public void findAndInit(Object obj) {}

    /**
     * BeanContextMembershipListener method. Called when a new object is added
     * to the BeanContext of this object.
     */
    public void childrenAdded(BeanContextMembershipEvent bcme) {
        findAndInit(bcme.iterator());
    }

    /**
     * BeanContextMembershipListener method. Called when a new object is removed
     * from the BeanContext of this object. For the Layer, this method doesn't
     * do anything. If your layer does something with the childrenAdded method,
     * or findAndInit, you should take steps in this method to unhook the layer
     * from the object used in those methods.
     */
    public void childrenRemoved(BeanContextMembershipEvent bcme) {
        Iterator it = bcme.iterator();
        while (it.hasNext()) {
            findAndUndo(it.next());
        }
    }

    /**
     * The childrenRemoved has been changed to go through its iterator to call
     * this method with every object. This lets subclasses call this method on
     * their super class, so it can handle what it needs to with objects it may
     * be interested in.
     */
    public void findAndUndo(Object obj) {
        // If we find that our PlugInLayer is being removed from MapHandler, we
        // should remove ourselves to allow proper cleanup.
        if (obj instanceof PlugInLayer
                && ((PlugInLayer) obj).getPlugIn() == this) {
            getBeanContext().remove(this);
        }
    }

    /** Method for BeanContextChild interface. */
    public BeanContext getBeanContext() {
        return beanContextChildSupport.getBeanContext();
    }

    /**
     * Method for BeanContextChild interface. Adds this object as a
     * BeanContextMembership listener, set the BeanContext in this objects
     * BeanContextSupport, and receives the initial list of objects currently
     * contained in the BeanContext.
     */
    public void setBeanContext(BeanContext in_bc) throws PropertyVetoException {

        if (in_bc != null) {
            in_bc.addBeanContextMembershipListener(this);
            beanContextChildSupport.setBeanContext(in_bc);
            findAndInit(in_bc.iterator());
        }
    }

    /**
     * Method for BeanContextChild interface. Uses the BeanContextChildSupport
     * to add a listener to this object's property. You don't need this function
     * for objects that extend java.awt.Component.
     */
    public void addPropertyChangeListener(String propertyName,
                                          PropertyChangeListener in_pcl) {
        beanContextChildSupport.addPropertyChangeListener(propertyName, in_pcl);
    }

    /**
     * Method for BeanContextChild interface. Uses the BeanContextChildSupport
     * to remove a listener to this object's property. You don't need this
     * function for objects that extend java.awt.Component.
     */
    public void removePropertyChangeListener(String propertyName,
                                             PropertyChangeListener in_pcl) {
        beanContextChildSupport.removePropertyChangeListener(propertyName,
                in_pcl);
    }

    /**
     * Method for BeanContextChild interface. Uses the BeanContextChildSupport
     * to add a listener to this object's property. This listener wants to have
     * the right to veto a property change.
     */
    public void addVetoableChangeListener(String propertyName,
                                          VetoableChangeListener in_vcl) {
        beanContextChildSupport.addVetoableChangeListener(propertyName, in_vcl);
    }

    /**
     * Method for BeanContextChild interface. Uses the BeanContextChildSupport
     * to remove a listener to this object's property. The listener has the
     * power to veto property changes.
     */
    public void removeVetoableChangeListener(String propertyName,
                                             VetoableChangeListener in_vcl) {
        beanContextChildSupport.removeVetoableChangeListener(propertyName,
                in_vcl);
    }

    /**
     * Method for BeanContextChild interface. Uses the BeanContextChildSupport
     * to fire a property change. You don't need this function for objects that
     * extend java.awt.Component.
     */
    public void firePropertyChange(String name, Object oldValue, Object newValue) {
        beanContextChildSupport.firePropertyChange(name, oldValue, newValue);
    }

    /**
     * Report a vetoable property update to any registered listeners. If anyone
     * vetos the change, then fire a new event reverting everyone to the old
     * value and then rethrow the PropertyVetoException.
     * <P>
     * 
     * No event is fired if old and new are equal and non-null.
     * <P>
     * 
     * @param name The programmatic name of the property that is about to change
     * 
     * @param oldValue The old value of the property
     * @param newValue - The new value of the property
     * 
     * @throws PropertyVetoException if the recipient wishes the property change
     *         to be rolled back.
     */
    public void fireVetoableChange(String name, Object oldValue, Object newValue)
            throws PropertyVetoException {
        beanContextChildSupport.fireVetoableChange(name, oldValue, newValue);
    }
}