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Java中的事件机制在这里回顾和总结下。

1.事件对象

import java.util.EventObject;public class DoorEvent extends EventObject{		/**	 * Door open and close event	 */	private static final long serialVersionUID = 1L;	private String doorState = "";		public DoorEvent(Object source,String state) {		super(source);		// TODO Auto-generated constructor stub		this.doorState = state;	}	public void setDoorState(String doorstate){		this.doorState = doorstate;	}		public String getDoorState(){		return this.doorState;	}}

import java.util.EventListener;public interface DoorListener extends EventListener {	public void doorEvent(DoorEvent event);}

public class MyDoorListener1 implements DoorListener{	@Override	public void doorEvent(DoorEvent event) {		// TODO Auto-generated method stub		if(event.getDoorState() == "open"){			System.out.println("door1 opened.");		}else{			System.out.println("door1 closed");		}	}}

public class MyDoorListener2 implements DoorListener{	@Override	public void doorEvent(DoorEvent event) {		// TODO Auto-generated method stub		if(event.getDoorState() == "open"){			System.out.println("door2 opened.");		}else{			System.out.println("door2 closed");		}	}}

Manager角色负责发布事件，Listener负责监听。

import java.util.Collection;import java.util.HashSet;import java.util.Iterator;public class DoorManager {		private Collection listeners;		public void addDoorListener(DoorListener listener){		if(listeners == null){			listeners = new HashSet();		}		listeners.add(listener);	}		public void removeListener(DoorListener listener){		if(listeners == null) return;		listeners.remove(listener);	}		public void fireDoorOpenEvent(){		if(listeners == null) return;		DoorEvent event = new DoorEvent(this,"open");		notifyListeners(event);	}		public void fireDoorCloseEvent(){		if(listeners == null) return;		DoorEvent event = new DoorEvent(this,"close");		notifyListeners(event);	}		private void notifyListeners(DoorEvent event) {        Iterator iter = listeners.iterator();        while (iter.hasNext()) {            DoorListener listener = (DoorListener) iter.next();            listener.doorEvent(event);        }    }}

public class Hello {	/**	 * @param args	 */	public static void main(String[] args) {		// TODO Auto-generated method stub		DoorManager manager = new DoorManager();		manager.addDoorListener(new MyDoorListener1());		manager.addDoorListener(new MyDoorListener2());				manager.fireDoorOpenEvent();		System.out.println("I am in.");		manager.fireDoorCloseEvent();	}}

door1 opened.door2 opened.I am in.door1 closeddoor2 closed

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