my java note ---- 事件机制

# java 事件(java Event)
# java.util.Eventobject,java.util.EventListener
# victor
# 2016.06.16

Java 事件处理机制

java中的事件机制的参与者有3种角色：
    1. event object：事件状态对象,是一类事件的实例。
        伴随着事件的发生，相应的状态通常都封装在事件状态对象中，该对象必须继承自java.util.EventObject。事件状态对象作为单参传递给应响应该事件的监听者方法中。
    2. event source：具体的事件源,事件的生产者。
        发出某种特定事件的事件源的标识是：遵从规定的设计格式为事件监听者定义注册方法，并接受对指定事件监听者接口实例的引用。
    3. event listener：事件监听者,事件的消费者。
        具体的对监听的事件类，当它监听到event object产生的时候，它就调用相应的方法，进行处理。

<Note>
    public interface EventListener：所有事件侦听器接口必须扩展的标记接口。
    public class EventObject extends Object implements Serializable。所有事件状态对象都将从其派生的根类。 所有 Event 在构造时都引用了对象 "source"，在逻辑上认为该对象是最初发生有关 Event 的对象。

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运行结果：

Console>> Console is started.
lights>> lights are changing.
Light 0>> is off
Light 1>> is off
Light 2>> is on
Light 3>> is off
Light 4>> is on
Light 5>> is on
Light 6>> is off
Light 7>> is on
Light 8>> is on
Light 9>> is on
lights>> lights are changing.
Light 0>> is on
Light 1>> is on
Light 2>> is on
Light 3>> is on
Light 4>> is off
Light 5>> is on
Light 6>> is on
Light 7>> is off
Light 8>> is on
Light 9>> is off

OUTPUT

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JAVA CODE：

1. 定义事件对象

package event;

import java.util.EventObject;

public class LightEvent extends EventObject {

    private static final long serialVersionUID = -1256654879784096588L;
    private boolean lightstate = false;
    private String lightname;

    public String getLightname() {
        return lightname;
    }

    public boolean getLightstate() {
        return lightstate;
    }

    public LightEvent(Object source,String name,boolean state) {
        super(source);
        this.lightstate = state;
        this.lightname = name;
    }

}

Event Class

2. 定义事件监听接口和具体的监听者类

package event;

import java.util.EventListener;

public interface lightlistener extends EventListener {
    public abstract void listenlight (LightEvent event);
}

package event;

public class lightlistener1 implements lightlistener{
    public void listenlight (LightEvent event){
        if(event.getLightstate()){
            System.out.println(""+event.getLightname()+">> is on");
        }
        else{
            System.out.println(""+event.getLightname()+">> is off");
        }
    };

}

Listener interface & Concrete listener

3. 定义事件源和注册类

//register
package event;

import java.util.*;

public class listenerregister {
    public List<EventListener> listenerlist = new ArrayList<EventListener>();

    public void addListener(EventListener listener) {
        listenerlist.add(listener);
    }

    public void removeListener(EventListener listener) {
        listenerlist.remove(listener);
    }

    public void notifylisteners(LightEvent event){
        for(EventListener tmplistener : listenerlist){
            ((lightlistener)tmplistener).listenlight(event);
        }
    }
}

// EventSource
package event;

import java.util.*;

public class Console {
    private listenerregister register = new listenerregister();
    private boolean[] lights = new boolean[10] ;
    private Random randomer = new Random();

    public void setLights(boolean light, int index) {
        this.lights[index] = light;
        String name = "Light "+ index;
        LightEvent event = new LightEvent(this,name,light);
        notifylisteners(event);
    }

    public void notifylisteners(LightEvent event){
        register.notifylisteners(event);
    }

    public void addListener(EventListener listener) {
        register.listenerlist.add(listener);
    }

    public void removeListener(EventListener listener) {
        register.listenerlist.remove(listener);
    }

    public static void main(String[] args) throws InterruptedException {
        // TODO Auto-generated method stub
        System.out.println("Console>> Console is started.");
        Console console = new Console();
        console.addListener(new lightlistener1());
        while(true){
            System.out.println("lights>> lights are changing.");
            for(int i=0;i<10;i++){
                console.setLights(console.randomer.nextBoolean(), i);
            }
            Thread.sleep(1000);
        }
    }
}

EventSource & Register