Java回調實現

Java回調實現

 

有個這樣的問題：老闆（Boss）讓工人（Worker）幹完活告訴他乾的狀況如何。

 

其實是一個典型的回調問題，Java實現以下：

 

/**
* Created by IntelliJ IDEA.
* User: leizhimin
* Date: 2008-7-31 13:18:33
* 事件接口
*/
public interface Event {
     /**
     * 返回發生事件信息
     *
     * @return 事件信息
     */
     public String happendEvent();
}

 

/**
* Created by IntelliJ IDEA.
* User: leizhimin
* Date: 2008-7-31 13:18:14
* 事件A
*/
public class EventA implements Event {
     /**
     * 返回發生事件信息
     *
     * @return 事件信息
     */
     public String happendEvent() {
         return "發生了事件 EventA！";
    }
}

 

/**
* Created by IntelliJ IDEA.
* User: leizhimin
* Date: 2008-7-31 13:18:21
* 事件B
*/
public class EventB implements Event{
     /**
     * 返回發生事件信息
     * @return 事件信息
     */
     public String happendEvent() {
         return "發生了事件 EventB！";
    }
}

 

/**
* Created by IntelliJ IDEA.
* User: leizhimin
* Date: 2008-7-31 13:20:48
* 工人
*/
public class Worker {
     private Event event;     //事件
     private String name;     //工人姓名
     private Boss boss;       //工人所屬的老闆

     public Worker(String name, Boss boss) {
         this.name = name;
         this.boss = boss;
    }

     /**
     * 幹活
     */
     public void doWork() {
        System.out.println(name + " is doing working...");
         //工人挺辛苦，幹着枯燥乏味的重複工做，哈哈
         for ( int i = 0; i < 2000000; i++) {
             int x = i / 234 + 234;
        }
        System.out.println(name + " was finished work.");
         //向老闆說明發生的狀況
        boss.getWorkerEvent( this, event);
    }

     public Event getEvent() {
         return event;
    }

     public void setEvent(Event event) {
         this.event = event;
    }

     public String getName() {
         return name;
    }

     public void setName(String name) {
         this.name = name;
    }
}

 

/**
* Created by IntelliJ IDEA.
* User: leizhimin
* Date: 2008-7-31 13:26:22
* 老闆
*/
public class Boss {
     private String name;

     public Boss(String name) {
         this.name = name;
    }

     /**
     * 老闆接收工人的事件
     * @param worker 工人
     * @param event  事件
     */
     public void getWorkerEvent(Worker worker, Event event) {
        System.out.println( "老闆接收到事件信息： "+worker.getName() + ": " + event.happendEvent());
    }
}

 

/**
* Created by IntelliJ IDEA.
* User: leizhimin
* Date: 2008-7-31 13:35:38
* 測試類
*/
public class Test {
     public static void main(String args[]){
         //初始化老闆和工人
        Boss boss = new Boss( "老闆");
        Worker worker1= new Worker( "張三",boss);
        Worker worker2= new Worker( "李四",boss);

         //捏造兩個事件
        Event event1 = new EventA();
        Event event2 = new EventB();

         //事件是工人發出的
        worker1.setEvent(event1);
        worker2.setEvent(event2);

         //工人幹活，幹完了通知老闆乾的狀況如何
        worker1.doWork();
        worker2.doWork();

    }
}

 

運行結果：

張三 is doing working...
張三 was finished work.
老闆接收到事件信息： 張三: 發生了事件 EventA！
李四 is doing working...
李四 was finished work.
老闆接收到事件信息： 李四: 發生了事件 EventB！

Process finished with exit code 0

 

呵呵，工人幹活完成後，自動將發生的事件彙報給老闆。

 

固然，若是工人不少，每一個人都彙報的話，老闆確定會煩，那麼老闆可能會下達，發生了嚴重問題的員工才須要彙報問題。這個時候，須要作個事件過濾。 轉自http://lavasoft.blog.51cto.com/62575/90453