Java回调实现

Java回调实现

 

有个这样的问题：老板（Boss）让工人（Worker）干完活告诉他干的情况如何。

 

实际上是一个典型的回调问题，Java实现如下：

 

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

 

/**
* Created by IntelliJ IDEA.
* User: leizhimin
* Date: 2008-7-31 13:18:21
* 事件B
*/
public class EventB implements Event{
    /**
     * 返回发生事件信息
     * @return 事件信息
     */
    public String happendEvent() {
        return "发生了事件 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;      //工人所属的老板

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

    /**
     * 干活
     */
    public void doWork() {
        System.out.println(name + " is doing working...");
        //工人挺辛苦，干着枯燥乏味的重复工作，哈哈
        for (int i = 0; i < 2000000; i++) {
            int x = i / 234 + 234;
        }
        System.out.println(name + " was finished work.");
        //向老板说明发生的情况
        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
* 老板
*/
public class Boss {
    private String name;

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

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

 

/**
* Created by IntelliJ IDEA.
* User: leizhimin
* Date: 2008-7-31 13:35:38
* 测试类
*/
public class Test {
    public static void main(String args[]){
        //初始化老板和工人
        Boss boss = new Boss("老板");
        Worker worker1= new Worker("张三",boss);
        Worker worker2= new Worker("李四",boss);

        //捏造两个事件
        Event event1 = new EventA();
        Event event2 = new EventB();

        //事件是工人发出的
        worker1.setEvent(event1);
        worker2.setEvent(event2);

        //工人干活，干完了通知老板干的情况如何
        worker1.doWork();
        worker2.doWork();

    }
}

 

运行结果：

张三 is doing working...
张三 was finished work.
老板接收到事件信息： 张三: 发生了事件 EventA！
李四 is doing working...
李四 was finished work.
老板接收到事件信息： 李四: 发生了事件 EventB！

Process finished with exit code 0

 

呵呵，工人干活完成后，自动将发生的事件汇报给老板。

 

当然，如果工人很多，每个人都汇报的话，老板肯定会烦，那么老板可能会下达，发生了严重问题的员工才需要汇报问题。这个时候，需要做个事件过滤。