线程与观察者模式-优快云博客

本文介绍了一个使用Java实现的任务分配场景，通过观察者模式来通知主线程各个子线程的完成状态。四个子线程分别执行制卡任务，并在完成后通知Action对象更新计数。

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场景，某action把任务分配给N个线程，当线程完成后通知action，action返回。

package com.koubei.Observable;

import java.util.Observable;
import java.util.Observer;

public class Action implements Observer{

    private int count;
    
    public String execute() throws InterruptedException{
        
        new Thread(new MadeCardThread(10,this)).start();
        new Thread(new MadeCardThread(10,this)).start();
        new Thread(new MadeCardThread(10,this)).start();
        new Thread(new MadeCardThread(10,this)).start();
        
        while(count != 40){
            Thread.sleep(1000);
        }
        System.out.println("========= end =========");
        return "success";
    }

    
    public void update(Observable o, Object arg) {
        // TODO Auto-generated method stub
        if(arg instanceof Integer){
            count = count + (Integer)arg;
        }
    }
    
    public static void main(String[] args) throws InterruptedException {
        (new Action()).execute();
    }
}

class MadeCardThread extends Observable implements Runnable {

    private int count;
    
    
    public MadeCardThread(int count,Observer observer){
        this.addObserver(observer);
        this.count = count;
    }
    
    public void run() {
        // TODO Auto-generated method stub
        for(int i=0; i<count; i++){
            System.out.println(Thread.currentThread().getId() + " : " + i);
        }
        this.setChanged();
        this.notifyObservers(count);
    }
    
}