Master和worker模式

让和hadoop的设计思想是一样的，Master负责分配任务和获取任务的结果，worker是真正处理业务逻辑的。

使用ConcurrentLikedQueue去承载所有的任务，因为会有多个worker会并发修改这个队列。

public class Task {

    private int id;
    private int price ;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public int getPrice() {
        return price;
    }
    public void setPrice(int price) {
        this.price = price;
    } 
    
}

public class Master {

    //1 有一个盛放任务的容器
    private ConcurrentLinkedQueue<Task> workQueue = new ConcurrentLinkedQueue<Task>();
    
    //2 需要有一个盛放worker的集合
    private HashMap<String, Thread> workers = new HashMap<String, Thread>();
    
    //3 需要有一个盛放每一个worker执行任务的结果集合
    private ConcurrentHashMap<String, Object> resultMap = new ConcurrentHashMap<String, Object>();
    
    //4 构造方法
    public Master(Worker worker , int workerCount){
        worker.setWorkQueue(this.workQueue);
        worker.setResultMap(this.resultMap);
        
        for(int i = 0; i < workerCount; i ++){
            this.workers.put(Integer.toString(i), new Thread(worker));
        }
        
    }
    
    //5 需要一个提交任务的方法
    public void submit(Task task){
        this.workQueue.add(task);
    }
    
    //6 需要有一个执行的方法，启动所有的worker方法去执行任务
    public void execute(){
        for(Map.Entry<String, Thread> me : workers.entrySet()){
            me.getValue().start();
        }
    }

    //7 判断是否运行结束的方法
    public boolean isComplete() {
        for(Map.Entry<String, Thread> me : workers.entrySet()){
            if(me.getValue().getState() != Thread.State.TERMINATED){
                return false;
            }
        }        
        return true;
    }

    //8 计算结果方法
    public int getResult() {
        int priceResult = 0;
        for(Map.Entry<String, Object> me : resultMap.entrySet()){
            priceResult += (Integer)me.getValue();
        }
        return priceResult;
    }
}

public class Worker implements Runnable {

    private ConcurrentLinkedQueue<Task> workQueue;
    private ConcurrentHashMap<String, Object> resultMap;
    
    public void setWorkQueue(ConcurrentLinkedQueue<Task> workQueue) {
        this.workQueue = workQueue;
    }

    public void setResultMap(ConcurrentHashMap<String, Object> resultMap) {
        this.resultMap = resultMap;
    }
    
    @Override
    public void run() {
        while(true){
            Task input = this.workQueue.poll();
            if(input == null) break;
            Object output = handle(input);
            this.resultMap.put(Integer.toString(input.getId()), output);
        }
    }

    private Object handle(Task input) {
        Object output = null;
        try {
            //处理任务的耗时。。 比如说进行操作数据库。。。
            Thread.sleep(500);
            output = input.getPrice();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return output;
    }



}

public class Main {

    public static void main(String[] args) {
        
        Master master = new Master(new Worker(), 20);
        
        Random r = new Random();
        for(int i = 1; i <= 100; i++){
            Task t = new Task();
            t.setId(i);
            t.setPrice(r.nextInt(1000));
            master.submit(t);
        }
        master.execute();
        long start = System.currentTimeMillis();
        
        while(true){
            if(master.isComplete()){
                long end = System.currentTimeMillis() - start;
                int priceResult = master.getResult();
                System.out.println("最终结果：" + priceResult + ", 执行时间：" + end);
                break;
            }
        }
        
    }
}