Java中的FutureTask实现代码实例

public class ThreadTest_Demo {
    static ExecutorService executors = Executors.newScheduledThreadPool(2);
    public ThreadTest_Demo() {
    }
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        Callable<String> callable = new Callable<String>() {
            public String call() throws Exception {
                String str = "返回某个数据!";
                return str;
            }
        };
        Future<String> submit = executors.submit(callable);
        KaneFutureTask<String> futureTask = new KaneFutureTask(callable);
        (new Thread(futureTask)).start();
        System.out.println((String)futureTask.get());
    }
}

public class KaneFutureTask<T> implements Runnable {
    private Callable<T> callable;
    T result;//返回的结果
    volatile String state = "NEW";//线程执行的状态
    LinkedBlockingQueue<Thread> waiters = new LinkedBlockingQueue();//存储等待结果的线程
    public KaneFutureTask(Callable<T> callable) {
        this.callable = callable;
    }
	//run()方法未执行未必,阻塞
    public T get() {
        if ("END".equals(this.state)) {
            return this.result;
        } else {
            while(!"END".equals(this.state)) {//这里开始阻塞
            	//把线程存放到容器中
                this.waiters.offer(Thread.currentThread());
                //阻塞
                LockSupport.park();
            }
            return this.result;
        }
    }
    public void run() {
        try {
        	//执行Callable的call方法
            this.result = this.callable.call();
        } catch (Exception var5) {
            var5.printStackTrace();
        } finally {
        	//线程状态修改
            this.state = "END";
        }
		//从容器中取出当前线程
		Thread waiter = (Thread)this.waiters.poll();
        for(waiter != null) {
        	//取消阻塞
            LockSupport.unpark(waiter);
            waiter = (Thread)this.waiters.poll()
        }
    }
}