JDK中ExecutorService，Callable，Future对线程的支持

1、代码背景：

    假如有Thread1、Thread2、Thread3、Thread4四条线程分别统计C、D、E、F四个盘的大小，所有线程都统计完毕交给Thread5线程去做汇总，应当如何实现？

2、代码：

    统计“盘子”大小的代码，此处实现jdk中的Callable接口，

package com.wang.test.concurrent;

import java.util.concurrent.Callable;

public class Task1 implements Callable<Integer> {

	private int x;
	private int y;
	
	public Task1(int x, int y) {
		this.x = x;
		this.y = y;
	}

	@Override
	public Integer call() throws Exception {
		return x*y;
	}

}

    统计汇总的代码，也是实现jdk中的Callable接口，

package com.wang.test.concurrent;

import java.util.concurrent.Callable;

public class Task2 implements Callable<Integer> {

	private int x;
	private int y;
	private int q;
	private int w;
	
	public Task2(int x, int y, int q, int w) {
		this.x = x;
		this.y = y;
		this.q = q;
		this.w = w;
	}

	@Override
	public Integer call() throws Exception {
		return x + y + q + w;
	}

}

      客户端：使用JDK中Executors.newFixedThreadPool方法创建ExecutorService，ExecutorService的submit方法接收Callable接口的实现，JDK内部将弄成线程处理，使用Future接收submit方法的返回值，当future调用get方法时，如果线程还没有执行完，程序阻塞在这里，知道线程执行完。

package com.wang.test.concurrent;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class Client {

	public static void main(String[] args) throws Exception {
		ExecutorService pool = Executors.newFixedThreadPool(4);

		Task1 t1 = new Task1(1,2);
		Task1 t2 = new Task1(23,34);
		Task1 t3 = new Task1(23,456);
		Task1 t4 = new Task1(3,33);
		Future<Integer> f1 = pool.submit(t1);
		Future<Integer> f2 = pool.submit(t2);
		Future<Integer> f3 = pool.submit(t3);
		Future<Integer> f4 = pool.submit(t4);
		
		//Future调用get方法时，如果线程还没有执行完，程序阻塞在这里
		Task2 t5 = new Task2(f1.get(), f2.get(), f3.get(), f4.get());
		Future<Integer> f5 = pool.submit(t5);
		
		System.out.println(f5.get());
		
		pool.shutdown();
	}
}