JDK ExecutorService 详解JDK中ExecutorService与Callable和Future对线程的支持
莫欺少年穷Java 人气:0想了解详解JDK中ExecutorService与Callable和Future对线程的支持的相关内容吗,莫欺少年穷Java在本文为您仔细讲解JDK ExecutorService的相关知识和一些Code实例,欢迎阅读和指正,我们先划重点:JDK,ExecutorService,JDK中ExecutorService与Callable和Future对线程的支持,下面大家一起来学习吧。
详解JDK中ExecutorService与Callable和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(); } }
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