詳解JDK中ExecutorService與Callable和Future對線程的支持
1、代碼背景：
假如有Thread1、Thread2、Thread3、Thread4四條線程分別統計C、D、E、F四個盤的大小，所有線程都統計完畢交給Thread5線程去做匯總，應當如何實現？
2、代碼：
統計“盤子”大小的代碼，此處實現jdk中的Callable接口，
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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; } } |
統計匯總的代碼，也是實現jdk中的Callable接口，
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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; } } |
客戶端：使用JDK中Executors.newFixedThreadPool方法創建ExecutorService，ExecutorService的submit方法接收Callable接口的實現，JDK內部將弄成線程處理，使用Future接收submit方法的返回值，當future調用get方法時，如果線程還沒有執行完，程序阻塞在這里，知道線程執行完。
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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調用get方法時，如果線程還沒有執行完，程序阻塞在這里 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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原文鏈接：http://hejiawangjava.iteye.com/blog/2393827
