java多线程编程获取线程返回值：ExecutorCompletionService

最新推荐文章于 2024-05-19 12:36:34 发布

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最新推荐文章于 2024-05-19 12:36:34 发布

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分类专栏： Java

本文链接：https://blog.youkuaiyun.com/liuyong0818/article/details/8543159

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本文介绍了一个使用Java实现的简单并发下载任务管理系统。该系统通过固定大小的线程池执行多个下载任务，并利用CompletionService来管理这些异步任务的完成状态。每个下载任务作为一个独立的Callable对象被执行，完成后会返回一个整数标识文件编号。

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package com.shop;

import java.util.concurrent.*;
import java.util.*;

/**
 * @author liuyong 2012-3-22
 */
public class App {

    private static final ExecutorService   NEW_FIXED_THREAD_POOL = Executors.newFixedThreadPool(10);
        private static CompletionService<Integer> completionService     = new ExecutorCompletionService<Integer>(
                                                                         NEW_FIXED_THREAD_POOL);


	public static void main(String[] args) {
        for (int i = 0; i < 10; i++) {
            DownLoader<Integer> downLoader = new DownLoader<Integer>();
            downLoader.setIndex(i);
            completionService.submit(downLoader);
        }
        for (int i = 0; i < 10; i++) {
            try {
                Future<Integer> future = completionService.take();
                Integer str = future.get();
                System.out.println("take file [" + str + "];" + "time ["
                                   + new Date() + "];");
            } catch (InterruptedException e) {
                break;
            } catch (ExecutionException e) {
                break;
            }
        }
        NEW_FIXED_THREAD_POOL.shutdown();
        System.out.println("ok");
	}

    private static class DownLoader<Integer> implements Callable<Integer> {

        private Integer index;

        public void setIndex(Integer index) {
            this.index = index;
        }

        public Integer call() throws Exception {
            try {
                Random random = new Random();
                Thread.sleep(random.nextInt(20) * 1000);
            } catch (InterruptedException e) {
                System.out.println(e);
            }
            return index;
        }
    }
}