Java多线程之FutureTask的介绍及使用

package com.xz.thread.FutureTask;

import java.util.concurrent.Callable;

/**
 * @description: 创建一个计算任务类，实现Callable接口,重写call方法
 * @author: xz
 * @create: 2021-06-02 22:06
 */
public class ComputeTask implements Callable<Integer> {

    private String taskName;//任务名称

    //任务构造器
    public ComputeTask(String taskName) {
        this.taskName = taskName;
        System.out.println("创建【计算任务】开始，计算任务名称：" + taskName);
    }

    //计算任务的方法
    @Override
    public Integer call() throws Exception {
        Integer result = 0;
        for (int i = 1; i <=50; i++) {
            result = +i;
        }
        System.out.println("【计算任务】"+taskName +"执行完成。");
        return result;
    }
}

package com.xz.thread.FutureTask;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.FutureTask;

/**
 * @description:
 * @author: xz
 * @create: 2021-06-01 22:44
 */
public class Demo {
    public static void main(String[] args) {
        //任务集合
        List<FutureTask<Integer>> futureTasks  = new ArrayList<>();
        //创建固定长度的线程池
        ExecutorService pool = Executors.newFixedThreadPool(5);
        for (int i = 1; i <= 10; i++) {
            //实例化FutureTask，传入计算任务类
            FutureTask<Integer> futureTask = new FutureTask<>(new ComputeTask(i + ""));
            //添加到任务集合中
            futureTasks.add(futureTask);
            //提交任务到线程池
            pool.submit(futureTask);
        }
        System.out.println("所有【计算任务】提交完毕，主线程开始执行");

        System.out.println("【主线程任务】开始============");
        //主线程睡眠5秒，模拟主线程做某些任务
        try {
            Thread.sleep(5000);
            System.out.println("【主线程任务】开始执行某些任务============");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("【主线程任务】结束============");

        //用于打印任务执行结果
        Integer result = 0;
        for (FutureTask<Integer> task : futureTasks) {
            try {
                //FutureTask的get()方法会自动阻塞，知道得到任务执行结果为止
                result += task.get();
            } catch (InterruptedException e) {
                e.printStackTrace();
            } catch (ExecutionException e) {
                e.printStackTrace();
            }
        }
        //关闭线程池
        pool.shutdown();
        System.out.println("多线程多任务执行结果：" + result);

    }

}