Java实现Callable接口

实现Callable接口

1. 实现Callable接口，需要返回值类型
2. 重写call方法，需要抛出异常
3. 创建目标对象
4. 创建执行服务：ExecutorService ser = Executors.newFixedThreadPool(1);
5. 提交执行：Future result1 = ser.submit(t1);
6. 获取结果：boolean r1 = result1.get()
7. 关闭服务：ser.shutdowmNow();

package com.xiao.demo01;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.concurrent.*;

//线程创建方式三，实现Callable接口
/*
callable的好处
1.可以定义返回值
2.可以抛出异常。
 */

public class TestCallable implements Callable<Boolean> {

    private String url; //网络图片地址
    private String name; //保存的文件名

    public TestCallable(String url, String name) {
        this.url = url;
        this.name = name;
    }

    //下载图片线程的执行体
    @Override
    public Boolean call() {
        WebDownloader webDownloader = new WebDownloader();
        webDownloader.downloader(url, name);
        System.out.println("下载了文件名为" + name);
        return true;
    }

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        TestCallable testThread1 = new TestCallable("https://img2020.cnblogs.com/blog/35695/202102/35695-20210228140227933-2125906102.jpg", "2.jpg");
        TestCallable testThread2 = new TestCallable("https://img2020.cnblogs.com/blog/35695/202102/35695-20210228140227933-2125906102.jpg", "2.jpg");
        TestCallable testThread3 = new TestCallable("https://img2020.cnblogs.com/blog/35695/202102/35695-20210228140227933-2125906102.jpg", "2.jpg");

        //创建执行服务：
        ExecutorService ser = Executors.newFixedThreadPool(3);

        //提交执行
        Future<Boolean> r1 = ser.submit(testThread1);
        Future<Boolean> r2 = ser.submit(testThread2);
        Future<Boolean> r3 = ser.submit(testThread3);

        //获取圣果
        boolean rs1 = r1.get();
        boolean rs2 = r2.get();
        boolean rs3 = r3.get();

        System.out.println(rs1);
        System.out.println(rs2);
        System.out.println(rs3);

        //关闭服务
        ser.shutdownNow();


    }


    //下载方法
    public void downloader(String url, String name) {
        try {
            try {
                FileUtils.copyURLToFile(new URL(url), new File(name));
            } catch (IOException e) {
                e.printStackTrace();
                System.out.println("IO异常，downloader方法出现问题");
            }
        } finally {

        }
    }
}

实现Callable接口创建线程