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.shutdownNow();

package com.wang.multiThread.demo02;

import com.wang.multiThread.demo01.TestThread2;
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 {
    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 t1 = new TestCallable("https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fimg12.360buyimg.com%2Fn2%2Fjfs%2Ft16657%2F184%2F2048108479%2F409928%2Fa7f806cf%2F5ae2ce54Ncdcf8bcd.jpg&refer=http%3A%2F%2Fimg12.360buyimg.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1646466401&t=0bcc5a77aa3cefd8335e4395ba59c753", "1.jpg");
        TestCallable t2 = new TestCallable("https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fimg12.360buyimg.com%2Fn2%2Fjfs%2Ft16657%2F184%2F2048108479%2F409928%2Fa7f806cf%2F5ae2ce54Ncdcf8bcd.jpg&refer=http%3A%2F%2Fimg12.360buyimg.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1646466401&t=0bcc5a77aa3cefd8335e4395ba59c753", "2.jpg");
        TestCallable t3 = new TestCallable("https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fimg12.360buyimg.com%2Fn2%2Fjfs%2Ft16657%2F184%2F2048108479%2F409928%2Fa7f806cf%2F5ae2ce54Ncdcf8bcd.jpg&refer=http%3A%2F%2Fimg12.360buyimg.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1646466401&t=0bcc5a77aa3cefd8335e4395ba59c753", "3.jpg");

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

        //提交执行
        Future<Boolean> r1 = ser.submit(t1);
        Future<Boolean> r2 = ser.submit(t2);
        Future<Boolean> r3 = ser.submit(t3);

        //获取结果
        boolean rs1 = r1.get();
        boolean rs2 = r2.get();
        boolean rs3 = r3.get();

        //关闭服务
        ser.shutdownNow();
    }
}

//下载器
class WebDownloader {
    //下载方法
    public void downloader(String url, String name) {
        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");
        }
    }
}