多线程之实现Callable接口完成同步下载文件

导入依赖

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.7</version>
</dependency>

创建Thread1 类 实现多线程下载文件

public class Thread1 implements Callable<Boolean> {
    //网络地址
    private String url;
    //保存的文件名
    private String name;
    public Thread1(String url, String name) {
        this.url = url;
        this.name = name;
    }
    //下载文件的线程执行体
    @Override
    public Boolean call() {
        FileDownLoader fileDownLoader = new FileDownLoader();
        fileDownLoader.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 {
        Thread1 t1 = new Thread1("https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=1887333225,3220403259&fm=26&gp=0.jpg","紫霞仙子.jpg");
        Thread1 t2 = new Thread1("https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=1115306696,372850764&fm=26&gp=0.jpg","冰霜恋舞曲.jpg");
        Thread1 t3 = new Thread1("https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=3005655293,1504161907&fm=26&gp=0.jpg","元素使.jpg");
        //创建执行服务
        ExecutorService service = Executors.newFixedThreadPool(3);
        //提交执行
        Future<Boolean> f1 = service.submit(t1);
        Future<Boolean> f2 = service.submit(t2);
        Future<Boolean> f3 = service.submit(t3);
        //获取结果
        Boolean rs1 = f1.get();
        Boolean rs2 = f2.get();
        Boolean rs3 = f3.get();
        //关闭服务
        service.shutdown();
    }
}

//下载器
class FileDownLoader{
    // 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方法出错");
        }
    }
}

Callable的的优点：

• 可以自定义返回值
• 可以抛出异常