实现Callable接口(了解即可)

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<Boolean> result1= ser.submit(t1);

6.获取结果:boolean r1 = result1.get()

7.关闭服务:ser.shutdownNow();

利用callable改造下载图片案例：

//线程创建方法三：实现Callable接口
public class TestCallable implements Callable<Boolean> {private String url;//网络图片地址private String name;//保存文件名public TestCallable(String url, String name){this.url = url;this.name =name;}//下载图片线程的执行体@Overridepublic Boolean call() {WeDownloader weDownloader = new WeDownloader();weDownloader.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://i-blog.csdnimg.cn/direct/71122db47a024d05b50daedfac6221d4.png", "4.png");TestCallable t2 = new TestCallable("https://i-blog.csdnimg.cn/img_convert/aa841f7c7d7d281d1d012d9a06a31d53.jpeg", "5.jpeg");TestCallable t3 = new TestCallable("https://i-blog.csdnimg.cn/direct/0e2270afec474c88bcb7e5d721c79011.jpeg", "6.jpeg");//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();}
}class WeDownloader{//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");}}}