1.下载commons-io-2.2.jar，放进项目中

public class LianXiThread extends Thread{private String url;private String name;//定义构造方法public LianXiThread(String url, String name){this.url = url;this.name = name;}//重写run()方法@Overridepublic void run() {//new 出一个WebDownloader 对象WebDownloader webDownloader = new WebDownloader();//调用下载方法webDownloader.downloader(url, name);System.out.println("下载了名为：" + name);}public static void main(String[] args) {LianXiThread t1 = new LianXiThread("http://img.keaitupian.cn/newupload/08/1629793828632844.jpg", "1.jpg");LianXiThread t2 = new LianXiThread("http://img.keaitupian.cn/newupload/08/1629793443133324.jpg", "2.jpg");LianXiThread t3 = new LianXiThread("http://img.keaitupian.cn/newupload/08/1629792944161959.jpg", "3.jpg");t1.start();t2.start();t3.start();}//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 (Exception e){e.printStackTrace();System.out.println("IO异常,downloader出现问题");}}}
}

下载成功