URL ur = new URL("http://localhost:8080/first/he.txt"); HttpURLConnection conn = (HttpURLConnection) ur.openConnection();//URL.openConnection() -- >return URLCommection(直接子类HttpURLConnection) conn.setRequestProperty("Range", "bytes=5-");//设置请求参数属性，设置下载从第5个字节开始下载； InputStream in = conn.getInputStream(); int len = 0; byte[] buf = new byte[1024]; FileOutputStream out = new FileOutputStream("d:\\a.txt"); while ((len = in.read(buf)) > 0) { out.write(buf, 0, len); } in.close(); out.close();