servlet-response-download

 1         //1.获取下载文件的路径
        String filePath = "D:\\projects\\servlet-project\\servlet-response-download\\target\\classes\\img\\111.jpg";
        //2.获取文件名
        String fileName = filePath.substring(filePath.lastIndexOf("\\") + 1);
        //3、设置header
        resp.setHeader("Content-Disposition", "attachment;filename="+ URLEncoder.encode(fileName,"utf-8"));
        //4、设置下载文件的输入流
        FileInputStream inputStream = new FileInputStream(filePath);
        //5、创建缓冲区
        int len = 0;
        byte[] buff = new byte[1024];
        //6、获取输出流
        ServletOutputStream outputStream = resp.getOutputStream();
        while ((len=inputStream.read(buff))>0) {
            outputStream.write(buff,0,len);
        }
        inputStream.close();
        outputStream.close();22     }
####URL

　　URL url = new URL("https://WWW.BAIDU.COM"); 
　　URLConnection conn = url.openConnection();         

　　resp.setHeader("Content-Disposition", "attachment;filename="+ URLEncoder.encode("163.html","utf-8"));

　　InputStream is = conn.getInputStream();
　　ServletOutputStream os = resp.getOutputStream();

　　int len = 0;
　　byte[] buff = new byte[1024];
　　while ((len=is.read(buff))>0) {
    　　os.write(buff,0,len);
　　}
　　is.close();
　　os.close();