java实现文件下载功能，自动弹出保存窗口

最新推荐文章于 2024-07-18 10:59:44 发布

ntotl

最新推荐文章于 2024-07-18 10:59:44 发布

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本文链接：https://blog.youkuaiyun.com/ntotl/article/details/49513067

本文介绍了一个HTTP请求处理方法，用于从指定URL下载文件，并通过HTTP响应将文件以流的形式发送给客户端。

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@RequestMapping(value="downLoadFromUrl")
    public void downLoadFromUrl(HttpServletRequest request,HttpServletResponse response,String downloadUrl,String ip,String longitude,String latitude) throws IOException{
        URL url = new URL(downloadUrl);
        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
                //设置超时间为3秒
        conn.setConnectTimeout(3*1000);
        //防止屏蔽程序抓取而返回403错误
        conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
        //得到输入流
        InputStream inputStream = conn.getInputStream();
        try {
            String fileName = "aaa.jpg";
            fileName = new String(fileName.getBytes("UTF-8"),"ISO8859-1");
            response.setContentType("application/octet-stream");
            response.addHeader("Content-Disposition", "attachment;filename="+fileName);
            String len = String.valueOf(inputStream.available()/1000+"k");
            response.setHeader("Content-Length", len);
            OutputStream out = response.getOutputStream();
            byte[] getData = readInputStream(inputStream);
            out.write(getData);
            inputStream.close();
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    /**
     * 从输入流中获取字节数组
     * @param inputStream
     * @return
     * @throws IOException
     */
    public static byte[] readInputStream(InputStream inputStream) throws IOException {
        byte[] buffer = new byte[1024];
        int len = 0;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        while((len = inputStream.read(buffer)) != -1) {
            bos.write(buffer, 0, len);
        }
        bos.close();
        return bos.toByteArray();
    }