java 调用浏览器下载网络文件

最新推荐文章于 2024-07-18 10:59:44 发布

原创最新推荐文章于 2024-07-18 10:59:44 发布 · 3.8k 阅读

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#java #upload #file

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本文介绍了一个文件下载API的具体实现过程，包括如何通过HTTP请求获取指定ID的文件，并将其发送给客户端。文章详细展示了如何处理文件路径、文件名编码、设置响应头及处理各种异常情况。

/**
     * 文件下载
     * @param response
     * @param fileId 文件Id
     * @throws UnsupportedEncodingException
     */
    @ResponseBody
    @RequestMapping(value = "/exportUI")
    public void exportUI(HttpServletResponse response, HttpServletRequest request, Long fileId) throws UnsupportedEncodingException, MalformedURLException {
        if (fileId != null){
            TbStFj tbStFj = fjService.selectByPrimaryKey(fileId);
            if (tbStFj != null){
                String path = serviceAddress + tbStFj.getFjdz();
                String fileName = tbStFj.getFjmc();
                response.reset();
                response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(fileName, "UTF-8"));
                response.setHeader("Connection", "close");
                response.setHeader("Content-Type", "application/octet-stream");
                response.setHeader("Access-Control-Allow-Origin", "*");
                response.setContentType("application/OCTET-STREAM");
                try
                {
                    URL url = new URL(path);
                    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 {
                        ServletOutputStream out = response.getOutputStream();
                        request.setCharacterEncoding("UTF-8");
                        int BUFFER = 1024*10;
                        byte data[] = new byte[BUFFER];
                        BufferedInputStream bis = null;
                        //获取文件输入流
                        InputStream fis = conn.getInputStream();
                        int read;
                        bis = new BufferedInputStream(fis,BUFFER);
                        while((read = bis.read(data)) != -1){
                            out.write(data, 0, read);
                        }
                        fis.close();
                        bis.close();
                    } catch (IOException e) {
                        logger.error("文件下载异常", fileName, e.fillInStackTrace());
                    }
                } catch (Exception e)
                {
                    e.printStackTrace();
                    System.out.println("抛出异常！！");
                }

            }

        }
    }