下载远程文件

import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

　　

    /**
     * 下载飞行资料夹
     *
     * @param fileName
     * @param response
     * @return
     */
    @RequestMapping(value = "/download", method = {RequestMethod.POST, RequestMethod.GET})
    @ResponseBody
    public Object onDownload(String fileName, HttpServletResponse response) {
        ResponseJson json = new ResponseJson();

        HttpURLConnection con = null;
        InputStream is = null;
        try {
            URL url = new URL(ServiceConstants.DOWNLOAD_URL_FLIGHT + fileName);    // 远程文件url，如：http://211.64.201.201/uploadfile/nyz.mp3 
            con = (HttpURLConnection) url.openConnection();
            
            response.setContentType("multipart/form-data");    // 自动识别下载文件格式
            response.setHeader("Content-Disposition", "attachment;fileName=" + fileName.substring(8, fileName.length())); // 文件名
            response.setHeader("Content-Length", con.getHeaderField("Content-Length")); // 文件大小

            is = con.getInputStream();
            byte[] b = new byte[1024];
            int len = 0;
            while ((len = is.read(b)) != -1) {
                response.getOutputStream().write(b, 0, len);    // 仅写入读取到的字符，区别于write(b)
            }
            response.getOutputStream().flush();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (con != null) {
                    con.disconnect();
                }
                if (is != null) {
                    is.close();
                }
                if (response.getOutputStream() != null) {
                    response.getOutputStream().close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        
        json.setSuccess(true);
        return json;
    }