获取远程文件下载

    //获取远程文件下载
    private static void toDownload(String filePath , HttpServletResponse response) {
        ServletOutputStream out = null;
        InputStream inputStream = null;
        try {
            //路径
            // 取得文件的后缀名。
            String ext = filePath.substring(filePath.lastIndexOf(".") + 1).toLowerCase();
            //文件名
            String pdfName = System.currentTimeMillis() + "." + ext;
            // 获取外部文件流
            URL url = new URL(filePath);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            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)");
            inputStream = conn.getInputStream();
            /**
             * 输出文件到浏览器
             */
            int len = 0;
            // 输出 下载的响应头，如果下载的文件是中文名，文件名需要经过url编码
            response.setContentType("application/x-download");
            response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(pdfName, "UTF-8"));
            response.setHeader("Cache-Control", "no-cache");
            out = response.getOutputStream();
            byte[] buffer = new byte[1024];
            while ((len = inputStream.read(buffer)) > 0) {
                out.write(buffer, 0, len);
            }
            out.flush();
        } catch (Exception e) {

            e.printStackTrace();
        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (Exception e) {
                }
            }
            if (out != null) {
                try {
                    out.close();
                } catch (Exception e) {
                }
            }
        }
    }