url转变为 MultipartFile对象

/**
 * url转变为 MultipartFile对象
 * @param url
 * @param fileName
 * @return
 * @throws Exception
 */
private static MultipartFile createFileItem(String url, String fileName) throws Exception{
    FileItem item = null;
    try {
        HttpURLConnection conn = (HttpURLConnection) new URL(url).openConnection();
        conn.setReadTimeout(30000);
        conn.setConnectTimeout(30000);
        //设置应用程序要从网络连接读取数据
        conn.setDoInput(true);
        conn.setRequestMethod("GET");
        if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
            InputStream is = conn.getInputStream();

            FileItemFactory factory = new DiskFileItemFactory(16, null);
            String textFieldName = "uploadfile";
            item = factory.createItem(textFieldName, ContentType.APPLICATION_OCTET_STREAM.toString(), false, fileName);
            OutputStream os = item.getOutputStream();

            int bytesRead = 0;
            byte[] buffer = new byte[8192];
            while ((bytesRead = is.read(buffer, 0, 8192)) != -1) {
                os.write(buffer, 0, bytesRead);
            }
            os.close();
            is.close();
        }
    } catch (IOException e) {
        throw new RuntimeException("文件下载失败", e);
    }

    return new CommonsMultipartFile(item);
}