将任何类型的文件从SFTP直接下载到浏览器

Question

我正在尝试使用Jsch库从SFTP下载文件（文件类型没有限制）。我正在使用spring-mvc来做同样的事情。我成功地将响应数据提供给我的AngularJS控制器。但是，下载的文件中没有任何内容。下面是我的AngularJS代码和弹簧控制器代码。

@RequestMapping(value = "/downloadAttachment", method = RequestMethod.POST,
            produces = MediaType.APPLICATION_OCTET_STREAM_VALUE)
public void downloadAttachment(
    @RequestParam(value = "fileName") String fileName,
    @RequestParam(value = "filePath") String filePath,
    @RequestParam(value = "fileId") String fileId,
    HttpServletResponse response, Locale locale) throws Exception {
InputStream is = null;
if(!fileName.isEmpty() && !filePath.isEmpty() && !fileId.isEmpty()){
    String directory = filePath;
    java.util.Properties config = new java.util.Properties();
    config.put("StrictHostKeyChecking", "no");
    JSch ssh = new JSch();
    Session session = ssh.getSession(sftpLogin, sftpAddress, 22);
    session.setConfig(config);
    session.setPassword(sftpPassword);
    session.connect();
    logger.info("Connection to server established");
    Channel channel = session.openChannel("sftp");
    channel.connect();

    ChannelSftp sftp = (ChannelSftp) channel;
    sftp.cd(directory);
    is = sftp.get(fileName);
   IOUtils.copy(is, response.getOutputStream());
   is.close();
   channel.disconnect();
   session.disconnect();
}

}

以下是我的AngularJS承诺函数。

function downloadAttachment(file){
    if(file!= null){
        var promise = myService.downloadAttachment(file);
        promise.then(function(downloadResponseData){
            if(downloadResponseData != null){

                var blob = new Blob([downloadResponseData], {type: 'application/octet-stream', disposition: 'attachment'});
                var objectUrl = URL.createObjectURL(blob);
                var a = document.createElement("a");
                document.body.appendChild(a);
                a.style = "display: none";
                a.href = objectUrl;
                a.download = row.entity._file.name;
                a.click();
            }
        }),function(errorPayload){

        }
    }
}

我无法在上面的代码中找到错误。 我只需要下载文件及其内容