RestTemplate发送MultipartFile

@Override
public void transmit(MultipartFile file) {
    // 临时文件保存路径
    File fileTemp = FileUtil.mkdir(System.getProperty("user.dir") + "\\temp" + "\\" + file.getOriginalFilename());
    // 转存文件
    try {
        file.transferTo(fileTemp);
    } catch (IOException e) {
        e.printStackTrace();
    }
    HttpHeaders headers = new HttpHeaders();
    //设置提交方式都是表单提交
    headers.setContentType(MediaType.MULTIPART_FORM_DATA);
    //设置表单信息
    MultiValueMap<String, Object> params = new LinkedMultiValueMap<>();
    params.add("file", new FileSystemResource(fileTemp));
    HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<>(params, headers);
    restTemplate.postForEntity(
        "http://xxx:xx/xxxxx",requestEntity, String.class);
    FileUtil.del(fileTemp);
}