使用Spring Rest模板+ Spring Web MVC分段上传文件

Question

我正在尝试使用带有以下代码的RestTemplate上传文件。

   MultiValueMap<String, Object> multipartMap = new LinkedMultiValueMap<>();

   multipartMap.add("file", new ClassPathResource(file));

   HttpHeaders headers = new HttpHeaders();

   headers.setContentType(new MediaType("multipart", "form-data"));

   HttpEntity<MultiValueMap<String, Object>> request = new HttpEntity<MultiValueMap<String, Object>>(multipartMap, headers);

   System.out.println("Request for File Upload : " + request);

   ResponseEntity<byte[]> result = template.get().exchange(

                    contextPath.get() + path, HttpMethod.POST, request,

                    byte[].class);

我有MultipartResolverbean，控制器代码是

@RequestMapping(value = "/{id}/image", method = RequestMethod.POST)

@ResponseStatus(HttpStatus.NO_CONTENT)

@Transactional(rollbackFor = Exception.class)

public byte[] setImage(@PathVariable("id") Long userId,

        @RequestParam("file") MultipartFile file) throws IOException {

    // Upload logic

}

我得到以下异常

 org.springframework.web.bind.MissingServletRequestParameterException: Required MultipartFile parameter 'file' is not present

        at org.springframework.web.method.annotation.RequestParamMethodArgumentResolver.handleMissingValue(RequestParamMethodArgumentResolver.java:255) ~[spring-web-4.0.6.RELEASE.jar:4.0.6.RELEASE]

        at org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:95) ~[spring-web-4.0.6.RELEASE.jar:4.0.6.RELEASE]

        at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:79) ~[spring-web-4.0.6.RELEASE.jar:4.0.6.RELEASE]

        at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:157) [spring-web-4.0.6.RELEASE.jar:4.0.6.RELEASE]