使用restTemplate发送post请求，传入参数是在requestBody请求体中，以json形式传输

@PostMapping
    public ResponseResult add(User user){
        HttpHeaders httpHeaders = new HttpHeaders();
        MediaType type=MediaType.parseMediaType("application/json;charset=UTF-8");
        httpHeaders.setContentType(type);

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

        HashMap<String, Object> map = new HashMap<>();
        map.put("userName",user.getUserName());
        map.put("passWord",user.getPassWord());
        HttpEntity<Map<String, Object>> objectHttpEntity = new HttpEntity<>(map,httpHeaders);
        ResponseEntity<ResponseResult> responseResultResponseEntity = restTemplate.postForEntity(GLOBAL_URL, objectHttpEntity, ResponseResult.class);
        return responseResultResponseEntity.getBody();

特别注意，当没有请求头信息时，用  MultiValueMap<String, Object> map=new LinkedMultiValueMap<>();

当有请求头信息时，用 HashMap<String, Object> map = new HashMap<>();