原因为没有指定请求头contentType，需要在代码中指定一下

原代码：

接口报错：Content type 'application/xml;charset=UTF-8' not supported

    @Autowired
    private RestTemplate restTemplate;


    Map<String,Object> params = new HashMap<>();
    params.put("gender","gender");
    params.put("age",""age);
    params.put("city","city");

    String url = "http://wit-user/v1/userList";

    Respose<List<User>> response = restTemplate.postForObject(url, parsms, Response.class);

修改后：

正确返回数据

    @Autowired
    private RestTemplate restTemplate;


    Map<String,Object> params = new HashMap<>();
    params.put("gender","gender");
    params.put("age",""age);
    params.put("city","city");

    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.APPLICATION_JSON_UTF8);
    headers.set("Accept", "application/json");
    HttpEntity httpEntity = new HttpEntity<>(params, headers);

    String url = "http://wit-user/v1/userList";

    Respose<List<User>> response = restTemplate.postForObject(url, httpEntity, Response.class);