如何将 JSON 对象发布到 spring 控制器?

我有弹簧控制器:

@RequestMapping(value = "/add", method = RequestMethod.POST, 
     consumes = "application/json")
public @ResponseBody ResponseDto<Job> add(User user) {
    ...
}

我可以像这样使用 APACHE HTTP CLIENT 发布对象:

I can POST the object like this with APACHE HTTP CLIENT:

HttpPost post = new HttpPost(url);
List nameValuePairs = new ArrayList();
nameValuePairs.add(new BasicNameValuePair("name", "xxx"));
post.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = client.execute(post);

在控制器中，我得到名为xxx"的用户

In controller I get user with name "xxx"

现在我想创建 User 对象并将其发布到服务器，我试图像这样使用 GSON 对象:

Now I want to create User object and post it to the server, I tried to use with GSON object like this :

User user = new User();
user.setName("yyy");

Gson gson = new Gson();
String json = gson.toJson(user);

HttpClient client = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
StringEntity entity = new StringEntity(json.toString(), HTTP.UTF_8);
entity.setContentType("application/json");
httpPost.setEntity(entity);
HttpResponse response = client.execute(httpPost);

但是通过这种方式，我进入了带有空字段的服务器用户对象...

But in this way I get in server User object with null fields...

我该如何解决?