Retrieving Java Objects from a json post request

Question

I am developing a restful web application using java and jax-rs. In server side, I have to accept Json type requests as given by the client using POST method.

@POST
@Path("/Request")
@Consumes(MediaType.APPLICATION_JSON)
public String process(SMessage message) throws Exception  {
         message.getHeader();
         message.getBody();
}

The json object have two composite fields like in the below format.

{
  "header": {
    "serviceType": "A"
  },
  "body": {
    "id": "1",
    "name": "abc"
  }
}

Based on the serviceType specified in the Header field, the parameters in the body will differ. I need to map this body field in to a java POJO class. The POJO class is not the same for all requests. How can I achieve this effectively?

Answer 1

If you are using Jackson as your JSON parser, a simple way is to declare body to be a JsonNode to handle dynamic keys as follows:

class MyResponse {
    private MyHeader header;
    private JsonNode body;

    //general getters and setters
}

And I assumed that you have already a POJO for header such as:

class MyHeader {
    private String serviceType;

    //general getters and setters
}

Finally, let's verify that it works:

String responseStr = "{\"header\": {\"serviceType\": \"A\"},\"body\": {\"id\": \"1\",\"name\": \"abc\"}}";

ObjectMapper mapper = new ObjectMapper();
MyResponse myResponse = mapper.readValue(responseStr, MyResponse.class);
System.out.println(myResponse.getBody().get("name").asText());

Console output:

abc

Another way to solve this issue is by using Map and everything else is the same:

class MyResponse {
    private MyHeader header;
    private Map<String, Object> body;

    //general getters and setters
}