从 JSON 对象实例化一个类

Question

I have a NodeJS WebSocket server in which I am required to create a Java client application for, however I haven't used JSON with Java in the past and I'm having some problems understanding how to create a class instance for the correct packet based on the type value in the Json object.

To give you a little more insight, we have the Packet class which is abstract and then subclasses such as AuthenticationPacket . We have a Map<> that stores the Classes as such, Map<String, Class> So an example entry would be ("Authentication success", AuthenticationPacket.class)

Here's an example of the JSON data that we get back from the server.

{
    "type": "Authentication success",
    "data": 
    {
        "username": "Hobbyist",
        "accountStatus": "USER"
    }
}

So my question is how would I create an new Class from the variables in the data field of the JSON response without having to pass in each parameter one at a time based on the type with a new AuthenticationPacket(...)

Is there any way to do some sort of linking between the JSON and the class where it just creates a new instance of the class with all of the variables present in the data ?

Thanks

Answer 1

I hope i didn't get you wrong.

if you can convert json string to JSONObject ( I am using vert.x JsonObject )

PacketSErvice handles all Requests

 public class PacketService {

    private static PacketService instance; 

        private PacketService(){}
        public static PacketService newInstance(){

            if(instance == null) {
                instance = new PacketService();
            }
            return instance; 
        }

        public <T extends Packet> T handlePacket(Class<T> clazz, JSONObject data){
            return (T) clazz.newInstance().fromJson(data);
        }

      }

Packet interface

 public interface Packet {  

            Packet fromJson(JSONObject object); 

            JSONObject asJson();

        }

And implement to your requests if you will have classes XPacket , YPacket , ZPacket

Xpacket packet = PacketService.newInstance().handlePacket(XPacket.class,jsonData);