使用Jackson / Gson Java进行JSON解析

Question

I have the following Json

{
   "messages":[
      {
         "message":{
            "body":"Foo",
            "username":"XYZ"
         }
      },
      {
         "message":{
            "body":"HI",
            "username":"ABC"
         }
      }
   ],
   "response":{
      "status":200
   },
   "more":true
}

I build Custom classes My container class Result holds a List objects a Response object which contains a status and a boolean.

public class Message { 

  @SerializedName("body") 
  public String body; 

  @SerializedName("username") 
  public String username; 

  @Override public String toString() { 
    return "Message{" + "body=" + body + ", username=" + username + '}'; 
  } 
}

public class Response { 
  public int status; 
} 

public class SearchResponseST { 
  @SerializedName("messages") 
  public Message[] messages; 
  public Response response; 
  public boolean more;
}

In my main class I do:

SearchResponseST response = 
   gson.fromJson(reader, SearchResponseST.class); Message[] results = response.messages; 

If I eliminate the "message": and start the array directly, I am able to deserialize successfully using Gson.

How should I be parsing it with the current structure?

Answer 1

Though this does not answer your question directly, because I do not use Gson. I have always used the org.json.simple package to parse JSSON. you can read about it here: http://www.mkyong.com/java/json-simple-example-read-and-write-json/ Just throw the JSON into the parser, and get the data you want out. Data is accessed just like you would access a HashMap (for JSONObject) or ArrayList (for JSONArray).

EDIT with parsing code:

    JSONParser parser = new JSONParser();
    JSONObject obj = (JSONObject) parser.parse(new FileReader("file.txt"));
    JSONArray array = (JSONArray) obj.get("messages");
    for (Object o : array) {
      JSONObject jo =(JSONObject)o;
      JSONObject messageObject = (JSONObject)jo.get("message");
      System.out.println(messageObject.get("body"));
      System.out.println(messageObject.get("username"));
    }

Answer 2

For a JSON like this

 {
       "messages":
        [
          {"body": "Foo", "username": "XYZ"   },
          {"body": "HI",  "username": "ABC"  }

        ],
        "response": {"status": 200 },
        "more": true
    }

try Container object designed like

Container { List<Message> messages;Response response;boolean more;}

BUT for the JSON you have posted, the Container object should be

Container { public HashMap[] messages;  public boolean more;    public Response response; }