web service response json serialized List

Question

i'm trying to transfer a list of objects from a server to a client using a web service. The data should be transfered in json format. I'm using jersey for the JAX-RS implementation and gson to deserialise the json string on the client side. I kept getting a parse error, even though i was using the recommended practice for list deserilization with gson (see below). I have found out that the json string which i am getting in the response is different than the one which i should receive in order for the gson deserilizer to work.

This is the reponse i'm getting from the web service:

{"activity":[{"activityName":"c","id":"3"},{"activityName":"c","id":"3"},{"activityName":"c","id":"3"}]}

But this is the correct response i should receive in order for the gson to deserialize the string to a List: [{"id":3,"activityName":"c"},{"id":3,"activityName":"c"},{"id":3,"activityName":"c"}]

You can see the added header/wrapper "activity" in the begining of the first string.

Here is the web service code:

@Path("ws")
public class IiwsServices {

@POST
@Path("/listActivities")
@Produces(MediaType.APPLICATION_JSON)
public List<Activity> listActivities() {

    List<Activity> list = new ArrayList<Activity>();

    Activity act = new Activity();
    act.setId(1);
    act.setActivityName("a");
    list.add(act);

    act.setId(2);
    act.setActivityName("b");
    list.add(act);

    act.setId(3);
    act.setActivityName("c");
    list.add(act);
    return list;
}

This is the client code:

public class Main {
public static void main(String[] args) {
    try {

        Client client = Client.create();

        WebResource webResource = client
           .resource("http://localhost:8080/iiws.ws.test/ws/listActivities");

        ClientResponse response = webResource.accept(MediaType.APPLICATION_JSON)
                   .post(ClientResponse.class);

        if (response.getStatus() != 200) {
           throw new RuntimeException("Failed : HTTP error code : "
            + response.getStatus());
        }

        String output = response.getEntity(String.class);

        System.out.println(output);

        List<Activity> list = new ArrayList<Activity>();

        Activity act = new Activity();
        act.setId(1);
        act.setActivityName("a");
        list.add(act);

        act.setId(2);
        act.setActivityName("b");
        list.add(act);

        act.setId(3);
        act.setActivityName("c");
        list.add(act);

        Gson gson = new GsonBuilder().create();
        String jsonString = gson.toJson(list);

        System.out.println(jsonString);

        List<Activity> list = gson.fromJson(output, new   TypeToken<List<Activity>>(){}.getType()); // <-- Deserialize exception here

        for (int i = 0; i < list.size(); i++) {
            Activity x = list.get(i);
            System.out.println(x);
        }

      } catch (Exception e) {

        e.printStackTrace();

      }

}

****OK I believe I have found the answer****

OK finally found solution Here i found a similar question after googling for jersey and jackson : Jersey client can not deserializable json services

And this helps as well: JSON POJO support

Button line is that if not explicitely defined in the web.xml, jersey+jaxb is used instead of jersey+jackson

score 0 · Answer 1 · answered May 17 '13 at 12:06

from json string that the web server return, its clear that the response have an object that name is activity which has an array of activity.

so if you try this structure to read the response.


    public class Activity{
        private int id;
        private String activityName;
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getActivityName() {
            return activityName;
        }
        public void setActivityName(String activityName) {
            this.activityName = activityName;
        }
   }

    public class Response{
        private List activity;

        public List getActivity() {
            return activity;
        }

        public void setActivity(List activity) {
            this.activity = activity;
        }

    }

and to read it using gson Library


    Gson gson = new Gson();
    Response response  = gson.fromJson(json, Response.class);

1 Answers1