Async task's messages exchange with Java Servlet

Question

I have a simple app communicating with its Servlet backend through an Async task. I have some trouble understanding how the messages are wrapped up and how to manipulate th

Answer 1

Set the servlet's content type to application/json and return a JSON string (e.g using Gson or Jackson to serialize the result.

On the Android side you can deserialize the JSON string, either using Android's built-in JSON classes or (better) using the same libraries you used in your servlet.

For example, if Tour is something like:

public class Tour {
  // some simple int/string/list fields
}

You can build a response class like:

public class Tours {
  private List<Tour> tours;
  // ...
}

Then on the server side (see this question, I'm using Gson here):

List<Tour> listOfTours = ...;
Tours tours = new Tours(listOfTours);
response.setContentType("application/json");
PrintWriter out = response.getWriter();
out.print((new Gson()).toJson(tours));
out.flush();

And on the client side:

String jsonResponse = ...;
Tours tours = (new Gson()).fromJson(jsonResponse, Tours.class);

There are some optimizations to be made, but that could get you started. Also, consider using OkHttp for your HTTP connections instead of using HttpClient, you'll probably end up with simpler and more robust code.