GsonRequest.java

// from https://gist.github.com/ficusk/5474673

package com.commonsware.android.volley;

import com.google.gson.Gson;
import com.google.gson.JsonSyntaxException;

import com.android.volley.AuthFailureError;
import com.android.volley.NetworkResponse;
import com.android.volley.ParseError;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.Response.ErrorListener;
import com.android.volley.Response.Listener;
import com.android.volley.toolbox.HttpHeaderParser;

import java.io.UnsupportedEncodingException;
import java.util.Map;

/**
 * Volley adapter for JSON requests that will be parsed into Java objects by Gson.
 */
public class GsonRequest<T> extends Request<T> {
  private final Gson gson = new Gson();
  private final Class<T> clazz;
  private final Map<String, String> headers;
  private final Listener<T> listener;

  /**
   * Make a GET request and return a parsed object from JSON.
   *
   * @param url URL of the request to make
   * @param clazz Relevant class object, for Gson's reflection
   * @param headers Map of request headers
   */
  public GsonRequest(String url, Class<T> clazz, Map<String, String> headers,
                     Listener<T> listener, ErrorListener errorListener) {
    super(Method.GET, url, errorListener);
    this.clazz = clazz;
    this.headers = headers;
    this.listener = listener;
  }

  @Override
  public Map<String, String> getHeaders() throws AuthFailureError {
    return headers != null ? headers : super.getHeaders();
  }

  @Override
  protected void deliverResponse(T response) {
    listener.onResponse(response);
  }

  @Override
  protected Response<T> parseNetworkResponse(NetworkResponse response) {
    try {
      String json = new String(
        response.data, HttpHeaderParser.parseCharset(response.headers));
      return Response.success(
        gson.fromJson(json, clazz), HttpHeaderParser.parseCacheHeaders(response));
    } catch (UnsupportedEncodingException e) {
      return Response.error(new ParseError(e));
    } catch (JsonSyntaxException e) {
      return Response.error(new ParseError(e));
    }
  }
}