GsonRequest.java

package com.prashant.adesara.volleysample.toolbox;

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

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.VolleyLog;
import com.android.volley.toolbox.HttpHeaderParser;
import com.google.gson.Gson;
import com.google.gson.JsonSyntaxException;

public class GsonRequest<T> extends Request<T>{

    /** Charset for request. */
    private static final String PROTOCOL_CHARSET = "utf-8";

    /** Content type for request. */
    private static final String PROTOCOL_CONTENT_TYPE =
        String.format("application/json; charset=%s", PROTOCOL_CHARSET);

    private final Listener<T> mListener;

    private final String mRequestBody;
    
    private Gson mGson;
    private Class<T> mJavaClass;
    
    public GsonRequest(int method, String url, Class<T> cls, String requestBody, Listener<T> listener,
            ErrorListener errorListener) {
        super(method, url, errorListener);
        mGson = new Gson();
        mJavaClass = cls;
        mListener = listener;
        mRequestBody = requestBody;
    }

    @Override
    protected void deliverResponse(T response) {
        mListener.onResponse(response);
    }
    
	private Map<String, String> headers = new HashMap<String, String>();
	
	@Override
	public Map<String, String> getHeaders() throws AuthFailureError {
		return headers;
	}
	
    @Override
    protected Response<T> parseNetworkResponse(NetworkResponse response) {
        try {
            String jsonString = new String(response.data, HttpHeaderParser.parseCharset(response.headers));
    		T parsedGSON = mGson.fromJson(jsonString, mJavaClass);
            return Response.success(parsedGSON,
                    HttpHeaderParser.parseCacheHeaders(response));
            
        } catch (UnsupportedEncodingException e) {
            return Response.error(new ParseError(e));
        } catch (JsonSyntaxException je) {
            return Response.error(new ParseError(je));
        }
    }

    @Override
    public String getBodyContentType() {
        return PROTOCOL_CONTENT_TYPE;
    }

    @Override
    public byte[] getBody() {
        try {
            return mRequestBody == null ? null : mRequestBody.getBytes(PROTOCOL_CHARSET);
        } catch (UnsupportedEncodingException uee) {
            VolleyLog.wtf("Unsupported Encoding while trying to get the bytes of %s using %s",
                    mRequestBody, PROTOCOL_CHARSET);
            return null;
        }
    }

}