making a GSON request using volley

Question

I have the following json response

{
  \"tag\": [
    {
      \"listing_count\": 5,
      \"listings\": [
        {
          \"source\": \"source1\",
               


        

Answer 1

I just made a custom json request which is based on Jackson library instead of Gson.

One thing I want to point out (it took my many hours to figure out...): if you want to support POST Json parameter as well, you should extend from JsonRequest instead of Request. Otherwise your Json request body will be url-encoded, on the server side you cannot convert it back to java object.

Here is my json request class, which is based on Jackson and supports Json parameter and header:

    public class JacksonRequest extends JsonRequest {

    private final ObjectMapper objectMapper = new ObjectMapper();
    private final Class responseClass;
    private final Map headers;

    private String requestBody = null;
    private static final String PROTOCOL_CHARSET = "utf-8";

    /**
     * POST method without header
     */
    public JacksonRequest(String url,
                          Object parameterObject,
                          Class responseClass,
                          Response.Listener listener,
                          Response.ErrorListener errorListener) {

        this(Method.POST, url, null, parameterObject, responseClass, listener, errorListener);
    }

    /**
     * @param method see also com.android.volley.Request.Method
     */
    public JacksonRequest(int method,
                          String url,
                          Map headers,
                          Object parameterObject,
                          Class responseClass,
                          Response.Listener listener,
                          Response.ErrorListener errorListener) {

        super(method, url, null, listener, errorListener);

        if (parameterObject != null)
            try {
                this.requestBody = objectMapper.writeValueAsString(parameterObject);
            } catch (JsonProcessingException e) {
                e.printStackTrace();
            }

        this.headers = headers;
        this.responseClass = responseClass;
    }

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

    @Override
    protected Response parseNetworkResponse(NetworkResponse response) {
        try {
            String json = new String(response.data, HttpHeaderParser.parseCharset(response.headers));
            ResponseType result = objectMapper.readValue(json, responseClass);
            return Response.success(result, HttpHeaderParser.parseCacheHeaders(response));

        } catch (UnsupportedEncodingException e) {
            return Response.error(new ParseError(e));
        } catch (JsonMappingException e) {
            return Response.error(new ParseError(e));
        } catch (JsonParseException e) {
            return Response.error(new ParseError(e));
        } catch (IOException e) {
            return Response.error(new ParseError(e));
        }
    }

    /**
     * Cannot call objectMapper.writeValueAsString() before super constructor, so override the same getBody() here.
     */
    @Override
    public byte[] getBody() {
        try {
            return requestBody == null ? null : requestBody.getBytes(PROTOCOL_CHARSET);
        } catch (UnsupportedEncodingException uee) {
            VolleyLog.wtf("Unsupported Encoding while trying to get the bytes of %s using %s",
                    requestBody, PROTOCOL_CHARSET);
            return null;
        }
    }

}