Gson整合Volley返回对象--GsonRequest

Gson是一个使用映射支持JSON与Java对象之间相互转换的库文件。你可以定义和JSON keys相对应名称的Java对象。把对象传递给传递Gson，然后Gson会帮你为对象填充字段值。 下面是一个完整的示例：演示了使用Gson解析Volley数据：

 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));
         }
     }
 }