Volley之自定義GsonRequest

第一步：導入volley 和gson的jar

第二步：<uses-permission android:name="android.permission.INTERNET" />

第三步： static 的單例類，用於管理volley中的方法

public class MySingleton {
          private static MySingleton mInstance;
          private static Context context;
          private RequestQueue mRequestQueue;
          public static synchronized MySingleton getInstance(Context context) {
                     if (mInstance == null) {
                               mInstance = new MySingleton(context);
                     }
                      return mInstance;
            }

           private MySingleton(Context mcontext) {
                   context = mcontext;
                    mRequestQueue = getRequestQueue();
           }

            public RequestQueue getRequestQueue() {
                      if (mRequestQueue == null) {// ApplicationContext確保volley的隊列在app運行中都存在
                      mRequestQueue = Volley.newRequestQueue(context.getApplicationContext());
                     }
                    return mRequestQueue;
              }

               public <T> void addToRequestQueue(Request<T> req) {
                     getRequestQueue().add(req);
                  }
}

第四步： 自定義Gson請求
public class GsonRequest<T> extends Request<T> {

             private final Listener<T> mListener;
             private Gson mGson;
             private Class<T> mClass;

            public GsonRequest(String url, Class<T> mClass, Listener<T> mListener,ErrorListener listener) {
                 this(Method.GET, url, mClass, mListener, listener);
             }

            public GsonRequest(int method, String url, Class<T> mClass,
                                       Listener<T> mListener, ErrorListener listener) {
                            super(method, url, listener);
                            mGson = new Gson();
                            this.mClass = mClass;
                            this.mListener = mListener;
           }

          @Override//將服務器響應的數據解析出來，而後Gson的fromJson方法將數據組裝成對象,在工做線程中運行
          protected Response<T> parseNetworkResponse(NetworkResponse response) {
                     try {
                                  String jsonString = new String(response.data,
                                  HttpHeaderParser.parseCharset(response.headers));
                                   return Response.success(mGson.fromJson(jsonString, mClass),
                                                            HttpHeaderParser.parseCacheHeaders(response));
                      } catch (UnsupportedEncodingException e) {
                                 return Response.error(new ParseError(e)); 
                      }
 
            }
            //最終的數據進行回調給ui線程
           protected void deliverResponse(T response) {
                     mListener.onResponse(response);
           }

}

案例：

url :"http://www.weather.com.cn/data/sk/101010100.html"
return result:
                    {"weatherinfo": {"city":"北京","cityid":"101010100","temp":"19",
                             "WD":"南風","WS":"2級","SD":"43%", "WSE":"2","time":"19:45","isRadar":"1",
                              "Radar":"JC_RADAR_AZ9010_JB"}
                     }
第五步：定義實體類和引用類（根據實際返回結果寫）
/**
 * 實體類的引用類
 *
 * @author  Administrator
 *
 */
public class Entity_Quote {
            private Entity  weatherinfo;

            public Entity getEntity() {
               return entity;
              }

            public void setEntity(Entity entity) {
                   this.entity = entity;
            }
}

/**
 * 實體類
 * @author  Administrator
 *
 */
public class Entity {
             private String city;
             private String temp;
             private String time;
             public String getCity() {
                 return city;
             }
             public void setCity(String city) {
                 this.city = city;
             }
             public String getTemp() {
                  return temp;
             }
             public void setTemp(String temp) {
                   this.temp = temp;
             }
            public String getTime() {
                  return time;
             }
            public void setTime(String time) {
                 this.time = time;
             }
   
}

第六步：activity中使用
public class MainActivity extends Activity {
               TextView tv;
               public String url=  "http://www.weather.com.cn/data/sk/101010100.html";
               public  final static String  TAG=MainActivity.class.getSimpleName();
                @Override
               protected void onCreate(Bundle savedInstanceState) {
                        super.onCreate(savedInstanceState);
                        setContentView(R.layout.activity_main);
                         tv = (TextView) findViewById(R.id.mian_tv);
 
                       sendRequest();
              }

            //volley適合數據量小且通訊頻繁，可是不可用數據大的操做，如流媒體，下載文件（downloadManager）等。
           private void sendRequest() {
                 GsonRequest<Entity_Quote>  gsonRequest= 

                                   new GsonRequest<Entity_Quote>(url,Entity_Quote.class,new   Listener<Entity_Quote>() {                                                                @Override                                        public void onResponse(Entity_Quote quote) {//返回一個引用類，經過引用類拿到實體類                                                        Entity entity=quote.getEntity();                                                        tv.setText(entity.getCity()+""+entity.getTemp()+""+entity.getTime());                                            }                                    }, new ErrorListener() {                                      @Override                                        public void onErrorResponse(VolleyError error) {                                            Log.e("TAG", error.getMessage(), error);                                     }                                });                      gsonRequest.setTag(TAG);//添加標記，便於取消                      MySingleton.getInstance(this).addToRequestQueue(gsonRequest);                      //能夠在任何線程中添加一個請求，    可是響應結果都是返回在主線程中            }            @Override            protected void onStop() {                   RequestQueue mQueue=MySingleton.getInstance(this.getApplicationContext()).getRequestQueue();                    if(mQueue!=null){                    mQueue.cancelAll(TAG);//取消用TAG標記的request                   }                     super.onStop();            }}