Retrofit网络请求框架基础操作

Retrofit网络请求框架基础操作

Retrofit

Retrofit 是一套 RESTful 架构的 Android（Java) 客户端实现，基于注解，提供 JSON to POJO（Plain Ordinary Java Object ，简单 Java 对象），POJO to JSON，网络请求（POST，GET， PUT，DELETE 等）封装。

优点：Retrofit 是一套注解形的网络请求封装库，让我们的代码结构更给为清晰。它可以直接解析JSON数据变成JAVA对象，甚至支持回调操作，处理不同的结果。

基础操作
- Demo中使用的接口地址 :http://apis.baidu.com/heweather/weather/free
- 添加依赖

compile 'com.squareup.okhttp3: okhttp:3.2.0'
compile 'com.squareup.retrofit2: retrofit:2.0.0-beta4'
compile 'com.squareup.retrofit2: converter-gson:2.0.0-beta3'

建议：如果API返回的是JSON数据，可以利用AndroidStudio的插件GsonFormat,将JSON数据转换为Java对象。

• 创建请求接口

public interface NetRequest {
    @GET("/heweather/weather/free?/")
    Call<WeatherInfo> getWeather(@Header("apiKey")String apiKey,     @Query("city")String city);
}

讲解：
1. @GET()用来填写需要访问的接口
2. @Header用来添加Header
3. @Query用来添加输入请求的标识

• 创建网络接口服务封装类

  public class RetrofitWrapper {
  private static RetrofitWrapper instance;
  private Context mContext;
  private Retrofit retrofit;
  private RetrofitWrapper() {
  Gson gson = new Gson();
  //创建Retrofit对象
  retrofit = new Retrofit.Builder().baseUrl(Constant.BASE_URL)
  .addConverterFactory(GsonConverterFactory.create(gson))
  .build();
  }
  public static RetrofitWrapper getInstance() {
  if (instance == null) {
  synchronized (RetrofitWrapper.class){
  if (instance==null){
  instance = new RetrofitWrapper();
  }
  }
  }
  return instance;
  }
  //创建请求接口的对象
  public T create(final Class service) {
  return retrofit.create(service);
  }
  }
  讲解：
  1. BASE_URL:接口的API主机地址

• 创建功能模块类

  public class WeatherInfoModel {
  private static WeatherInfoModel weatherInfoModel;
  private NetRequest netRequest;

  public WeatherInfoModel(Context context) {
      netRequest = (NetRequest) RetrofitWrapper.getInstance().create(NetRequest.class);
  }
  
  public static WeatherInfoModel getInstance(Context context) {
      if (weatherInfoModel == null) {
          weatherInfoModel = new WeatherInfoModel(context);
      }
      return weatherInfoModel;
  }
  
  /**
   * 查询天气
   *
   * @param weatherInfoReq
   * @return
   */
  public Call<WeatherInfo> queryWeather(WeatherInfoReq weatherInfoReq) {
      Call<WeatherInfo> infoCall = netRequest.getWeather(weatherInfoReq.apiKey, weatherInfoReq.city);
      return infoCall;
  }
  

  }

• Activity类

  public class MainActivity extends Activity {
  private Button request;
  private TextView tv;
  private WeatherInfoModel weatherInfoModel;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      weatherInfoModel = WeatherInfoModel.getInstance(getApplicationContext());
      initViews();
      initParams();
      initEvent();
  }
  
  private void initEvent() {
      request.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
              //创建访问的API请求
              Call<WeatherInfo> callWeather= weatherInfoModel.queryWeather(initParams());
              final Gson gson = new Gson();
              //发送请求
              callWeather.enqueue(new Callback<WeatherInfo>() {
                  @Override
                  public void onResponse(Call<WeatherInfo> call, Response<WeatherInfo> response) {
                      if(response.isSuccessful()){
                          WeatherInfo result = response.body();
                          if(result!=null){
                             tv.setText(gson.toJson(result));
                          }
                      }
                  }
                  @Override
                  public void onFailure(Call<WeatherInfo> call, Throwable t) {
  
                  }
              });
          }
      });
  }
  

  /*
  *初始化请求参数
  */
  private WeatherInfoReq initParams() {
  WeatherInfoReq weatherInfoReq = new WeatherInfoReq();
  weatherInfoReq.apiKey = Constant.API_KEY;
  weatherInfoReq.city = Constant.CITY;
  return weatherInfoReq;
  }
  /*
  *初始化控件
  */
  private void initViews() {
  request = (Button) this.findViewById(R.id.request);
  tv = (TextView) this.findViewById(R.id.tv);
  }
  }

PS:
1.本文并未贴上所用到的Bean类和一些用到的常量，如需请到个人的github上下载源码
2.本文参考http://blog.youkuaiyun.com/u011974987/article/details/50895633