retrofit:2.2.0 framework has powerful functions and excellent encapsulation in network loading. Today we will learn about its basic usage

1. Import dependency:

    implementation 'com.squareup.retrofit2:retrofit:2.2.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.2.0'

2. Initialize the Retrofit object

//Obviously, we can see that the framework of Retrofit adopts the builder pattern
Retrofit retrofit = new Retrofit.Builder()
        .baseUrl(Contant.BASE_URL)
        .addConverterFactory(GsonConverterFactory.create())
        .build()
/**
 *It is necessary to explain the base uurl. The string represents the top level of the server connection
 * For example: 
 * https://mp.csdn.net/mdeditor/a.png
 * https://mp.csdn.net/mdeditor/c.png
 * https://mp.csdn.net/mdeditor/mm/.png
 * https://mp.csdn.net/mdeditor/yh.png
 * https://mp.csdn.net/mdeditor/my.png
 * name The BASE_URL here is https://mp.csdn.net/mdeditor/
 * It can be understood as root url
  */        

3. Develop network request entity

    responseInfoAPI = retrofit.create(ResponseInfoAPI.class)
     /**
       * Here, we need to focus on the responseinfo API, which is named by itself. It doesn't matter what it is called. It's mainly about the contents
       */

public interface ResponseInfoAPI {
    //Specify request method
    //Full link address requested
    //Request method, request parameter
    //Requested results
    //http://10.0.2.2:8080/TakeoutServiceVersion2

    @GET(Contant.HOME_URL)
    Call<ResponseInfo> getHomeInfo(@Query("latitude") String latitude, @Query("longitude") String longitude);
}
 /**
   * 1,Many people are confused when they see it. Readers can first see it as a common interface
   * getHomeInfo(String latitude,String longitude)
   * 2,Next, @ get (contact. Home? URL) means to pass in the home? URL connection. Note that the home? URL here will be spliced behind the previous base? URL to form a complete URL link. In the form of get
   * @GET(Contant.HOME_URL)
   * getHomeInfo(String latitude,String longitude)
   * 3,The complete url is formed, but relevant parameters need to be passed in. Here, the parameters are string latitude and string longitude. In retrofit, a flag is used to represent the parameters passed in get, namely @ Query("latitude")
   * 4，Last with a return value
   * @GET(Contant.HOME_URL)
   * Call<ResponseInfo> getHomeInfo(@Query("latitude") String latitude, @Query("longitude") String 
   * 5，The return value here is defined by you, but it must correspond to your data
   */

3. Trigger call

public class HomePresenter extends BasePresenter {
    @Override
    protected void showError(String message) {

    }

    @Override
    protected void parseJson(String json) {
        //Parse JSON here
        Gson gson = new Gson();
        gson.fromJson(json, HomeInfo.class)
    }
    //Trigger network request
    public void getHomeData(String lat,String lon){
        Call<ResponseInfo> homeInfo = responseInfoAPI.getHomeInfo(lat, lon);
        //Trigger successful or failed callback methods in callback
        homeInfo.enqueue(new CallBackAdapter());
    }
}