[Third Party framework] retrofit2 (1) of network request framework -- Getting Started Guide

Retrofit2 Use steps to summarize

1. stay build.gradle I quote Retrofit library
2. Definition Interface ApiService, Inside, the configuration information of a request is declared through annotations or parameters
3. establish Retrofit object , Set it up CallAdapter And Converter
4. adopt Retrofit object Of create Method , Create an instance of the interface apiService
5. Method of calling interface instance , Initiate request .

1、 stay build.gradle I quote Retrofit library

// app-module
// Retrofit library 
implementation "com.squareup.retrofit2:retrofit:2.9.0"  
// gson-Converter 
implementation "com.squareup.retrofit2:converter-gson:2.9.0"


//  If the Library Download fails due to network reasons , You can use alicloud  maven Mirror image , At the project level build.gradle Add the following 
repositories {
        google()
		......
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
}

After adding dependency , Click on sync Take the Kula to the local .

2、 Definition ApiService

stay Retrofit in , You need to use the interface （interface） To define each request method .

PS: A name can be any name , Here the author adopts ApiSerivce, You can differentiate according to business needs , such as ApiDetails、ApiUser wait .

public interface ApiService {
    
  @GET("users/{user}/repos") //  Define the request method ,{user} Will be replaced by the parameter value passed in by the method 
  Call<List<Repo>> listRepos(@Path("user") String user);
}

3、 establish Retrofit object 、 establish API example , Initiate request

Because in the project , Basically a Retroft The object can , So here we use the singleton method to create Retrofit object , Of course , If there is a business need to create multiple Retrofit Objects can be , For example, when there are multiple BaseURL When

PS: BaseURL It can be roughly understood as domain name , Most of the App They only visit their own domain names , So there's only one BaseUrl, But it does not rule out the need for multiple domain names , Different Api Under different domain names .

Be careful ,BaseURL Must be / It's the end , Otherwise, it will report a mistake .

public class ApiServiceManager {
    
	private volatile static ApiServiceManager apiServiceManger = null;
	
	private Retrofit retrofit;
	private ApiService apiService;
	
	private ApiServiceManager() {
    
		//⒈  establish Retrofit example 
		retrofit = new Retrofit.Builder()
		.baseUrl("https://api.github.com/")
		//  take Json The result is converted to the corresponding object 
		.addConverterFactory(GsonConverterFactory.create())
    	.build();
		
		// 2.  establish ApiService example 
		apiService = retrofit.create(ApiService.class);
	}

	public void listRepos(Callback<List<Repo>> callback) {
    
		Call<List<Repo>> repos = apiService.listRepos("octocat");
		
		// 3.  Initiate request , Two ways ：execute, Don't switch threads , Execute on current thread .
		// enqueue, Switching thread , The background to perform .
		
		//  Execute the network request in the current thread 
		// Response<List<Repo>> result = repos.execute();
		
		//  Out of step request , Generally, the following methods are used 
		repos.enqueue(callback);
	}

}