前言

Retrofit 是一个 RESTful 的 HTTP 网络请求框架的封装，网络请求的工作本质上是 OkHttp 完成，而 Retrofit 仅负责 网络请求接口的封装
参考文章
https://www.jianshu.com/p/865e9ae667a0
https://blog.csdn.net/carson_ho/article/details/73732076

一、Retrofit的简单实用

1.1、引入依赖

implementation 'com.squareup.retrofit2:retrofit:2.0.2'
 implementation 'com.squareup.retrofit2:converter-gson:2.0.2'
 implementation 'com.google.code.gson:gson:2.8.5'
implementation 'com.squareup.retrofit2:adapter-rxjava:2.0.2'

1.2、根据Http接口创建Java接口

package com.enjoy.networkdemo;

import java.util.Map;

import okhttp3.RequestBody;
import okhttp3.ResponseBody;
import retrofit2.Call;
import retrofit2.Response;
import retrofit2.http.Body;
import retrofit2.http.Field;
import retrofit2.http.FormUrlEncoded;
import retrofit2.http.GET;
import retrofit2.http.HEAD;
import retrofit2.http.HTTP;
import retrofit2.http.Header;
import retrofit2.http.Headers;
import retrofit2.http.POST;
import retrofit2.http.Path;
import retrofit2.http.Query;
import retrofit2.http.QueryMap;
import retrofit2.http.Url;

public interface HttpbinService {

    /**
     * @FormUrlEncoded请求参数的格式
     * @Field 服务器需要的参数名称
     * @param userName
     * @param pwd
     * @return
     */
    @POST("post")
    @FormUrlEncoded   //请求参数的格式
    Call<ResponseBody> post(@Field("username") String userName, @Field("password") String pwd);

    /**
     * Query服务器需要的参数名称
     * @param userName
     * @param pwd
     * @return
     */
    @GET("get")
    Call<ResponseBody> get(@Query("username") String userName, @Query("password") String pwd);

}

1.3、MainActivity.java

核心

 retrofit = new Retrofit.Builder().baseUrl("https://www.httpbin.org/").build();
 httpbinService = retrofit.create(HttpbinService.class);

package com.enjoy.networkdemo;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;

import org.jetbrains.annotations.NotNull;

import java.io.IOException;

import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.FormBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.ResponseBody;
import retrofit2.Retrofit;


public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";
    private OkHttpClient okHttpClient;
    private Retrofit retrofit;
    private HttpbinService httpbinService;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        okHttpClient = new OkHttpClient();
        retrofit = new Retrofit.Builder().baseUrl("https://www.httpbin.org/").build();
        httpbinService = retrofit.create(HttpbinService.class);
    }

    public void postAsync(View view) {

        retrofit2.Call<ResponseBody> call = httpbinService.post("xxxx", "123456");
        call.enqueue(new retrofit2.Callback<ResponseBody>() {
            @Override
            public void onResponse(retrofit2.Call<ResponseBody> call, retrofit2.Response<ResponseBody> response) {
                try {
                    Log.i(TAG, "postAsync: " + response.body().string());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onFailure(retrofit2.Call<ResponseBody> call, Throwable t) {

            }
        });
    }
}

二、测试