1、首先添加依赖 

implementation ('com.squareup.okhttp3:okhttp:3.10.0')

2、测试网址

​​https://httpbin.org/​​

3、GET同步请求

public void get_sync(View view) {
    new Thread(new Runnable() {
        @Override
        public void run() {
            Request request = new Request.Builder().url("https://httpbin.org/get?a=1&b=2").build();
            //准备请求的call对象
            Call call = okHttpClient.newCall(request);
            try {
                Response response = call.execute();
                Log.e(TAG, "get_sync: "+response.body().string() );
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }).start();

}

4、GET异步请求

//异步请求
public void get_nosync(View view) {
    Request request = new Request.Builder().url("https://httpbin.org/get?a=1&b=2").build();
    //准备请求的call对象
    Call call = okHttpClient.newCall(request);
    call.enqueue(new Callback() {

        @Override
        public void onFailure(Call call, IOException e) {
            Log.e(TAG, "onFailure: ");
        }

        @Override
        public void onResponse(Call call, Response response) throws IOException {
            if (response.isSuccessful())//成功
                Log.d(TAG, "onResponse: " + response.body().string());
            else
            {
                Log.e(TAG, "onFailure: ");
            }
        }

    });

}

5、POST同步请求

public void post_sync(View view) {
   new Thread(new Runnable() {
       @Override
       public void run() {
           RequestBody requestBody = new FormBody.Builder()
                   .add("a", "1")
                   .add("b", "2")
                   .build();

           Request request = new Request.Builder().url("https://httpbin.org/post")
                   .post(requestBody)
                   .build();
           //准备请求的call对象
           Call call = okHttpClient.newCall(request);
           try {
               Response response = call.execute();
               Log.e(TAG, "get_sync: "+response.body().string() );
           } catch (IOException e) {
               e.printStackTrace();
           }
       }
   }).start();
}

6、POST异步请求

public void post_nosync(View view) {
   RequestBody requestBody = new FormBody.Builder()
           .add("a", "1")
           .add("b", "2")
           .build();

   Request request = new Request.Builder().url("https://httpbin.org/post")
           .post(requestBody)
           .build();
   //准备请求的call对象
   Call call = okHttpClient.newCall(request);
   call.enqueue(new Callback() {
       @Override
       public void onFailure(Call call, IOException e) {
           Log.e(TAG, "onFailure: ");
       }

       @Override
       public void onResponse(Call call, Response response) throws IOException {
           if (response.isSuccessful())//成功
               Log.d(TAG, "onResponse: " + response.body().string());
           else
           {
               Log.e(TAG, "onFailure: ");
           }
       }
   });
}