[JAVA] OkHttp3 (GET, POST) in Android Studio

Use OkHttp3 to make GET and POST requests.

What I made

MainActivity

MainActivity.java

package com.example.sampleapplication.sample.okhttp;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Get GET button and POST button
        Button getButton = findViewById(R.id.getButton);
        Button postButton = findViewById(R.id.postButton);

        //When the GET button is tapped
        getButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                OkHttpGet getTask = new OkHttpGet();
                getTask.execute();
            }
        });

        //When the POST button is pressed
        postButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                OkHttpPost postTask = new OkHttpPost();
                postTask.execute();
            }

        });
    }
}

This time, I created separate classes for Get and Post, and called them. Each get.Task.execute(); postTask.execute(); I'm calling with.

GET

OkHttpGet.java

package com.example.sampleapplication.sample.okhttp;

import android.os.AsyncTask;
import android.util.Log;

import java.io.IOException;

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class OkHttpGet extends AsyncTask<String,String,String> {
    @Override
    protected String doInBackground(String... strings) {

        // url
        String url = "GET request endpoint";
        //Response data
        String strData = "";

        //Instantiation of OkHttp
        OkHttpClient client = new OkHttpClient();

        //Build request including url
        Request request = new Request.Builder()
                .url(url)
                .get()
                .build();

        try {
            //Request execution
            Response response = client.newCall(request).execute();
            //Get data from the body of the response
            strData = response.body().string();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return strData;
    }

    @Override
    protected void onPostExecute(String str) {
        Log.d("Debug",str);
    }
}

This time, I set the URL including the query in url. It seems that time-consuming processing cannot be executed in the main thread, so AsyncTask is used for asynchronous processing. Do a time-consuming process (here, a request using OkHttp) in doInBackground, and when it's done It feels like the process moves to onPostExecute. onPostExecute returns the result of asynchronous processing performed by doInBackground to the main thread. So if you want to display the result of the request on the screen, you can do it in this. Perhaps.

POST

OkHttpPost.java

package com.example.sampleapplication.sample.okhttp;

import android.os.AsyncTask;
import android.util.Log;

import java.io.IOException;

import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class OkHttpPost extends AsyncTask<String,String,String> {

    public static final MediaType JSON = MediaType.get("application/json; charset=utf-8");
    String json = "{\"name\":\"name\", \"taxis\":\"Classification\"}";

    @Override
    protected String doInBackground(String... strings) {

        OkHttpClient client = new OkHttpClient();

        String url = "URL used for POST";
        RequestBody body = RequestBody.create(JSON, json);

        Request request = new Request.Builder()
                .url(url)
                .post(body)
                .build();

        try {
            Response response = client.newCall(request).execute();
            return response.body().string();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
    protected void onPostExecute(String str) {
        Log.d("Debug",str);
    }
}

I am passing json format data by POST. Other than that, it is the same as GET.