[안드로이드] Url에 요청해서 Json 받아오기 (Get)

1. 메니페스트에 인터넷 권한 

<uses-permission android:name="android.permission.INTERNET"/>

2. xml 만들기

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/textView"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="데이터 가져오기"
            android:textAlignment="center" />

        <Button
            android:id="@+id/button"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="JSON" />

        <Button
            android:id="@+id/button3"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="테스트" />

    </LinearLayout>

    <EditText
        android:id="@+id/editText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="textPersonName"
        android:text="값을 넣으세요." />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/textView4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Get방식 api 가져오기" />

        <Button
            android:id="@+id/button2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Get Json" />
    </LinearLayout>

    <EditText
        android:id="@+id/editText2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="textPersonName"
        android:text="800" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <TextView
            android:id="@+id/textView2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="* 결과창"
            android:textSize="18sp"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/textView3"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="TextView" />
    </LinearLayout>
</LinearLayout>

3. 코드쓰기

package com.example.acid.jsonpost;

import android.os.AsyncTask;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.JsonReader;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.ObjectOutput;
import java.io.OutputStream;
import java.lang.ref.WeakReference;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.concurrent.ExecutionException;

public class MainActivity extends AppCompatActivity implements View.OnClickListener, Runnable {

    Button button;
    TextView textView;
    EditText editText;

    Button buttonGet;
    EditText editTextGet;

    TextView textViewSet;

    Button buttonTest;

    String getEditText = "";
    String resultData ="";



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

        //Result TextView
        textView = findViewById(R.id.textView3);

        //Post Json 요청
        button = findViewById(R.id.button);
        editText = findViewById(R.id.editText);

        //Get Json 요청
        buttonGet = findViewById(R.id.button2);
        editTextGet = findViewById(R.id.editText2);

        textViewSet = findViewById(R.id.textView);

        buttonTest = findViewById(R.id.button3);

        //setOnClick connect
        button.setOnClickListener(this);
        buttonTest.setOnClickListener(this);
        buttonGet.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {

        switch (v.getId()) {
            case R.id.button: // Json 보내기
                Toast.makeText(getApplicationContext(), "button1을 눌렀습니다.", Toast.LENGTH_LONG).show();
                getEditText = editText.getText().toString();
                resultData = JsonPost(getEditText);

                textView.setText(resultData);
                break;

            case R.id.button2: // Get방식 Json 가져오기
                Toast.makeText(getApplicationContext(), "button2을 눌렀습니다.", Toast.LENGTH_LONG).show();
                getEditText = editTextGet.getText().toString();
                try {
                    Thread thread = new Thread(this);
                    thread.start();
                } catch (Exception e) {
                    e.printStackTrace();
                }


                break;

            case R.id.button3: //
                Toast.makeText(getApplicationContext(), "테스트버튼.", Toast.LENGTH_LONG).show();

                break;
        } //Switch
    }


    public String JsonPost(String getEditText) {
        return "";
    }

    @Override
    public void run() {
        //http://www.nlotto.co.kr/common.do?method=getLottoNumber&drwNo=805
        String address = "http://www.nlotto.co.kr/common.do?method=getLottoNumber&drwNo=" + getEditText;
        String resultData = "";

        try {
            URL url = new URL(address);
            HttpURLConnection httpCon = (HttpURLConnection) url.openConnection();
            //GET or Post 설정
            httpCon.setRequestMethod("GET");
            //커넥션 타임아웃 설정 (서버 접속시 연결시간)
            httpCon.setConnectTimeout(10 * 1000);
            //Read시 타임아웃 설정
            httpCon.setReadTimeout(10 * 1000);
            // User-Agent 설정
            httpCon.setRequestProperty("User-Agent", "Mozilla/9.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36");

/*            // Request Header값 셋팅 setRequestProperty(String key, String value)
            httpCon.setRequestProperty("NAME", "name");
            httpCon.setRequestProperty("MDN", "mdn");
            httpCon.setRequestProperty("APPID", "appid");
            // 서버 Response Data를 xml 형식의 타입으로 요청.
            httpCon.setRequestProperty("Accept", "application/xml");
            // 서버 Response Data를 JSON 형식의 타입으로 요청.
            httpCon.setRequestProperty("Accept", "application/json");
            // 타입설정(text/html) 형식으로 전송 (Request Body 전달시 text/html로 서버에 전달.)
            httpCon.setRequestProperty("Content-Type", "text/html");
            // 타입설정(text/html) 형식으로 전송 (Request Body 전달시 application/xml로 서버에 전달.)
            httpCon.setRequestProperty("Content-Type", "application/xml");
            // 타입설정(application/json) 형식으로 전송 (Request Body 전달시 application/json로 서버에 전달.)
            httpCon.setRequestProperty("Content-Type", "application/json");
             // 컨트롤 캐쉬 설정
            httpCon.setRequestProperty("Cache-Control", "no-cache");
            // 타입길이 설정(Request Body 전달시 Data Type의 길이를 정함.)
            httpCon.setRequestProperty("Content-Length", "length")*/

            //여기서 연결한다
            httpCon.connect();

            //Response code 불러오기
            int code = httpCon.getResponseCode();
            Log.d("Response Code", code + "");

            if (code == 200) { //정상처리 200

                //InputStream으로 읽어들인다.
                InputStream response = httpCon.getInputStream();
                InputStreamReader inputStreamReader = new InputStreamReader(response, "UTF-8");
                //버퍼 리더로 변환
                BufferedReader bf = new BufferedReader(inputStreamReader);

                StringBuffer sb = new StringBuffer();
                String line;
                while ((line = bf.readLine()) != null) {
                    sb.append(line);
                }
                resultData = sb.toString();

                Log.d("Json", resultData);

                response.close();
                bf.close();


            } else { // 에러
                resultData = "None";
            }

            httpCon.disconnect();




        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        Message message = mHandler.obtainMessage(101, resultData);
        mHandler.sendMessage(message);
    }

    private final MyHandler mHandler = new MyHandler(this);
    public static class MyHandler extends Handler{
        private final WeakReference<MainActivity> weakReference;

        public MyHandler(MainActivity mainActivity) {
            weakReference = new WeakReference<MainActivity>(mainActivity);
        }

        @Override
       public void handleMessage(Message msg) {
           super.handleMessage(msg);

            MainActivity mainactivity = weakReference.get();

            if (mainactivity != null) {
                switch (msg.what) {

                    case 101:
                        String jsonString = (String)msg.obj;
                        String result = "";
                        try {
                            //String to Json
                            JSONObject jsonObj = new JSONObject(jsonString);
                            result = jsonObj.getString("firstAccumamnt");
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                        mainactivity.textView.setText(result);

                        break;
                }
            }
       }
   }
}

주의점

Thread로 구현을 해야 한다. Task하고 Thread가 있는데 Thread가 범용성이 있는거 같아서 그쪽 코드를 참조했다.

작업을 완료하면 Handler로 보내서 Handler에서 구분된 코드로 작업을 실행한다.