[Do it 개정6판_안드로이드 스튜디오]둘째마당_10 서버에 데이터 요청하고 응답받기

- 단말에서 독집적으로 동작하는 앱을 만들기 보다는 서버에 있는 데이터를 요청에서 사용하는 경우가 많다. 

 

10-1 네트워킹이란?

■ 네트워크 연결 방식 이해하기

 

10-2 소켓 사용하기

■ HTTP 프로토콜과 소켓

 

>SampleSocket 프로젝트

 

▼MainActivity.java

package com.ogrg.techtown.push.socket;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.preference.PreferenceActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;

public class MainActivity extends AppCompatActivity {
    EditText editText;

    TextView textView, textView2;

    Handler handler = new Handler();

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

        editText = findViewById(R.id.editText);
        textView = findViewById(R.id.textView);
        textView2 = findViewById(R.id.textView2);

        Button button = findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                final String data = editText.getText().toString();
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        send(data);
                    }
                }).start();
            }
        });

        Button button2 = findViewById(R.id.button2);
        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        startServer();
                    }
                }).start();
            }
        });
    }

    public void printClientLog(final String data) {
        Log.d("MainActivity", data);
        handler.post(new Runnable() {
            @Override
            public void run() {
                textView.append(data + "\n");
            }
        });
    }

    public void printServerLog(final String data) {
        Log.d("MainActivity", data);

        handler.post(new Runnable() {
            @Override
            public void run() {
                textView2.append(data + "\n");
            }
        });
    }

    public void send(String data){
        try {
            int portNumber = 5001;
            Socket sock = new Socket("localhost", portNumber);
            printClientLog("소켓 연결함");
            ObjectOutputStream outstream = new ObjectOutputStream(sock.getOutputStream());
            outstream.writeObject(data);
            outstream.flush();
            printClientLog("데이터 전송함.");

            ObjectInputStream inStream = new ObjectInputStream(sock.getInputStream());
            printClientLog("서버로부터 받음: " + inStream.readObject());
            sock.close();
        } catch (Exception ex){
            ex.printStackTrace();
        }
    }


    public void startServer() {
        try {
            int portNumber = 5001;

            ServerSocket server = new ServerSocket(portNumber);
            printServerLog("서버 시작함: " + portNumber);
            while (true){
                Socket sock = server.accept();
                InetAddress clientHost = sock.getLocalAddress();
                int clientPort = sock.getPort();
                printServerLog("클라이언트 연결됨" + clientHost + " : "+clientPort);

                ObjectInputStream instream = new ObjectInputStream(sock.getInputStream());
                Object obj = instream.readObject();
                printServerLog("데이터 받음:" + obj);

                ObjectOutputStream outstream = new ObjectOutputStream(sock.getOutputStream());
                outstream.writeObject(obj + "from Server");
                outstream.flush();
                printServerLog("데이터 보냄");

                sock.close();
            }
        }catch (Exception ex){
            ex.printStackTrace();
        }
    }

}

▼activity_main.xml

<?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="0dp"
        android:layout_weight="1"
        android:background="#0277BD"
        android:orientation="vertical">

        <EditText
            android:id="@+id/editText"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:ems="10"
            android:inputType="textPersonName"
            android:text="Name"
            android:textSize="20sp"/>

        <Button
            android:id="@+id/button"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="전송" />

        <ScrollView
            android:layout_width="match_parent"
            android:layout_height="match_parent">

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

                <TextView
                    android:id="@+id/textView"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:textSize="20sp"
                     />
            </LinearLayout>
        </ScrollView>
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:orientation="vertical">

        <Button
            android:id="@+id/button2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="서버 시작" />

        <ScrollView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="#F9A825">

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

                <TextView
                    android:id="@+id/textView2"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:textSize="20sp"/>
            </LinearLayout>
        </ScrollView>

    </LinearLayout>
</LinearLayout>