• ChatServer

package ch03_chat;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

public class ChatServer {

	public static void main(String[] args) {
		
		Scanner scanner = new Scanner(System.in);
		
		// 서버
		ServerSocket listener = null;
		Socket socket = null;
		BufferedReader sin = null;
		BufferedWriter sout = null;
		
		try {
			
			listener = new ServerSocket(10000);  // 서버 소켓 생성
			System.out.println("- Server 준비 -");
			
			socket = listener.accept(); // 클라이언트로 부터 연결 요청 대기
			
			sin = new BufferedReader(new InputStreamReader(socket.getInputStream()));   // 서버 수신
			sout = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));// 서버 송신
			
			String inputMessage = null;
			while(true) {
				inputMessage = sin.readLine(); // 클라이언트가 전송한 데이터 읽기
				if(inputMessage.equals("end")) {
					System.out.println("- 연결 종료 -");
					break;
				}
				System.out.println("sin : " + inputMessage);
				System.out.println();
				
				System.out.print("서버 입력 > ");
				String outputMessage = scanner.nextLine();
				sout.write(outputMessage + "\\n");
				sout.flush();
			}
			
		} catch (Exception e) {
			System.out.println("서버 error~");
		} finally {
			try {
				if(sout != null) sout.close();
				if(sin != null) sin.close();
				if(socket != null) socket.close();
				if(listener != null) listener.close();
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		
	}
	
}

• ChatClient

package ch03_chat;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.util.Scanner;

public class ChatClient {

	public static void main(String[] args) {
		
		Scanner scanner = new Scanner(System.in);
		
		// 클라이언트
		Socket socket = null;
		BufferedReader cin = null;
		BufferedWriter cout = null;
		
		try {
			
			socket = new Socket("localhost", 10000);
			System.out.println("서버 연결...");
			
			cin = new BufferedReader(new InputStreamReader(socket.getInputStream()));    // 클라이언트 수신
			cout = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())); // 클라이언트 송신
			
			String outputMessage = null;
			while(true) {
				System.out.print("클라이언트 입력 > ");
				outputMessage = scanner.nextLine();
				if(outputMessage.equals("end")) {
					cout.write(outputMessage + "\\n");
					cout.flush();
					break;
				}
				cout.write(outputMessage + "\\n");
				cout.flush();
				System.out.println();
				
				String inputMessage = cin.readLine(); // 서버가 전송한 데이터
				System.out.println("cin : " + inputMessage);
				
			}

			
		} catch (Exception e) {
			System.out.println("클라이언트 error~");
		} finally {
			try {
				if(cin != null) cin.close();
				if(cout != null) cout.close();
				if(socket != null) socket.close();
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		
	}
	
}