[JAVA 실습 #2] TCP Echo Server/Client - 전문 통신 (fixed length) - 전문 길이(byte) 읽기

자바(JAVA) 실습 - TCP Echo Server/Client - 전문 통신 (fixed length)

 

Server

1. 전문의 첫 8byte에 전문의 전체 길이

2. 41번째 바이트부터 9byte는 인터페이스 아이디 - 인터페이스 아이디를 기준으로 조건 설정

3. 들어온 메세지를 그대로 client에게 전송

4. 전송 후 대기

 

Client

1. 전문의 첫 8byte에 전문의 전체 길이

2. 41번째 바이트부터 9byte는 인터페이스 아이디 - 인터페이스 아이디를 기준으로 조건 설정

3. 전문을 Server에 전송

4. 들어온 메세지 표시

5. 메세지 표시 후 종료

 

 

Server

 

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
 
public class TcpServerExample {
    
    public static void main(String[] args) {
 
        ServerSocket serverSocket = null;
 
        try {
            serverSocket = new ServerSocket();
            serverSocket.bind(new InetSocketAddress("localhost", 9091));
 
            while (true) {
                System.out.println("\n[ Waiting ... ] \n");
                Socket socket = serverSocket.accept();
                InetSocketAddress isa = (InetSocketAddress) socket.getRemoteSocketAddress();
                System.out.println("\n[ Accept ... ] \n" + isa.getHostName() + ":" + isa.getPort());
 
                byte[] bytes = null;
                String header = null;
                String message = null;
 
                InputStream is = socket.getInputStream();
                DataInputStream dis = new DataInputStream(is);
                byte[] header_bytes = new byte[8];
                int readHeader = dis.read(header_bytes);
                header = new String(header_bytes, 0, readHeader, "UTF-8");
                System.out.println("\n[ Data Length ] \n" + header);
 
                int length = Integer.parseInt(header);
                bytes = new byte[length];
                int readMessage = is.read(bytes);
 
                // Get Interface ID
                byte[] if_id_byte = new byte[9];
                System.arraycopy(bytes, 33, if_id_byte, 0, if_id_byte.length);
                String if_id_str = new String(if_id_byte, "UTF-8");
                System.out.println("\n[ Interface ID ] \n" + if_id_str);
 
                message = new String(bytes, 0, readMessage, "UTF-8");
                System.out.println("\n[ Data Received ] \n" + message);
 
                OutputStream os = socket.getOutputStream();
                DataOutputStream dos = new DataOutputStream(os);
                message = header + message;
                bytes = message.getBytes("UTF-8");
 
                dos.write(bytes);
                dos.flush();
 
                System.out.println("\n[ Data Send Success ] \n" + message);
 
                dos.close();
                os.close();
                dis.close();
                is.close();
 
                socket.close();
                System.out.println("\n[ Socket closed ]\n");
            }
 
        } catch (Exception e) {
            e.printStackTrace();
        }
 
        if (!serverSocket.isClosed()) {
            try {
                serverSocket.close();
                System.out.println("\n[ Socket closed ]\n");
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
 
}

 

 

Client

 

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.Socket;
 
public class TcpClientExample {
    
    public static void main(String[] args) {
 
        Socket socket = null;
 
        try {
            socket = new Socket();
            System.out.println("\n[ Request ... ]\n");
            socket.connect(new InetSocketAddress("localhost", 9091));
            System.out.println("\n[ Success ... ]\n");
 
            byte[] bytes = null;
            String message = null;
            OutputStream os = socket.getOutputStream();
            message = "00000243@@ae-6y@@                        IF0000001  127.0.0.1                                          D1SS202010201016210551101621000202010201016210551UC                           AA00000058123                     234                 345           @@";
            bytes = message.getBytes("UTF-8");
 
            os.write(bytes);
            os.flush();
            System.out.println("\n[ Data Send Success ]\n" + message);
 
            InputStream is = socket.getInputStream();
            bytes = new byte[500];
            int readByteCount = is.read(bytes);
            message = new String(bytes, 0, readByteCount, "UTF-8");
            System.out.println("\n[ Data Received ]\n" + message);
 
            os.close();
            is.close();
 
            socket.close();
            System.out.println("\n[ Socket closed ]\n");
 
        } catch (Exception e) {
            e.printStackTrace();
        }
 
        if (!socket.isClosed()) {
            try {
                socket.close();
                System.out.println("\n[ Socket closed ]\n");
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
 
    }
 
}

 

 

Server

 

Client