Socket TCP/UDP

---

TCP

TCPClient

 package com.tcp;
 
 import java.io.*;
 import java.net.*;
 
 class TCPClient
 {
     public static void main(String argv[]) throws Exception
     {
         String sentence;
         String modifiedSentence;
         BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
 
         Socket clientSocket = new Socket("127.0.0.1", 6789);
         DataOutputStream outToServer = 
　　　　　　　　new DataOutputStream(clientSocket.getOutputStream());
         BufferedReader inFromServer = 
　　　　　　　　new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
         sentence = inFromUser.readLine();
         outToServer.writeBytes(sentence + '\n');
         modifiedSentence = inFromServer.readLine();
         System.out.println("FROM SERVER: " + modifiedSentence);
         clientSocket.close();
     }
 }

TCPServer

 package com.tcp;
 
 import java.io.*;
 import java.net.*;
 
 class TCPServer
 {
    public static void main(String argv[]) throws Exception
       {
          String clientSentence;
          String capitalizedSentence;
          ServerSocket welcomeSocket = new ServerSocket
          (6789);
 
          while(true)
          {
             Socket connectionSocket = welcomeSocket.accept();
 
             BufferedReader inFromClient =
　　　　　　　　　　　new BufferedReader
　　　　　　　　　　(new InputStreamReader(connectionSocket.getInputStream()));
 
             DataOutputStream outToClient =
　　　　　　　　　　　new DataOutputStream(connectionSocket.getOutputStream());
             clientSentence = inFromClient.readLine();
             capitalizedSentence =  clientSentence.toUpperCase() + '\n';
             outToClient.writeBytes(capitalizedSentence);
          }
       }
 }

---

UDP

UDPClient

 package com.udp;
 
 import java.io.*;
 import java.net.*;
 
 class UDPClient
 {
    public static void main(String args[]) throws Exception
    {
       BufferedReader inFromUser =
　　　　　　　　new BufferedReader(new InputStreamReader(System.in));
       DatagramSocket clientSocket = new DatagramSocket();
       InetAddress IPAddress = InetAddress.getByName("localhost");
       byte[] sendData = new byte[1024];
       byte[] receiveData = new byte[1024];
       String sentence = inFromUser.readLine();
       sendData = sentence.getBytes();
       DatagramPacket sendPacket =
　　　　　　　　new DatagramPacket(sendData, sendData.length, IPAddress, 9876);
       clientSocket.send(sendPacket);
       DatagramPacket receivePacket =
　　　　　　　　new DatagramPacket(receiveData,receiveData.length);
       clientSocket.receive(receivePacket);
       String modifiedSentence = new String(receivePacket.getData());
       System.out.println("FROM SERVER:" +modifiedSentence);
       clientSocket.close();
    }
 }

UDPServer

 package com.udp;
 
 import java.io.*;
 import java.net.*;
 
 class UDPServer
 {
    public static void main(String args[]) throws Exception
       {
          DatagramSocket serverSocket = new
                               DatagramSocket(9876);
             byte[] receiveData = new byte[1024];
             byte[] sendData = new byte[1024];
             while(true)
                {
                   DatagramPacket receivePacket =
　　　　　　　　　　　　　　new DatagramPacket(receiveData, receiveData.length);
                   serverSocket.receive(receivePacket);
                   String sentence = new String(receivePacket.getData());
                   InetAddress IPAddress = receivePacket.getAddress();
                   int port = receivePacket.getPort();
                   String capitalizedSentence = sentence.toUpperCase();
                   sendData = capitalizedSentence.getBytes();
                   DatagramPacket sendPacket =
　　　　　　　　　　　　　　new DatagramPacket(sendData,sendData.length, IPAddress, port);
                   serverSocket.send(sendPacket);
                }
       }
 }