socket

server:

import java.io.*;
import java.net.*;

public class MyServer extends Thread {
 private Socket client;
 public MyServer(Socket s) {
  this.client = s;
 }
 public void run() {
  try {
   InputStream is = client.getInputStream();
   BufferedReader in = new BufferedReader(new InputStreamReader(is));
   PrintWriter out=new PrintWriter(client.getOutputStream());
   while(true) {
    String str = in.readLine();
    System.out.println(str);
    out.println("has receive....");
    out.flush();
    if(str.equals("end"))
     break;    
   }
   client.close();
  } catch (IOException e) {
   
  }
 }
 
 public static void main(String[] args) throws IOException{
  ServerSocket server = new ServerSocket(5678);
  while(true){
   MyServer myserver = new MyServer(server.accept());
   myserver.start();
  }
 }
 
}

client:

import java.net.*;
import java.io.*;

public class Client{
 static Socket server;
 
 public static void main(String[] args) throws Exception {
  server=new Socket(InetAddress.getLocalHost(),5678);
  BufferedReader in=new BufferedReader(new InputStreamReader(server.getInputStream()));
  PrintWriter out=new PrintWriter(server.getOutputStream());
  BufferedReader wt=new BufferedReader(new InputStreamReader(System.in));
  
  while(true) {
   String str=wt.readLine();
   out.println(str);
   out.flush();
   if(str.equals("end")) {
    break;
   }
   System.out.println(in.readLine());
  }
  server.close();
 }
}