java单客户端和服务器端

package test;
import java.io.*;
import java.net.Socket;
import java.net.UnknownHostException;
//客户端
public class Client  {
   public static void main(String[] args) {
	   String hostName="";
	   int portNumber=7;
	   try {
		   Socket echoSocket=new Socket(hostName,portNumber);
		   PrintWriter out=new PrintWriter(echoSocket.getOutputStream(),true);
		   BufferedReader in=new BufferedReader(new InputStreamReader(echoSocket.getInputStream()));
		   BufferedReader stdIn=new BufferedReader(new InputStreamReader(System.in));
		   String userInput;
		   while((userInput=stdIn.readLine())!=null) {
			  out.println(userInput);
			   System.out.println("echo:"+in.readLine());
		   }
	   }catch(UnknownHostException e) {
		  e.printStackTrace();
		  System.exit(1);
	   }catch(IOException e) {
		   e.printStackTrace();
		   System.exit(1);
	   }
   }

}

package test;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
//服务器端
public class Server {
   public static void main(String[] args) {
	   try {
		   ServerSocket serverSocket=new ServerSocket(7);
		   Socket clientSocket=serverSocket.accept();
		   PrintWriter out=new PrintWriter(clientSocket.getOutputStream(),true);
		   BufferedReader in=new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
		   String inputLine;
		   while((inputLine=in.readLine())!=null) {
			   System.out.println("来自客户端："+inputLine);
			   out.println(inputLine);
		   }
	   }catch(IOException e) {
		   e.printStackTrace();
	   }
   }
}