第一个是我的客户端，第二个是服务器端，为什么客户端不能通过socket向服务器发送第二轮消息？当你在控制台里放东西的时候，服务器会通过socket响应，然后把消息发送回客户端。但是当我第二次在控制台里放东西的时候，消息就不能再发送到服务器了，请告诉我为什么。谢谢

package client;
import java.io.*;
import java.net.*;
import java.util.Scanner;
public class Client {
static Socket sock ;
static InputStreamReader IR;
public static void main(String[] args) throws IOException, 
InterruptedException 
{
Client client = new Client();
sock = new Socket("localhost", 1112);
IR = new InputStreamReader(sock.getInputStream());
client.run();
}
public void run() throws IOException, InterruptedException
{
    while(true)
    {
    PrintStream PS = new PrintStream(sock.getOutputStream());
    Scanner sc = new Scanner(System.in); 
    System.out.println("Enter your age："); 
    int age = sc.nextInt(); 
    PS.println(age);
    if(age == 0)
  {
    break;
  }
    System.out.println("here");
    BufferedReader BR = new BufferedReader(IR);
    String MSG = BR.readLine();
    System.out.println("client: server has received "+MSG);
    Thread.sleep(1000);
    }
    sock.close();
}
}
package server;
import java.io.*;
import java.net.*;
public class Server {
static ServerSocket serverSocket;
public static void main(String[] args) throws IOException, 
InterruptedException {
    Server server = new Server();
    serverSocket = new ServerSocket(1112);
    server.run();
}
public void run() throws IOException, InterruptedException
{
       while(true)
      {
           //ServerSocket serverSocket = new ServerSocket(1112);
           Socket socket = serverSocket.accept();
           InputStreamReader IR = new 
    InputStreamReader(socket.getInputStream());
           BufferedReader BR = new BufferedReader(IR);
           String msg = BR.readLine();
           System.out.println("server: I have received "+msg);
           Thread.sleep(2000);
           if(msg != null)
           {
               PrintStream PS = new 
PrintStream(socket.getOutputStream());
               PS.println(msg);
           }else
           {
               break;
           }
    }
       serverSocket.close();
}
}