使用Java语言实现一个客户端和服务器通信的功能，要求客户端与服务器之间至少有三次通信。

好的，我可以为你提供一个简单的Java代码示例，实现客户端和服务器之间的通信。这个示例包括一个服务器端和一个客户端，客户端将向服务器发送三次请求，并接收服务器的响应。

首先是服务器端的代码，它将监听来自客户端的连接请求，并对每个连接请求创建一个新的线程进行处理：

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

public class Server {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(9999);
        System.out.println("Server is listening on port 9999");
        
        while (true) {
            Socket socket = serverSocket.accept();
            System.out.println("New client connected");

            ClientHandler clientHandler = new ClientHandler(socket);
            clientHandler.start();
        }
    }

    private static class ClientHandler extends Thread {
        private final Socket clientSocket;
        private final BufferedReader in;
        private final PrintWriter out;

        public ClientHandler(Socket socket) throws IOException {
            this.clientSocket = socket;
            in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            out = new PrintWriter(clientSocket.getOutputStream(), true);
        }

        @Override
        public void run() {
            try {
                String request, response;
                int count = 0;

                while (count < 3) {
                    request = in.readLine();
                    System.out.println("Received from client: " + request);
                    response = "Response to " + request;
                    out.println(response);
                    count++;
                }

                clientSocket.close();
                System.out.println("Client disconnected");
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

然后是客户端的代码，它将连接到服务器并发送三个请求，每次请求后等待服务器的响应：

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

public class Client {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket("localhost", 9999);
        System.out.println("Connected to server");

        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        PrintWriter out = new PrintWriter(socket.getOutputStream(), true);

        String request, response;

        for (int i = 0; i < 3; i++) {
            request = "Request " + (i+1);
            out.println(request);
            response = in.readLine();
            System.out.println("Received from server: " + response);
        }

        socket.close();
        System.out.println("Connection closed");
    }
}

以上就是一个简单的Java代码示例，实现了客户端和服务器之间的通信，客户端向服务器发送三次请求，并接收服务器的响应。