编写数据接收类ReceiveThread，该类实现了Runnable接口，重写run()方法实现不断接受客户端发送数据的功能；编写数据发送类SendThread，该类同样实现了SendThread接口，重写run()方法实现通过键盘录入数据，将数据向接收端发送的功能。

下面是ReceiveThread和SendThread的代码示例：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;

public class ReceiveThread implements Runnable {
    private Socket socket;

    public ReceiveThread(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            String message;
            while ((message = reader.readLine()) != null) {
                System.out.println("Received message: " + message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

public class SendThread implements Runnable {
    private Socket socket;

    public SendThread(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        try {
            PrintWriter writer = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()), true);
            Scanner scanner = new Scanner(System.in);
            String message;
            while ((message = scanner.nextLine()) != null) {
                writer.println(message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

以上代码实现了客户端发送和接收数据的功能，需要在客户端的主函数中创建并启动这两个线程。