用java实现一个聊天室，要求： 服务器端：一个线程专门发送消息，一个线程专门接收消息。 客户端：一个线程专门发送消息，一个线程专门接收消息。

以下是用Java实现一个简单的聊天室的示例代码，其中包含一个服务器端和客户端，每个端口分别有一个线程接收消息和一个线程发送消息：

服务器端代码：

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

public class Server {
    public static void main(String[] args) {
        try {
            // 创建服务器套接字，绑定端口
            ServerSocket serverSocket = new ServerSocket(8888);
            System.out.println("Server started.");
            while (true) {
                // 等待客户端连接
                Socket clientSocket = serverSocket.accept();
                System.out.println("Client connected.");

                // 创建接收和发送消息的线程
                Thread receiveThread = new Thread(new ReceiveMessage(clientSocket));
                Thread sendThread = new Thread(new SendMessage(clientSocket));
                receiveThread.start();
                sendThread.start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

class ReceiveMessage implements Runnable {
    private BufferedReader reader;
    private Socket socket;

    public ReceiveMessage(Socket socket) {
        this.socket = socket;
        try {
            // 初始化输入流
            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        try {
            while (true) {
                // 读取客户端发送的消息
                String message = reader.readLine();
                System.out.println(message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

class SendMessage implements Runnable {
    private PrintWriter writer;
    private Socket socket;

    public SendMessage(Socket socket) {
        this.socket = socket;
        try {
            // 初始化输出流
            writer = new PrintWriter(socket.getOutputStream(), true);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        try {
            BufferedReader consoleReader = new BufferedReader(new InputStreamReader(System.in));
            while (true) {
                // 读取控制台输入的消息，并发送给客户端
                String message = consoleReader.readLine();
                writer.println(message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

客户端代码：

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

public class Client {
    public static void main(String[] args) {
        try {
            // 连接服务器
            Socket socket = new Socket("localhost", 8888);
            System.out.println("Connected to server.");

            // 创建接收和发送消息的线程
            Thread receiveThread = new Thread(new ReceiveMessage(socket));
            Thread sendThread = new Thread(new SendMessage(socket));
            receiveThread.start();
            sendThread.start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

class ReceiveMessage implements Runnable {
    private BufferedReader reader;
    private Socket socket;

    public ReceiveMessage(Socket socket) {
        this.socket = socket;
        try {
            // 初始化输入流
            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        try {
            while (true) {
                // 读取服务器发送的消息
                String message = reader.readLine();
                System.out.println(message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

class SendMessage implements Runnable {
    private PrintWriter writer;
    private Socket socket;

    public SendMessage(Socket socket) {
        this.socket = socket;
        try {
            // 初始化输出流
            writer = new PrintWriter(socket.getOutputStream(), true);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        try {
            BufferedReader consoleReader = new BufferedReader(new InputStreamReader(System.in));
            while (true) {
                // 读取控制台输入的消息，并发送给服务器
                String message = consoleReader.readLine();
                writer.println(message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

以上代码仅为示例，可能存在一些问题，可以根据实际需求进行修改和优化。