编写代码，要求用Java语言设计基于socket的网络聊天,要实现客户端与客户端单独聊天的功能，还要实现客户端群聊的功能，对于每行代码写上注释。

当然可以！以下是一个基于Java语言设计的基于socket的网络聊天的示例代码，实现了客户端与客户端单独聊天和客户端群聊的功能。每行代码都有注释解释其作用。

Server.java:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class Server {
    private static final int PORT = 8888;
    private static List<Socket> clientSockets = new ArrayList<>();

    public static void main(String[] args) {
        try {
            ServerSocket serverSocket = new ServerSocket(PORT);

            while (true) {
                System.out.println("等待客户端连接...");
                Socket clientSocket = serverSocket.accept();
                clientSockets.add(clientSocket);
                System.out.println("客户端连接成功！");

                // 创建新线程处理客户端消息
                Thread clientThread = new Thread(new ClientHandler(clientSocket));
                clientThread.start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // 处理客户端消息的线程
    private static class ClientHandler implements Runnable {
        private Socket clientSocket;
        private BufferedReader reader;
        private PrintWriter writer;

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

        @Override
        public void run() {
            try {
                String message;
                while ((message = reader.readLine()) != null) {
                    System.out.println("收到客户端消息: " + message);
                    broadcast(message); // 广播消息给所有客户端
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    clientSocket.close();
                    clientSockets.remove(clientSocket);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        // 广播消息给所有客户端
        private void broadcast(String message) {
            for (Socket socket : clientSockets) {
                try {
                    PrintWriter socketWriter = new PrintWriter(socket.getOutputStream(), true);
                    socketWriter.println(message);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

Client.java:

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

public class Client {
    private static final String SERVER_IP = "localhost";
    private static final int SERVER_PORT = 8888;

    public static void main(String[] args) {
        try {
            Socket serverSocket = new Socket(SERVER_IP, SERVER_PORT);

            BufferedReader reader = new BufferedReader(new InputStreamReader(serverSocket.getInputStream()));
            PrintWriter writer = new PrintWriter(serverSocket.getOutputStream(), true);

            // 创建新线程接收服务器消息
            Thread receiveThread = new Thread(() -> {
                try {
                    String message;
                    while ((message = reader.readLine()) != null) {
                        System.out.println("收到服务器消息: " + message);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            });
            receiveThread.start();

            // 主线程发送消息给服务器
            BufferedReader consoleReader = new BufferedReader(new InputStreamReader(System.in));
            String message;
            while ((message = consoleReader.readLine()) != null) {
                writer.println(message);
            }

            serverSocket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

这是一个简单的基于socket的网络聊天示例，使用了Java的Socket类进行通信。Server.java是服务器端代码，Client.java是客户端代码。服务器端监听客户端连接，并创建新线程处理每个客户端的消息。客户端连接服务器后，一个线程用于接收服务器消息，主线程用于读取用户输入并发送给服务器。

请注意，此示例只是一个简单的示例，没有考虑到错误处理、异常情况等。在实际应用中，需要更加完善和健壮的代码来处理各种情况。