diff --git a/CS3.1.cs b/CS3.1.cs
new file mode 100644
index 0000000..cbdd615
--- /dev/null
+++ b/CS3.1.cs
@@ -0,0 +1,251 @@
+using System;
+using System.Net.Sockets;
+using System.Text;
+using System.Text.Json;
+using System.Threading;
+using System.Windows.Forms;
+
+namespace ChatClient
+{
+    public partial class MainForm : Form
+    {
+        private TcpClient _client;
+        private NetworkStream _stream;
+        private Thread _receiveThread;
+        private bool _isConnected = false;
+        private string _username = "";
+
+        public MainForm()
+        {
+            InitializeComponent();
+            SetConnectionState(false);
+        }
+
+        private void SetConnectionState(bool connected)
+        {
+            _isConnected = connected;
+            btnConnect.Enabled = !connected;
+            btnDisconnect.Enabled = connected;
+            btnLogin.Enabled = connected;
+            btnRegister.Enabled = connected;
+            btnSend.Enabled = connected && _username != "";
+        }
+
+        private void btnConnect_Click(object sender, EventArgs e)
+        {
+            try
+            {
+                _client = new TcpClient();
+                _client.Connect("localhost", 8888);
+                _stream = _client.GetStream();
+                _isConnected = true;
+                
+                _receiveThread = new Thread(ReceiveMessages);
+                _receiveThread.IsBackground = true;
+                _receiveThread.Start();
+                
+                SetConnectionState(true);
+                AddMessage("系统", "已连接到服务器");
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show($"连接失败: {ex.Message}", "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
+            }
+        }
+
+        private void btnDisconnect_Click(object sender, EventArgs e)
+        {
+            Disconnect();
+        }
+
+        private void Disconnect()
+        {
+            if (_isConnected)
+            {
+                try
+                {
+                    _isConnected = false;
+                    _client?.Close();
+                    _stream?.Close();
+                    _receiveThread?.Join(1000);
+                }
+                catch { }
+                
+                SetConnectionState(false);
+                _username = "";
+                AddMessage("系统", "已断开连接");
+            }
+        }
+
+        private void btnLogin_Click(object sender, EventArgs e)
+        {
+            if (!_isConnected) return;
+            
+            var username = txtUsername.Text.Trim();
+            var password = txtPassword.Text;
+
+            if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
+            {
+                MessageBox.Show("用户名和密码不能为空", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+                return;
+            }
+
+            try
+            {
+                var loginData = new
+                {
+                    type = "login",
+                    username = username,
+                    password = password
+                };
+
+                var json = JsonSerializer.Serialize(loginData);
+                var buffer = Encoding.UTF8.GetBytes(json);
+                _stream.Write(buffer, 0, buffer.Length);
+
+                // 等待响应
+                var responseBuffer = new byte[1024];
+                var bytesRead = _stream.Read(responseBuffer, 0, responseBuffer.Length);
+                var responseJson = Encoding.UTF8.GetString(responseBuffer, 0, bytesRead);
+                var response = JsonSerializer.Deserialize<JsonElement>(responseJson);
+
+                if (response.TryGetProperty("status", out var status) && status.GetString() == "success")
+                {
+                    _username = username;
+                    SetConnectionState(true);
+                    AddMessage("系统", $"登录成功，欢迎 {username}");
+                }
+                else
+                {
+                    var message = response.TryGetProperty("message", out var msg) ? msg.GetString() : "登录失败";
+                    MessageBox.Show(message, "登录失败", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                }
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show($"登录时发生错误: {ex.Message}", "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                Disconnect();
+            }
+        }
+
+        private void btnRegister_Click(object sender, EventArgs e)
+        {
+            if (!_isConnected) return;
+            
+            var username = txtUsername.Text.Trim();
+            var password = txtPassword.Text;
+
+            if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
+            {
+                MessageBox.Show("用户名和密码不能为空", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+                return;
+            }
+
+            try
+            {
+                var registerData = new
+                {
+                    type = "register",
+                    username = username,
+                    password = password
+                };
+
+                var json = JsonSerializer.Serialize(registerData);
+                var buffer = Encoding.UTF8.GetBytes(json);
+                _stream.Write(buffer, 0, buffer.Length);
+
+                // 等待响应
+                var responseBuffer = new byte[1024];
+                var bytesRead = _stream.Read(responseBuffer, 0, responseBuffer.Length);
+                var responseJson = Encoding.UTF8.GetString(responseBuffer, 0, bytesRead);
+                var response = JsonSerializer.Deserialize<JsonElement>(responseJson);
+
+                if (response.TryGetProperty("success", out var success) && success.GetBoolean())
+                {
+                    MessageBox.Show("账号注册成功，请登录", "注册成功", MessageBoxButtons.OK, MessageBoxIcon.Information);
+                }
+                else
+                {
+                    var message = response.TryGetProperty("message", out var msg) ? msg.GetString() : "注册失败";
+                    MessageBox.Show(message, "注册失败", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                }
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show($"注册时发生错误: {ex.Message}", "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                Disconnect();
+            }
+        }
+
+        private void btnSend_Click(object sender, EventArgs e)
+        {
+            if (!_isConnected || string.IsNullOrEmpty(_username)) return;
+            
+            var message = txtMessage.Text.Trim();
+            if (string.IsNullOrEmpty(message)) return;
+
+            try
+            {
+                var chatData = new
+                {
+                    type = "chat",
+                    message = message
+                };
+
+                var json = JsonSerializer.Serialize(chatData);
+                var buffer = Encoding.UTF8.GetBytes(json);
+                _stream.Write(buffer, 0, buffer.Length);
+                
+                AddMessage(_username, message);
+                txtMessage.Clear();
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show($"发送消息失败: {ex.Message}", "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                Disconnect();
+            }
+        }
+
+        private void ReceiveMessages()
+        {
+            var buffer = new byte[1024];
+            
+            try
+            {
+                while (_isConnected && _client.Connected)
+                {
+                    var bytesRead = _stream.Read(buffer, 0, buffer.Length);
+                    if (bytesRead == 0) break;
+                    
+                    var messageJson = Encoding.UTF8.GetString(buffer, 0, bytesRead);
+                    var message = JsonSerializer.Deserialize<JsonElement>(messageJson);
+
+                    if (message.TryGetProperty("type", out var type))
+                    {
+                        var messageType = type.GetString();
+                        if (messageType == "chat")
+                        {
+                            var user = message.GetProperty("user").GetString();
+                            var msg = message.GetProperty("message").GetString();
+                            this.Invoke((MethodInvoker)delegate { AddMessage(user, msg); });
+                        }
+                    }
+                }
+            }
+            catch { }
+            
+            this.Invoke((MethodInvoker)Disconnect);
+        }
+
+        private void AddMessage(string user, string message)
+        {
+            txtChat.AppendText($"{user}: {message}{Environment.NewLine}");
+            txtChat.ScrollToCaret();
+        }
+
+        private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
+        {
+            Disconnect();
+        }
+    }
+}
\ No newline at end of file