Winform 使用事件回调机制

winform 中特别是子窗体向父窗体传递参数的时候，通常使用事件回调机制。

1.简单的事件回调:

1.1定义一个EventHub类

public static class EventBus
{
    // 定义事件
    public static event Action<string> MessagePublished;

    // 发布消息的方法
    public static void PublishMessage(string message)
    {
        MessagePublished?.Invoke(message);
    }
}

1.2 在需要使用的窗体类中写一个方法并调用

private void OnMessageReceived(string message)
{
    // 确保UI更新在主线程执行
    if (this.InvokeRequired)
    {
        this.Invoke(new Action<string>(OnMessageReceived), message);
        return;
    }
    //执行具体逻辑
}


 public MainForm()
 {
     InitializeComponent();
     // 订阅事件
     EventBus.MessagePublished += OnMessageReceived;
 }

2.通用事件回调机制

2.1 定义一个EventBus类

public static class EventBus
{
    private static readonly Dictionary<Type, List<Delegate>> _eventHandlers = new Dictionary<Type, List<Delegate>>();

    // 发布事件
    public static void Publish<TEventArgs>(TEventArgs e) where TEventArgs : EventArgs
    {
        Type eventType = typeof(TEventArgs);
        if (_eventHandlers.ContainsKey(eventType))
        {
            foreach (Delegate handler in _eventHandlers[eventType].ToArray())
            {
                ((Action<TEventArgs>)handler)(e);
            }
        }
    }

    // 订阅事件
    public static void Subscribe<TEventArgs>(Action<TEventArgs> handler) where TEventArgs : EventArgs
    {
        Type eventType = typeof(TEventArgs);
        if (!_eventHandlers.ContainsKey(eventType))
        {
            _eventHandlers[eventType] = new List<Delegate>();
        }

        _eventHandlers[eventType].Add(handler);
    }

    // 取消订阅
    public static void Unsubscribe<TEventArgs>(Action<TEventArgs> handler) where TEventArgs : EventArgs
    {
        Type eventType = typeof(TEventArgs);
        if (_eventHandlers.ContainsKey(eventType))
        {
            _eventHandlers[eventType].Remove(handler);

            if (_eventHandlers[eventType].Count == 0)
            {
                _eventHandlers.Remove(eventType);
            }
        }
    }
}

// 通用事件参数基类
public class EventArgs<T> : EventArgs
{
    public EventArgs(T value)
    {
        Value = value;
    }

    public T Value { get; private set; }
}

// 特定类型的事件参数
public class StringEventArgs : EventArgs<string>
{
    public StringEventArgs(string value) : base(value)
    {
    }
}

public class IntEventArgs : EventArgs<int>
{
    public IntEventArgs(int value) : base(value)
    {
    }
}

// 自定义事件参数示例
public class UserLoginEventArgs : EventArgs
{
    public string Username { get; set; }
    public DateTime LoginTime { get; set; }

    public UserLoginEventArgs(string username)
    {
        Username = username;
        LoginTime = DateTime.Now;
    }
}

2.2是需要的窗体中使用，如主窗体

 public partial class MainForm : Form
 {
     public MainForm()
     {
         InitializeComponent();

         // 订阅事件
         EventBus.Subscribe<StringEventArgs>(OnStringEvent);
         EventBus.Subscribe<UserLoginEventArgs>(OnUserLogin);
     }


     private void OnStringEvent(StringEventArgs e)
     {
         // 确保在UI线程上更新控件
         if (InvokeRequired)
         {
             Invoke(new Action<StringEventArgs>(OnStringEvent), e);
             return;
         }

         lblStatus.Text = $"收到字符串事件: {e.Value}";
     }

     private void OnUserLogin(UserLoginEventArgs e)
     {
         if (InvokeRequired)
         {
             Invoke(new Action<UserLoginEventArgs>(OnUserLogin), e);
             return;
         }

         lblUserStatus.Text = $"用户 {e.Username} 于 {e.LoginTime} 登录";
     }

     private void btnPublishEvent_Click(object sender, EventArgs e)
     {
         var num = new Random().Next(0, 100);
         // 发布事件
         EventBus.Publish(new StringEventArgs(num.ToString()));
         EventBus.Publish(new UserLoginEventArgs("詹三"));
     }

     private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
     {
         // 取消订阅事件（重要：避免内存泄漏）
         EventBus.Unsubscribe<StringEventArgs>(OnStringEvent);
         EventBus.Unsubscribe<UserLoginEventArgs>(OnUserLogin);
     }
 }