检查事件是否至少被触发过一次

本文关键字:一次 是否 事件 检查 | 更新日期: 2023-09-27 17:50:57

我正在跟踪一个事件是否像这样被触发:

bool IsFormLoaded;
private void Form1_Load(object sender, EventArgs e)
{
    //Do stuff
    IsFormLoaded = true;
}
private void button1_Click(object sender, EventArgs e)
{
    //Do stuff
}

但是对于许多事件这样做并不优雅,所以我想要一个解决方案,让我检查是否有像这样的事件被触发:

bool IsFormLoaded = IsEventFired(Form1_Loaded);
bool IsButton1Clicked = IsEventFired(Button1_Click);

检查事件是否至少被触发过一次

您正在使用设计器处理事件。例如,您可以在构造函数中这样做:

this.Load += delegate { IsFormLoaded = true; };
button1.Click += delegate { IsButton1Clicked = true; };

在我看来它更优雅:)

有趣的问题,在我看来好像你不想一遍又一遍地写。这就是为什么我宁愿使用单一的通用组件,而不是散列集或类似的东西。另外,由于表单实现通常是基于线程的,所以我使用了并发字典。

这个解决方案可以通过几种不同的方式进行改进;最明显的是使处理更通用,并且缺少0参数处理程序。为了通关,我尽量简化了。也许过几天我可能会在我的博客上发布一些更完整的东西;如果我有,我会在这里分享信息。

我的解决方案有两部分:(1)一个泛型钩子类和(2)窗体中的实现。目前的解决方案是懒惰的,例如,我把事件处理程序放在队列的末尾,而不是前面。你应该能够通过使用GetInvocationList或类似的东西来修复这个问题。

泛型钩子类基本上钩子事件并跟踪事件是否被调用:

public class EventHooks
{
    private class EventHooksEquality : IEqualityComparer<Tuple<string, object>>
    {
        public bool Equals(Tuple<string, object> x, Tuple<string, object> y)
        {
            return x.Item1.Equals(y.Item1) && object.ReferenceEquals(x.Item2, y.Item2);
        }
        public int GetHashCode(Tuple<string, object> obj)
        {
            return obj.Item1.GetHashCode();
        }
    }
    private ConcurrentDictionary<Tuple<string, object>, bool> called =
        new ConcurrentDictionary<Tuple<string, object>, bool>(new EventHooksEquality());
    private abstract class BaseHookHandler
    {
        protected BaseHookHandler(object container, string eventName, EventHooks hooks)
        {
            this.hooks = hooks;
            this.container = container;
            this.eventName = eventName;
        }
        protected string eventName;
        protected object container;
        protected EventHooks hooks;
    }
    private class HookHandler<T1> : BaseHookHandler
    {
        public HookHandler(object container, string eventName, EventHooks hooks)
            : base(container, eventName, hooks)
        {
        }
        public void Handle(T1 t1)
        {
            hooks.called.TryAdd(new Tuple<string, object>(eventName, container), true);
        }
    }
    private class HookHandler<T1, T2> : BaseHookHandler
    {
        public HookHandler(object container, string eventName, EventHooks hooks)
            : base(container, eventName, hooks)
        {
        }
        public void Handle(T1 t1, T2 t2)
        {
            hooks.called.TryAdd(new Tuple<string, object>(eventName, container), true);
        }
    }
    // add more handlers here...
    public void HookAll(object obj)
    {
        foreach (var eventHandler in obj.GetType().GetEvents()) 
        {
            Hook(obj, eventHandler.Name);
        }
    }
    public void Hook(object obj, string eventHandler)
    {
        if (obj == null)
        {
            throw new Exception("You have to initialize the object before hooking events.");
        }
        // Create a handler with the right signature
        var field = obj.GetType().GetEvent(eventHandler);
        var delegateInvoke = field.EventHandlerType.GetMethod("Invoke");
        Type[] parameterTypes = delegateInvoke.GetParameters().Select((a) => (a.ParameterType)).ToArray();
        // Select the handler with the correct number of parameters
        var genericHandler = Type.GetType(GetType().FullName + "+HookHandler`" + parameterTypes.Length);
        var handlerType = genericHandler.MakeGenericType(parameterTypes);
        var handlerObject = Activator.CreateInstance(handlerType, obj, eventHandler, this);
        var handler = handlerType.GetMethod("Handle");
        // Create a delegate
        var del = Delegate.CreateDelegate(field.EventHandlerType, handlerObject, handler);
        // Add the handler to the event itself
        field.AddEventHandler(obj, del);
    }
    public bool IsCalled(object obj, string eventHandler)
    {
        return called.ContainsKey(new Tuple<string, object>(eventHandler, obj));
    }
}

在类中的使用方法如下(示例):

   public Form1()
    {
        InitializeComponent();
        hooks.HookAll(this);
        // or something like: hooks.Hook(this, "Load");
        hooks.Hook(button1, "Click");
    }
    private EventHooks hooks = new EventHooks();
    private void Form1_Load(object sender, EventArgs e)
    {
    }
    private void button1_Click(object sender, EventArgs e)
    {
        this.textBox1.Text = 
            string.Format("Load: {0}'r'nClick: {1}'r'nButton click: {2}'r'n",
            hooks.IsCalled(this, "Load"),
            hooks.IsCalled(this, "Click"),
            hooks.IsCalled(button1, "Click"));
    }

编写自己的Base Form(派生自Windows.Forms.Form),并覆盖事件触发方法来捕获事件是否被触发。通过拥有一个基类,您将能够在所有表单中重用您的事件监视逻辑。

这里有一些您可以使用的示例代码。我在这里只使用了Loaded事件。对于想要监视的所有事件,都必须这样做。除了使用常量,还可以使用enum。希望能有所帮助

        const string OnLoadFired = "OnLoadFired";
        const string OnShownFired = "OnShownFired";
        List<string> eventsFired = new List<string>();
        protected override void OnLoad(EventArgs e)
        {
            if(!eventsFired.Contains(OnLoadFired))
            {
                eventsFired.Add(OnLoadFired);
            }
            base.OnLoad(e);
        }
        public bool IsEventFired(string eventName)
        {
            return eventsFired.Contains(eventName);
        }

与Dhawalk的回答类似。在我写这篇文章之前,我没有看到那个答案。

        private HashSet<string> events = new HashSet<string>();
        private void IsLoaded(object sender, RoutedEventArgs e)
        {
            // check
            System.Diagnostics.Debug.WriteLine(CheckEvents("IsLoaded", true).ToString());
            // add
            System.Diagnostics.Debug.WriteLine(CheckEvents("IsLoaded", false).ToString());
            // check
            System.Diagnostics.Debug.WriteLine(CheckEvents("IsLoaded", true).ToString());
        }
        private bool CheckEvents(string Event, bool CheckAdd)
        {
            // CheckAdd True to check
            // CheckAdd Fasle to add
            bool result = events.Contains(Event);
            if (!result && !CheckAdd) events.Add(Event);
            return result;
        }