WinForms：如何以编程方式触发事件处理程序？

I want to programmatically invoke an event handler for a control. For example:

我想以编程方式调用控件的事件处理程序。例如:

DateTimePicker dtpLastConsummated;

I want to trigger the TextChanged event handler for the dtpLastConsummated, how can i do it?

我想为dtpLastConsummated触发TextChanged事件处理程序,我该怎么办呢?

In other languages I would call something akin to:

在其他语言中,我会称之为类似于:

dtpLastConsummated.TextChanged(this, new EventArgs());

but in .NET you can have multiple event handlers:

但在.NET中,您可以拥有多个事件处理程序:

dtpLastConsummated.Click +=new EventHandler(dtpLastConsummated_TextChanged);
dtpLastConsummated.Click +=new EventHandler(dtpLastConsummated_AnotherHandler);
dtpLastConsummated.Click +=new EventHandler(dtpLastConsummated_MoreHandlers);
...
dtpLastConsummated.Click +=new EventHandler(dtpLastConsummated_Nminus1);

so you need a way to trigger all the attached event handlers.

所以你需要一种方法来触发所有附加的事件处理程序。

Answer

The following code will fire the event:

以下代码将触发事件:

Toolkit.FireEvent(dtpLastConsummated, "TextChanged", new EventArgs());

And here's the code of the static toolkit function:

这是静态工具包函数的代码:

/// <summary>
/// Programatically fire an event handler of an object
/// </summary>
/// <param name="targetObject"></param>
/// <param name="eventName"></param>
/// <param name="e"></param>
public static void FireEvent(Object targetObject, string eventName, EventArgs e)
{
   /*
    * By convention event handlers are internally called by a protected
    * method called OnEventName
    * e.g.
    *     public event TextChanged
    * is triggered by
    *     protected void OnTextChanged
    * 
    * If the object didn't create an OnXxxx protected method,
    * then you're screwed. But your alternative was over override
    * the method and call it - so you'd be screwed the other way too.
    */

   //Event thrower method name //e.g. OnTextChanged
   String methodName = "On" + eventName;

   MethodInfo mi = targetObject.GetType().GetMethod(
         methodName, 
         BindingFlags.Instance | BindingFlags.NonPublic);

   if (mi == null)
      throw new ArgumentException("Cannot find event thrower named "+methodName);

   mi.Invoke(targetObject, new object[] { e });
}

Note: I'm not creating a subclass of every control in the .NET framework, and every 3rd party control, and convincing an enterprise worth of developers to retrofit every form to use my custom controls.

注意:我不是在.NET框架中创建每个控件的子类,而是每个第三方控件,并说服企业值得开发人员改进每个表单以使用我的自定义控件。

4 个解决方案

#1

3 suggestions to fire the TextChanged Event:

触发TextChanged事件的3条建议:

Manually change the text:

手动更改文字:

        string s = dateTimePicker1.Text;
        dateTimePicker1.Text = String.Empty;
        dateTimePicker1.Text = s;

Inherit from DateTimePicker and create a new method that exposes / calls DateTimePicker's protected OnTextChanged

从DateTimePicker继承并创建一个公开/调用DateTimePicker的受保护OnTextChanged的新方法

public class MyDateTimePicker : DateTimePicker
{
    public void OnTextChanged(EventArgs e)
    {
        base.OnTextChanged(e);
    }
}

If you don't like OOP and want to break encapsulation, you can access the protected OnTextChanged method through reflection:

如果您不喜欢OOP并希望打破封装,可以通过反射访问受保护的OnTextChanged方法:

        MethodInfo onTextChanged = dateTimePicker1.GetType().GetMethod("OnTextChanged", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
        onTextChanged.Invoke(dateTimePicker1, new object[] { new EventArgs() });

#2

Button in Windows Forms is a special case, because it has a PerformClick method to do exactly what you're talking about. For other events in other controls, though, there's really nothing similar.

Windows窗体中的按钮是一种特殊情况,因为它有一个PerformClick方法来完成您正在谈论的内容。但是,对于其他控件中的其他事件,实际上并没有什么相似之处。

#3

You can inherit from that class and create a new method that calls the protected OnSomeEvent() method.

您可以从该类继承并创建一个调用受保护的OnSomeEvent()方法的新方法。

class MyButton : Button
{
    public void CauseClick()
    {
        this.OnClick();
    }
}

As Matt pointed out, you can use PerformClick() for this specific example. However, most events don't have corresponding public functions to trigger them.

正如Matt所指出的,你可以使用PerformClick()来实现这个特定的例子。但是,大多数事件没有相应的公共函数来触发它们。

#4

Following code helped me to fire event

以下代码帮助我解雇了事件

ddlTopic_SelectedIndexChanged(this, new EventArgs());

Actual Event

private void ddlTopic_SelectedIndexChanged(object sender, EventArgs e)
{
   // do something
}

#1