C# 用反射动态绑定事件

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Reflection;
using System.Diagnostics;namespace WebApplication5
{
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
EventHandler clickHandler = delegate(object s, EventArgs x) {
var ctrl = s as WebControl;
Debug.Print(ctrl.ID);
}; var click = Button1.GetType().GetEvents().FirstOrDefault(ei => ei.Name.ToLower() == "click");
var handler = Delegate.CreateDelegate(clickHandler.GetType(), clickHandler.Method);
click.AddEventHandler(Button1, handler);
}
}
}

使用预定义委托：

public void registerUserActionLog(Control ctrl)
{
var click = ctrl.GetType().GetEvents().FirstOrDefault(ei => ei.Name.ToLower() == "click");
if (click != null)
{
var method = this.GetType().GetMethod("ctrl_Click");
var handler = Delegate.CreateDelegate(click.EventHandlerType, this, method);
click.AddEventHandler(ctrl, handler);
} foreach (Control c in ctrl.Controls)
{
registerUserActionLog(c);
}
} public void ctrl_Click(object sender, EventArgs e)
{
var ctrl = sender as WebControl;
OMSLogManager.UserActionLogger.log(this.GetType().Name + "\t" + ctrl.ID + ".Click");
}

动态调整事件处理程序的调用顺序：

public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
var method = this.GetType().GetMethod("ctrl_Click");
var click = Button1.GetType().GetEvents().FirstOrDefault(ei => ei.Name.ToLower() == "click");
var handler = Delegate.CreateDelegate(click.EventHandlerType, null, method);
var handlerList = new List<Delegate>(); PropertyInfo propertyInfo = Button1.GetType().GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance);
EventHandlerList eventHandlerList = propertyInfo.GetValue(Button1, new object[] { }) as EventHandlerList;
FieldInfo fieldInfo = typeof(Button).GetField("EventClick", BindingFlags.NonPublic | BindingFlags.Static);
if(fieldInfo == null)
fieldInfo = typeof(Button).GetField("Click", BindingFlags.NonPublic | BindingFlags.Static);
if (fieldInfo != null)
{
object eventKey = fieldInfo.GetValue(Button1);
var del = eventHandlerList[eventKey] as Delegate;
foreach (var h in del.GetInvocationList())
{
//preserve previous eventhandler
handlerList.Add(h); //remove previous eventhandler
click.RemoveEventHandler(Button1, h);
}
} //add new eventhandler
click.AddEventHandler(Button1, handler); //add previous eventhandler
foreach (var h in handlerList)
{
click.AddEventHandler(Button1, h);
}
} public void ctrl_Click(object sender, EventArgs e)
{ } protected void Button1_Click(object sender, EventArgs e)
{ }
}