動態調用對象事件

對某個控制項的事件進行編程；如，需要將當前運行期的按鈕替換掉，並且保留它的原始事件引用；方法如下：

 

 測試代碼

 看不到圖的請直接copy code

 

代碼

        private void button1_Click(object sender, EventArgs e)
        {
            MessageBox.Show("click by " + ((Button)sender).Name);
        }

        public void button2_Click(object sender, EventArgs e)
        {
            //調用button1 的click事件，並傳遞參數
            CalleventRaiseEvent(button1, "Click", button1, null);
        }

        private void button3_Click(object sender, EventArgs e)
        {
            //構造個新的按鈕
            var btn3 = new Button { Name = "btnTest_createNew", Text = "新按鈕", Parent = this,
                Left = button1.Left + button1.Width + 10, Top = button1.Top, Visible = true };
            //btn3.Click += (s, a) => CalleventRaiseEvent(button1, "Click", button1, null);
            //將舊按鈕事件放到新按鈕上去
            ReplaceEvent(button1, btn3, "Click");
            //刪除舊按鈕
            button1.Dispose();
            button1 = null;
        }
        /// <summary>
        /// 替換事件到控制項
        /// 必須保證 EventHandler 類型一致，否則會失敗
        /// </summary>
        /// <param name="sourceControl">原控制項</param>
        /// <param name="destControl">目標控制項</param>
        /// <param name="eventName">事件明</param>
        public void ReplaceEvent(Control sourceControl, Control destControl, string eventName)
        {
            if (sourceControl == null || destControl == null || string.IsNullOrEmpty(eventName))
                throw new NullReferenceException();

            Type type = sourceControl.GetType();
            PropertyInfo propertyInfo = type.GetProperty("Events", BindingFlags.Instance | BindingFlags.NonPublic);
            var eventHandlerList = (EventHandlerList)propertyInfo.GetValue(sourceControl, null);
            FieldInfo fieldInfo = (typeof(Control)).GetField("Event" + eventName, BindingFlags.Static | BindingFlags.NonPublic);
            Delegate d = eventHandlerList[fieldInfo.GetValue(null)];
            if (d != null)
            {
                foreach (Delegate di in d.GetInvocationList())
                    destControl.GetType().GetEvent(eventName).AddEventHandler(destControl, d);
            }
            else
                throw new InvalidCastException("無效的事件轉換!");
        }
        /// <summary>
        /// 呼叫事件方法
        /// </summary>
        /// <param name="control">目標控制項</param>
        /// <param name="eventName">方法名</param>
        /// <param name="args">方法參數</param>
        public void CalleventRaiseEvent(Control control, string eventName, params object[] args)
        {
            if (control == null || string.IsNullOrEmpty(eventName))
                throw new NullReferenceException();

            Type type = control.GetType();

            EventInfo eventInfo = type.GetEvent(eventName);
            MethodInfo methodInfo = eventInfo.GetRaiseMethod();
            if (methodInfo != null)
                methodInfo.Invoke(this, args);
            else
            {
                PropertyInfo propertyInfo = type.GetProperty("Events", BindingFlags.Instance | BindingFlags.NonPublic);
                var eventHandlerList = (EventHandlerList)propertyInfo.GetValue(control, null);
                FieldInfo fieldInfo = (typeof(Control)).GetField("Event" + eventName, BindingFlags.Static | BindingFlags.NonPublic);
                Delegate d = eventHandlerList[fieldInfo.GetValue(null)];
                if (d != null)
                {
                    foreach (Delegate di in d.GetInvocationList())
                        di.DynamicInvoke(args);
                }
                else
                    throw new NullReferenceException("無效的事件激發!");
            }
        }