使用FlowLayoutPanel.Controls.Clear 清除了FlowLayoutPanel上的所有控件。但是上面的控件使用AddHandler绑定了自定义事件。我该在执行Clear之前。如何先RemoveHandler上面的自定义事件，以防止内存泄露。

Question

使用FlowLayoutPanel.Controls.Clear  清除了FlowLayoutPanel上的所有控件。但是上面的控件使用AddHandler绑定了自定义事件。我该在执行Clear之前。如何先RemoveHandler上面的自定义事件，以防止内存泄露。Thanks!

Answer 1

您好

使用 FlowLayoutPanel.Controls.Clear 後，假如有將控件進行釋放，則不用特別去處理绑定了自定义事件

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Answer 2

这是真的吗？资料显示AddHandler和RemoveHandler需要成对使用。否则可能会造成内存泄露。

Answer 3

Clear 方法不会从内存中移除控件句柄。 Dispose 方法才能避免内存泄漏。

Answer 4

Hi ， 你可以用反射获取其handler

    Private Function GetEventHandler(ByVal ctrl As Control, ByVal eventname As String) As [Delegate]
        Dim propInfo As System.Reflection.PropertyInfo = GetType(System.ComponentModel.Component).GetProperty("Events", Reflection.BindingFlags.NonPublic Or Reflection.BindingFlags.Instance Or Reflection.BindingFlags.Static)
        Dim handlerList As System.ComponentModel.EventHandlerList = CType(propInfo.GetValue(ctrl, Nothing), System.ComponentModel.EventHandlerList)
        Dim controlEventInfo As System.Reflection.FieldInfo = GetType(Control).GetField(eventname, Reflection.BindingFlags.NonPublic Or Reflection.BindingFlags.Static)

        If controlEventInfo Is Nothing Then
            Throw New ArgumentException("Specified event does not exist.")
        End If

        Dim eventKey As Object = controlEventInfo.GetValue(ctrl)
        Dim EventHandlerDelegate As [Delegate] = handlerList.Item(eventKey)
        Return EventHandlerDelegate
    End Function

希望有用. 

---

Mike Feng
MSDN Community Support | Feedback to us
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

Answer 5

Hi ， 你可以用反射获取其handler

    Private Function GetEventHandler(ByVal ctrl As Control, ByVal eventname As String) As [Delegate]
        Dim propInfo As System.Reflection.PropertyInfo = GetType(System.ComponentModel.Component).GetProperty("Events", Reflection.BindingFlags.NonPublic Or Reflection.BindingFlags.Instance Or Reflection.BindingFlags.Static)
        Dim handlerList As System.ComponentModel.EventHandlerList = CType(propInfo.GetValue(ctrl, Nothing), System.ComponentModel.EventHandlerList)
        Dim controlEventInfo As System.Reflection.FieldInfo = GetType(Control).GetField(eventname, Reflection.BindingFlags.NonPublic Or Reflection.BindingFlags.Static)

        If controlEventInfo Is Nothing Then
            Throw New ArgumentException("Specified event does not exist.")
        End If

        Dim eventKey As Object = controlEventInfo.GetValue(ctrl)
        Dim EventHandlerDelegate As [Delegate] = handlerList.Item(eventKey)
        Return EventHandlerDelegate
    End Function

希望有用. 

---

Mike Feng
MSDN Community Support | Feedback to us
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

很好的方法。谢谢。我现在的做法:定义一个List字段保存了每个变量。然后枚举list字段变量清除绑定。

Answer 6

使用FlowLayoutPanel.Controls.Clear  清除了FlowLayoutPanel上的所有控件。但是上面的控件使用AddHandler绑定了自定义事件。我该在执行Clear之前。如何先RemoveHandler上面的自定义事件，以防止内存泄露。Thanks!

Answer 7

Hi ， 你可以用反射获取其handler

    Private Function GetEventHandler(ByVal ctrl As Control, ByVal eventname As String) As [Delegate]
        Dim propInfo As System.Reflection.PropertyInfo = GetType(System.ComponentModel.Component).GetProperty("Events", Reflection.BindingFlags.NonPublic Or Reflection.BindingFlags.Instance Or Reflection.BindingFlags.Static)
        Dim handlerList As System.ComponentModel.EventHandlerList = CType(propInfo.GetValue(ctrl, Nothing), System.ComponentModel.EventHandlerList)
        Dim controlEventInfo As System.Reflection.FieldInfo = GetType(Control).GetField(eventname, Reflection.BindingFlags.NonPublic Or Reflection.BindingFlags.Static)

        If controlEventInfo Is Nothing Then
            Throw New ArgumentException("Specified event does not exist.")
        End If

        Dim eventKey As Object = controlEventInfo.GetValue(ctrl)
        Dim EventHandlerDelegate As [Delegate] = handlerList.Item(eventKey)
        Return EventHandlerDelegate
    End Function

希望有用. 

---

Mike Feng
MSDN Community Support | Feedback to us
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

很好的方法。谢谢。我现在的做法:定义一个List字段保存了每个变量。然后枚举list字段变量清除绑定。

Answer 8

Hi ， 你可以用反射获取其handler

    Private Function GetEventHandler(ByVal ctrl As Control, ByVal eventname As String) As [Delegate]
        Dim propInfo As System.Reflection.PropertyInfo = GetType(System.ComponentModel.Component).GetProperty("Events", Reflection.BindingFlags.NonPublic Or Reflection.BindingFlags.Instance Or Reflection.BindingFlags.Static)
        Dim handlerList As System.ComponentModel.EventHandlerList = CType(propInfo.GetValue(ctrl, Nothing), System.ComponentModel.EventHandlerList)
        Dim controlEventInfo As System.Reflection.FieldInfo = GetType(Control).GetField(eventname, Reflection.BindingFlags.NonPublic Or Reflection.BindingFlags.Static)

        If controlEventInfo Is Nothing Then
            Throw New ArgumentException("Specified event does not exist.")
        End If

        Dim eventKey As Object = controlEventInfo.GetValue(ctrl)
        Dim EventHandlerDelegate As [Delegate] = handlerList.Item(eventKey)
        Return EventHandlerDelegate
    End Function

希望有用. 

---

Mike Feng
MSDN Community Support | Feedback to us
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

很好的方法。谢谢。我现在的做法:定义一个List字段保存了每个变量。然后枚举list字段变量清除绑定。