如何在调用VB.net时传递附加参数

Question

Public Event DocumentCompleted As WebBrowserDocumentCompletedEventHandler 

Dim arg() As Object = {homeTeam, guestTeam} 
     AddHandler browser.DocumentCompleted, New 
WebBrowserDocumentCompletedEventHandler(AddressOf DoStuff) 

Private Sub DoStuff(ByVal sender As Object, ByVal e As WebBrowserDocumentCompletedEventArgs) 

End Sub 

如何在发射DocumentCompleted事件时传递homeTeam和guestTeam。 我想将上面的值转换为Dostuff方法中的值。

请帮忙。

Answer 1

首先，你不能有这个挂在中间的地方：

Dim arg() As Object = {homeTeam, guestTeam} 
AddHandler browser.DocumentCompleted, 
      New WebBrowserDocumentCompletedEventHandler(AddressOf DoStuff) 

AddHandler可能需要在某些Initialize方法，这可能是内部Sub New，InitializeComponent后，或内部，或者只要你期望它被触发（特定事件之后）。请注意，您正在使用默认事件类型的本地.NET组件的默认事件。在这种情况下，触发时，您不能直接使用除已提供的内容之外的其他任何内容。请参阅WebBrowser.DocumentCompleted Event on MSDN。

但是，您可以覆盖所有相关的类，并拥有自己的MyWebBrowser控件和您自己的事件，并包含其他属性。见下面的例子：

Public Class Form1 
    Sub New() 
    ' This call is required by the designer. 
    InitializeComponent() 

    Dim browser As New MyWebBrowser 
    AddHandler browser.MyDocumentCompleted, AddressOf DoStuff 
    End Sub 

    Private Sub DoStuff(ByVal sender As Object, ByVal e As MyWebBrowserDocumentCompletedArgs) 
    Dim guestTeam As String = e.GuestTeam 'guest team 
    Dim homeTeam As String = e.HomeTeam 'and home team are both accessible 
    'so you can do some processing on them 
    End Sub 

    Public Class MyWebBrowserDocumentCompletedArgs : Inherits WebBrowserDocumentCompletedEventArgs 
    Dim _homeTeam As String 
    Dim _guestTeam As String 
    Public ReadOnly Property HomeTeam 
     Get 
     Return _homeTeam 
     End Get 
    End Property 
    Public ReadOnly Property GuestTeam 
     Get 
     Return _guestTeam 
     End Get 
    End Property 

    Sub New(url As Uri, homeTeam As String, guestTeam As String) 
     MyBase.New(url) 
     _homeTeam = homeTeam 
     _guestTeam = guestTeam 
    End Sub 
    End Class 

    Public Class MyWebBrowser : Inherits WebBrowser 
    Public Delegate Sub MyWebBrowserDocumentCompletedEventHandler(e As MyWebBrowserDocumentCompletedArgs) 
    Public Event MyDocumentCompleted As MyWebBrowserDocumentCompletedEventHandler 

    Protected Overrides Sub OnDocumentCompleted(e As System.Windows.Forms.WebBrowserDocumentCompletedEventArgs) 
     MyBase.OnDocumentCompleted(e) 
     'homeTeam and guestTeam need to be extracted from the current instance of MyWebBrowser, and passed further 
     RaiseEvent MyDocumentCompleted(New MyWebBrowserDocumentCompletedArgs(e.Url, "homeTeam", "guestTeam")) 
    End Sub 
    End Class 
End Class 

如果你的项目是比较小的，你确实可以有那些为全局变量，如@Vlad的意见建议。