调用和事件时如何传递其他参数VB.net [英] How to Pass Additional Parameters When Calling and Event VB.net

问题描述

公开事件DocumentCompleted作为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
/ pre>

在触发DocumentCompleted事件时，如何通过homeTeam和guestTeam。
我想把上面的值放在Dostuff方法里面。

请帮助。

解决方案

首先，你不能把它挂在无处的中间位置：

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

AddHandler 可能需要在一些初始化方法中，这可能在 Sub New ， InitializeComponent 之后，或 Form_Load 内，或一旦你期望它被触发（在特定事件之后）。请注意，您正在使用默认事件类型的本机.NET组件的默认事件。在这种情况下，触发时，您不能直接使用它已经提供的任何东西。请参阅 MSDN上的WebBrowser.DocumentCompleted事件

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

 公共类Form1 
 Sub New（）
'设计师。 
 InitializeComponent（）
 
 Dim浏览器作为新的MyWebBrowser 
 AddHandler browser.MyDocumentCompleted，AddressOf DoStuff 
 End Sub 
 
 Private Sub DoStuff（ByVal发件人As Object，ByVal e As MyWebBrowserDocumentCompletedArgs）
 Dim guestTeam As String = e.GuestTeam'guest team 
 Dim homeTeam As String = e.HomeTeam'和主队都可以访问
'，所以你可以对它们进行一些处理
 End Sub 
 
公共类MyWebBrowserDocumentCompletedArgs：Inherits WebBrowserDocumentCompletedEventArgs 
 Dim _homeTeam As String 
 Dim _guestTeam As String 
公共ReadOnly属性HomeTeam 
获取
返回_homeTeam 
结束获取
结束属性
公共ReadOnly属性GuestTeam 
获取
返回_guestTeam 
结束获取
 End Property 
 
 Sub New（url As Uri，homeTeam As String，guestTeam As String）
 MyBase。 New（url）
 _homeTeam = homeTeam 
 _guestTeam = guestTeam 
 End Sub 
结束类
 
公共类MyWebBrowser：继承WebBrowser 
公共代理Sub MyWebBrowserDocumentCompletedEventHandler（e As MyWebBrowserDocumentCompletedArgs）
公共事件MyDocumentCompleted作为MyWebBrowserDocumentCompletedEventHandler 
 
受保护的覆盖Sub OnDocumentCompleted（e As System.Windows.Forms.WebBrowserDocumentCompletedEventArgs）
 MyBase.OnDocumentCompleted（e）
'homeTeam和guestTeam需要从当前的MyWebBrowser实例中提取，并进一步传递
 RaiseEvent MyDocumentCompleted（New MyWebBrowserDocumentCompletedArgs（e.Url，homeTeam，guestTeam））
 End Sub 
结束类
结束类
  

如果您的项目相对较小，您可以确实有那些作为全局变量，如@Vlad在评论中建议的。

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

How can I pass the homeTeam and guestTeam when firing the DocumentCompleted event. I want to ge the above to values to inside the Dostuff method.

Please help.

解决方案

First of all, you cannot have this hanging in the middle of nowhere:

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

AddHandler probably needs to be in some Initialize method, which could be inside Sub New, after InitializeComponent, or inside Form_Load, or as soon as you expect it to be triggered (after a specific event). Notice here that you are using a default event of a native .NET component, with a default event type. In this case you cannot directly consume anything other than what it already provides, when triggered. See WebBrowser.DocumentCompleted Event on MSDN.

You can, however, override all relevant classes and have your own MyWebBrowser control and your own event, with would contain additional properties. See below example:

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

If your project is relatively small, you can indeed have those as global variables, as @Vlad suggested in the comments.

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