Question

我们有一个Windows Forms应用程序实例化一个dll，并在该dll中实例化类。

修改

所以这个过程是这样的：

FORM＆gt; alpsClient（DLL）＆gt;类

我想从类中更新FORM上的backgroundWorker_ProgressChanged事件。

结束编辑

在类对象中完成工作可能需要一段时间。

我希望将某些类型的进度从课程传回给调用表单。

我想我需要使用事件。

但是我应该如何引用在后台工作者中启动该过程的表单。

以下是实例化dll对象的代码：

   Private Sub alpsManual_bgw_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles alpsManual_bgw.DoWork
    Try

        Dim arg As String = CStr(e.Argument)
        objDoc = New alpsClient

        '* Set variables and start
        ' CUT ...

        If fromArchive Then
            '********************************************
            '* Manual Settings                          *
            '********************************************
             ' SET PROPERTIES
             ... CUT for brevity
            '********************************************
        End If

        objDoc.docMap()
        '* Wait until isComplete before starting next
        Do
            System.Threading.Thread.Sleep(1000)
        Loop Until objDoc.isComplete

    Catch ex As Exception

以下是将在alpsClient.docMap：

中实例化类的代码

Dim objControl As Object = Nothing

Select Case docRef
    Case "YL0PF"                    'Arrears Advice
        objControl = New YL0PF
    Case "YL2PF"                    'Arrears with Additional Interest
        objControl = New YL2PF

... etc

然后：

objControl.dbConn = masterDB
objControl.docRef = docRef
objControl.table2Format = table2Format
objControl.newAddressFormat = newAddressFormat
objControl.dteinp = runDate
' Start
docMap = ""
If Not objControl.Controller() Then docMap = "Errors"

并且它在objControl引用的类中，我想将进度消息发送回调用表单...可能使用事件。

或者这是一个非常糟糕的主意？

Answer 1

您可以确保所有控件类都从公共基类继承，例如：

Public MustInherit Class ControlBase
   Protected Sub New()
   End Sub

   Public Event ProgressEvent As EventHandler<Of ProgressEventArgs>

   Protected Sub RaiseProgressEvent(current As Integer, maximum as Integer)
       RaiseEvent ProgressEvent(Me, New ProgressEventArgs(current, maximum)
   End Sub

End Class

Public Class ProgressEventArgs : Inherits EventArgs
   Private _current as Integer
   Private _maximum as Integer

   Public Sub New(current As Integer, maximum as Integer)
      _current = current
      _maximum = maximum
   End Sub

   Public ReadOnly Property Current() As Integer
      Get
         Return _current
      End Get
   End Property

   Public ReadOnly Property Maximum() As Integer
      Get
         Return _maximum
      End Get
   End Property
End Class

然后你的每个YL0PF，YL2PF等等都继承自这个类并调用RaiseProgressEvent。

当你教导课程时，做这样的事情......

Dim objControl As ControlBase = Nothing

Select Case docRef
    Case "YL0PF"                    'Arrears Advice
        objControl = New YL0PF
    Case "YL2PF"                    'Arrears with Additional Interest
        objControl = New YL2PF

... etc
End Select

AddHandler objControl.ProgressEvent, AddressOf OnProgressEvent
objControl.DoSomething()  ' <- lengthy process will raise ProgressEvent
....

Sub OnProgressEvent(sender as Object, e As ProgressEventArgs)
  ' Update your progress control - pay attention to "simon at rcl"'s comment above
  ' about making sure this is done on the GUI thread.  You will have to use Invoke 
  ' if the event will be fired from another thread.

  ' OP mentioned in a comment that they are using a BackgroundWorker so the
  ' ProgressEvent will be called in a background thread which can't change the
  ' UI.  So you would call its ReportProgress which will in turn raise its own
  ' ProgressChanged event but on the UI thread.
  backgroundWorker1.ReportProgress(CInt(e.Current / e.Maximum * 100))
End Sub 

Private Sub backgroundWorker1_ProgressChanged( _
            sender As Object, e As ProgressChangedEventArgs) _
            Handles backgroundWorker1.ProgressChanged
      ' This will be called on the UI thread, so we can update the ProgressBar
      Me.progressBar1.Value = e.ProgressPercentage
End Sub

将引用类中的信息传递回调用表单

1 个答案: