响应类实例列表中的事件

Question

我有一个.NET类InstrumentConnector，它具有一个事件StatusChanged。 我想创建此类的几个实例（每个类处理一个单独的文件），并在任何实例引发StatusChanged事件时做出响应。 我将如何在.NET中执行此操作？ 我是否要创建一个List（Of InstrumentConnector）或类似的IEnumerable？ 如何编写事件处理程序以响应特定实例的StatusChanged事件？

这是InstrumentConnector类和带有StatusChanged处理函数的模块：

Public Class InstrumentConnector

Private _inProcessDir As String
Private _doneDir As String

Private _dataFileName As String
Public ReadOnly Property DataFileName() As String
    Get
        Return _dataFileName
    End Get

End Property


Private WithEvents _processTimer As Timers.Timer

Private _fileStatus As Status
Public ReadOnly Property FileStatus() As Status
    Get
        Return _fileStatus
    End Get

End Property


Public Sub New(ByVal inProcessDirectory As String, ByVal doneDirectory As String)
    _inProcessDir = inProcessDirectory
    _doneDir = doneDirectory
    _fileStatus = Status.Waiting
End Sub

Public Sub New(ByVal inProcessDirectory As String)
    Me.New(inProcessDirectory, IO.Path.Combine(inProcessDirectory, "done"))
End Sub

Private Sub InitializeTimer()
    _processTimer = New Timers.Timer
    With _processTimer
        .Interval = 1000
    End With
End Sub

Public Sub Process(ByVal dataFileName As String)

    _dataFileName = IO.Path.GetFileName(dataFileName)

    InitializeTimer()

    _processTimer.Start()

End Sub

Private Sub _processTimer_Elapsed(ByVal sender As Object, ByVal e As System.Timers.ElapsedEventArgs) Handles _processTimer.Elapsed

    '1. Look for file in Done directory
    '2. Evaluate its approval status
    '3. If not completed change approval setting in file and move to InProcess directory

    If IsFileInProcessDirectory() = True Then
        MoveFileToDoneDirectory()
    Else
        If IsFileInDoneDirectory() = True Then
            If IsFileApproved() = True Then
                _fileStatus = Status.Accepted
                RaiseEvent StatusChanged(Nothing)
            Else
                If NeedsSecondAttempt() = True Then
                    MoveFileToProcessDirectory()
                Else
                    _fileStatus = Status.Rejected
                    RaiseEvent StatusChanged(Nothing)
                End If

            End If

        End If
    End If

End Sub

Private Sub MoveFileToDoneDirectory()

    Dim fileContents As String
    fileContents = My.Computer.FileSystem.ReadAllText(IO.Path.Combine(_inProcessDir, _dataFileName))

    If GetFileApprovalStatus() = True Then
        fileContents = String.Concat("9999", fileContents.Substring(4))
    End If

    My.Computer.FileSystem.WriteAllText(IO.Path.Combine(_doneDir, _dataFileName), fileContents, False)
    My.Computer.FileSystem.DeleteFile(IO.Path.Combine(_inProcessDir, _dataFileName))

End Sub

Private Function NeedsSecondAttempt() As Boolean
    Dim fileContents As String
    fileContents = My.Computer.FileSystem.ReadAllText(IO.Path.Combine(_doneDir, _dataFileName))

    If fileContents.StartsWith("9999") And fileContents.Substring(111, 1) = "1" Then
        Return False
    Else
        Return True
    End If

End Function

Private Sub MoveFileToProcessDirectory()

    Dim fileContents As String
    fileContents = My.Computer.FileSystem.ReadAllText(IO.Path.Combine(_doneDir, _dataFileName))

    fileContents = fileContents.Remove(111, 1).Insert(111, "1")
    My.Computer.FileSystem.WriteAllText(IO.Path.Combine(_doneDir, _dataFileName), fileContents, False)

    My.Computer.FileSystem.MoveFile(IO.Path.Combine(_doneDir, _dataFileName), IO.Path.Combine(_inProcessDir, _dataFileName))

End Sub

Private Function IsFileInDoneDirectory() As Boolean

    Dim fileExists As Boolean
    fileExists = My.Computer.FileSystem.FileExists(IO.Path.Combine(_doneDir, _dataFileName))

    Return fileExists

End Function

Private Function IsFileInProcessDirectory() As Boolean

    Dim fileExists As Boolean
    fileExists = My.Computer.FileSystem.FileExists(IO.Path.Combine(_inProcessDir, _dataFileName))

    Return fileExists

End Function

Private Function IsFileApproved() As Boolean

    Dim fileContents As String
    fileContents = My.Computer.FileSystem.ReadAllText(IO.Path.Combine(_doneDir, _dataFileName))

    If fileContents.Substring(0, 4) = "9999" Then
        Return True
    Else
        Return False
    End If

End Function

Private Function GetFileApprovalStatus() As Boolean

    Dim randNum As New Random
    Dim nextNum = randNum.Next(1, 10)

    '60% of all samples will be approved
    If nextNum > 6 Then
        Return False
    Else
        Return True
    End If

End Function

Public Event StatusChanged(ByVal e As System.EventArgs)

Protected Overridable Sub OnStatusChanged(ByVal e As System.EventArgs) Handles Me.StatusChanged
    _processTimer.Stop()
End Sub

Protected Overrides Sub Finalize()
    MyBase.Finalize()
    _processTimer.Stop()

End Sub

Public Enum Status
    Accepted
    Rejected
    Waiting
End Enum

末级

Module Module1

Private WithEvents detector As NewFileDetector
Private WithEvents newIC As InstrumentConnector
Private ICList As New List(Of InstrumentConnector)
Private fileDirectory As String

Sub Main()

    fileDirectory = "c:\temp\inproc"

    Console.WriteLine("Mock IC program running...")
    Console.WriteLine()
    Console.WriteLine("Press ESC to quit...")

    detector = New NewFileDetector(fileDirectory)


    Dim keyresponse As ConsoleKeyInfo = Nothing

    Do
        keyresponse = Console.ReadKey

    Loop Until keyresponse.Key = ConsoleKey.Escape 'Quit program on ESC

End Sub

Private Sub detector_FilesFound(ByVal e As System.EventArgs) Handles detector.FilesFound

    Console.WriteLine("Files found: {0}", detector.FileList.Count)

    For Each filename In detector.FileList
        newIC = New InstrumentConnector(fileDirectory)
        ICList.Add(newIC)
        newIC.Process(filename)
    Next

End Sub

Private Sub newIC_StatusChanged(ByVal e As System.EventArgs) Handles newIC.StatusChanged
    Console.WriteLine("File: {0} Status: {1}", newIC.DataFileName, newIC.FileStatus.ToString)
    ICList.Remove(newIC)

End Sub

终端模块

Answer 1

在这方面有点晚了，但是：这正是Microsoft的CAB框架解决的问题。 它允许任何事件具有多个订阅者和多个发布者。

有了这个框架提供的一个开放源码的版本在这里 。

Answer 2

事件的存储方式与InstrumentConnectors的存储方式无关。 一个List(Of T)很好。

您可以将侦听器类连接到多个事件源。 这就是.NET中的标准模式具有sender参数的原因。 只需将其投射到InstrumentConnector即可。

也就是说，只要StatusChanged是根据规则设计的。

---

好，拿2。

现在有太多代码。 很难通过。

   Public Event StatusChanged(ByVal e As System.EventArgs)

没有正确定义。 应该是

   Public Event StatusChanged(ByVal sender as Object,  ByVal e As System.EventArgs)

而且，我的VB有点生疏，在“句柄”符号旁边，您应该可以声明（在某处）

 HandlesEvent Me.StatusChangedHandler, someInstrument.Statuschanged  ' very sloppy approx

然后在您选择的课程中（可能是表格）

 Sub StatusChangedHandler(ByVal sender as Object,  ByVal e As System.EventArgs)
    Dim InsConn as InstrumentConnector = sender ' may need a CType() here
    .... 
 End Sub