VB.Net 线程和 Addhandler 问题
VB.Net Threading and Addhandler Troubles
Whosebug 社区大家好！
我正在研究 class "SendLogfileClass"。在此 class 中，我通过电子邮件将日志文件发送到所述电子邮件帐户。该部分按预期工作。我遇到的问题是尝试处理异步完成事件。在上述事件中，Addhandler 触发并在主窗体上设置 StatusBar.StatusLabel。
以下是一些相关的代码块：
#Region "Imports"
Imports System
Imports System.Net
Imports System.Net.Mail
Imports System.Net.Mime
Imports System.Threading
Imports System.ComponentModel
Imports System.IO
#End Region
Public Class Form1
#Region "Public"
Private SendmailThread As Thread
Private MailBody As String = Nothing
#End Region
#Region "Private"
Private mailSent As Boolean = False
#End Region
Public Function GetTimestamp() As String
Dim t As Date = Date.Now
Dim timestamp As String = Nothing
Try
timestamp = t.ToLongTimeString & " " & t.ToLongDateString
Catch ex As Exception
Return 1
End Try
Return timestamp
End Function
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Try
If LoggerClock.Enabled = True Then
OutputConsole.Text = "logger Started: " & GetTimestamp() & vbNewLine
OutputConsole.AppendText("Logfile Opened: " & GetTimestamp() & vbNewLine)
StatusLabel.Text = "Logger Status: Active"
StatusBar.Refresh()
Else
OutputConsole.Text = "logger Started: " & GetTimestamp() & vbNewLine
StatusLabel.Text = "Logger Status: Inactive"
StatusBar.Refresh()
End If
SendlogClock.Enabled = True
ToggleViewForm(1)
Catch ex As Exception
Exit Sub
End Try
End Sub
Public Function SetStatus(ByVal [status] As String) As Integer
Try
Thread.Sleep(1000)
StatusLabel.Text = [status]
StatusBar.Refresh()
Catch ex As Exception
Return 1
End Try
Return 0
End Function
Private Sub SendlogThreadTask()
Try
SendLogfile("user@gmail.com", "Logger Logfile", MailBody).ToString()
Catch ex As Exception
Exit Sub
End Try
End Sub
Private Sub SendlogClock_Tick(sender As Object, e As EventArgs) Handles SendlogClock.Tick
Try
OutputConsole.AppendText("Logfile Closed: " & GetTimestamp() & vbNewLine)
SendmailThread = New Thread(AddressOf SendlogThreadTask)
SendmailThread.IsBackground = True
SendmailThread.Start()
OutputConsole.ResetText()
OutputConsole.Text = "Logfile Opened: " & GetTimestamp() & vbNewLine
Catch ex As Exception
Exit Sub
End Try
End Sub
Public Sub SendCompletedCallback(ByVal sender As Object, ByVal e As AsyncCompletedEventArgs)
Try
' Get the unique identifier for this asynchronous operation.
Dim token As String = CStr(e.UserState)
If e.Cancelled Then
StatusLabel.Text = "Send Canceled... " & token
StatusBar.Refresh()
End If
If e.Error IsNot Nothing Then
StatusLabel.Text = "Error: " & token & " " & e.Error.ToString() & " "
StatusBar.Refresh()
Else
StatusLabel.Text = "Message Sent... "
StatusBar.Refresh()
End If
mailSent = True
Catch ex As Exception
Exit Sub
End Try
End Sub
Public Function SendLogfile(ByVal mailTo As String, ByVal mailSubject As String, ByVal mailBody As String, Optional ByVal doAttach As Boolean = False, Optional ByVal messageAttach As String = Nothing) As Integer
Try
' SMTP Server
Dim SmtpServer As String = "mail.domain.com"
' Command line argument must the the SMTP host.
Dim Cli As New SmtpClient(SmtpServer)
' Specify the e-mail sender.
' Create a mailing address that includes a UTF8 character
' in the display name.
Dim [from] As New MailAddress("logger@domain.com", "logger " & ChrW(&HD8) & " logs", System.Text.Encoding.UTF8)
' Set destinations for the e-mail message.
Dim [to] As New MailAddress(mailTo)
' Specify the message content.
Dim message As New MailMessage([from], [to])
message.Body = mailBody
' Include some non-ASCII characters in body and subject.
Dim someArrows As New String(New Char() {ChrW(&H2190), ChrW(&H2191), ChrW(&H2192), ChrW(&H2193)})
message.Body += Environment.NewLine & someArrows
message.BodyEncoding = System.Text.Encoding.UTF8
message.Subject = mailSubject & someArrows
message.SubjectEncoding = System.Text.Encoding.UTF8
' Put the mail attachment in a list of items
'Dim attachment As New Attachment(messageAttach)
' Attach file.
'If doAttach = True Then
'If File.Exists(messageAttach) Then
'message.Attachments.Add(attachment)
'End If
'End If
' Set the method that is called back when the send operation ends.
AddHandler Cli.SendCompleted, AddressOf SendCompletedCallback
' The userState can be any object that allows your callback
' method to identify this send operation.
' For this example, the userToken is a string constant.
Dim userState As String = "OK"
Cli.SendAsync(message, userState)
'MsgBox("Sending message... press c to cancel mail. Press any other key to exit.")
Dim answer As String = "OK" ' or CANCEL
' If the user canceled the send, and mail hasn't been sent yet,
' then cancel the pending operation.
If answer.StartsWith("C") AndAlso mailSent = False Then
Cli.SendAsyncCancel()
End If
' Clean up.
message.Dispose()
Catch ex As Exception
MsgBox("Encountered Error: " & vbNewLine & vbNewLine & ex.ToString())
Return 1
End Try
Return 0
End Function
End Class
您的事件处理程序在辅助线程上执行，并且在该事件处理程序中您指的是 MainForm 的默认实例。默认实例是特定于线程的，因此它是一个与您在屏幕上看到的不同的表单对象。
您通常可以使用 SynchronizationContext class 来启用对 UI 线程的方法调用编组，但在您的情况下这是不可能的，因为您实际上是在创建对象辅助线程也是。在这种情况下，您必须将对现有 MainForm 对象的引用传递给该邮件发件人，并使用它来编组对 UI 线程的方法调用，使用其 InvokeRequired 和 Invoke/BeginInvoke 位成员。
Whosebug 社区大家好！
我正在研究 class "SendLogfileClass"。在此 class 中，我通过电子邮件将日志文件发送到所述电子邮件帐户。该部分按预期工作。我遇到的问题是尝试处理异步完成事件。在上述事件中，Addhandler 触发并在主窗体上设置 StatusBar.StatusLabel。
以下是一些相关的代码块：
#Region "Imports"
Imports System
Imports System.Net
Imports System.Net.Mail
Imports System.Net.Mime
Imports System.Threading
Imports System.ComponentModel
Imports System.IO
#End Region
Public Class Form1
#Region "Public"
Private SendmailThread As Thread
Private MailBody As String = Nothing
#End Region
#Region "Private"
Private mailSent As Boolean = False
#End Region
Public Function GetTimestamp() As String
Dim t As Date = Date.Now
Dim timestamp As String = Nothing
Try
timestamp = t.ToLongTimeString & " " & t.ToLongDateString
Catch ex As Exception
Return 1
End Try
Return timestamp
End Function
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Try
If LoggerClock.Enabled = True Then
OutputConsole.Text = "logger Started: " & GetTimestamp() & vbNewLine
OutputConsole.AppendText("Logfile Opened: " & GetTimestamp() & vbNewLine)
StatusLabel.Text = "Logger Status: Active"
StatusBar.Refresh()
Else
OutputConsole.Text = "logger Started: " & GetTimestamp() & vbNewLine
StatusLabel.Text = "Logger Status: Inactive"
StatusBar.Refresh()
End If
SendlogClock.Enabled = True
ToggleViewForm(1)
Catch ex As Exception
Exit Sub
End Try
End Sub
Public Function SetStatus(ByVal [status] As String) As Integer
Try
Thread.Sleep(1000)
StatusLabel.Text = [status]
StatusBar.Refresh()
Catch ex As Exception
Return 1
End Try
Return 0
End Function
Private Sub SendlogThreadTask()
Try
SendLogfile("user@gmail.com", "Logger Logfile", MailBody).ToString()
Catch ex As Exception
Exit Sub
End Try
End Sub
Private Sub SendlogClock_Tick(sender As Object, e As EventArgs) Handles SendlogClock.Tick
Try
OutputConsole.AppendText("Logfile Closed: " & GetTimestamp() & vbNewLine)
SendmailThread = New Thread(AddressOf SendlogThreadTask)
SendmailThread.IsBackground = True
SendmailThread.Start()
OutputConsole.ResetText()
OutputConsole.Text = "Logfile Opened: " & GetTimestamp() & vbNewLine
Catch ex As Exception
Exit Sub
End Try
End Sub
Public Sub SendCompletedCallback(ByVal sender As Object, ByVal e As AsyncCompletedEventArgs)
Try
' Get the unique identifier for this asynchronous operation.
Dim token As String = CStr(e.UserState)
If e.Cancelled Then
StatusLabel.Text = "Send Canceled... " & token
StatusBar.Refresh()
End If
If e.Error IsNot Nothing Then
StatusLabel.Text = "Error: " & token & " " & e.Error.ToString() & " "
StatusBar.Refresh()
Else
StatusLabel.Text = "Message Sent... "
StatusBar.Refresh()
End If
mailSent = True
Catch ex As Exception
Exit Sub
End Try
End Sub
Public Function SendLogfile(ByVal mailTo As String, ByVal mailSubject As String, ByVal mailBody As String, Optional ByVal doAttach As Boolean = False, Optional ByVal messageAttach As String = Nothing) As Integer
Try
' SMTP Server
Dim SmtpServer As String = "mail.domain.com"
' Command line argument must the the SMTP host.
Dim Cli As New SmtpClient(SmtpServer)
' Specify the e-mail sender.
' Create a mailing address that includes a UTF8 character
' in the display name.
Dim [from] As New MailAddress("logger@domain.com", "logger " & ChrW(&HD8) & " logs", System.Text.Encoding.UTF8)
' Set destinations for the e-mail message.
Dim [to] As New MailAddress(mailTo)
' Specify the message content.
Dim message As New MailMessage([from], [to])
message.Body = mailBody
' Include some non-ASCII characters in body and subject.
Dim someArrows As New String(New Char() {ChrW(&H2190), ChrW(&H2191), ChrW(&H2192), ChrW(&H2193)})
message.Body += Environment.NewLine & someArrows
message.BodyEncoding = System.Text.Encoding.UTF8
message.Subject = mailSubject & someArrows
message.SubjectEncoding = System.Text.Encoding.UTF8
' Put the mail attachment in a list of items
'Dim attachment As New Attachment(messageAttach)
' Attach file.
'If doAttach = True Then
'If File.Exists(messageAttach) Then
'message.Attachments.Add(attachment)
'End If
'End If
' Set the method that is called back when the send operation ends.
AddHandler Cli.SendCompleted, AddressOf SendCompletedCallback
' The userState can be any object that allows your callback
' method to identify this send operation.
' For this example, the userToken is a string constant.
Dim userState As String = "OK"
Cli.SendAsync(message, userState)
'MsgBox("Sending message... press c to cancel mail. Press any other key to exit.")
Dim answer As String = "OK" ' or CANCEL
' If the user canceled the send, and mail hasn't been sent yet,
' then cancel the pending operation.
If answer.StartsWith("C") AndAlso mailSent = False Then
Cli.SendAsyncCancel()
End If
' Clean up.
message.Dispose()
Catch ex As Exception
MsgBox("Encountered Error: " & vbNewLine & vbNewLine & ex.ToString())
Return 1
End Try
Return 0
End Function
End Class
您的事件处理程序在辅助线程上执行，并且在该事件处理程序中您指的是 MainForm 的默认实例。默认实例是特定于线程的，因此它是一个与您在屏幕上看到的不同的表单对象。
您通常可以使用 SynchronizationContext class 来启用对 UI 线程的方法调用编组，但在您的情况下这是不可能的，因为您实际上是在创建对象辅助线程也是。在这种情况下，您必须将对现有 MainForm 对象的引用传递给该邮件发件人，并使用它来编组对 UI 线程的方法调用，使用其 InvokeRequired 和 Invoke/BeginInvoke 位成员。