当我使用后台工作程序时出现问题 [英] Problem appear when I am using background worker

问题描述

当我使用后台工作程序时，我得到了不清楚的消息'

跨线程操作无效：控制'Panel4'从线程以外的线程访问是创建的。

但是如果按常规到正常按钮它工作正常但我在完成过程后挂起这个过程一切都可以使用。



使用后台工作人员的正确方法是什么？



< b>我尝试了什么：

 私人  Sub  BtnOk_Click（发件人作为 对象，e  As  EventArgs）句柄 BtnOk.Click 
 '  尝试 
 如果 BW.IsBusy =  True  然后 
 如果 MsgBox（ 有一个进程正在运行，你想杀死进程吗？，MsgBoxStyle.YesNo + MsgBoxStyle.Information，< span class =code-string>  Process）= MsgBoxResult.Yes 然后 
 BW.CancelAsync（）
 结束 如果 
  Else  
 BW.RunWorkerAsync（）
 结束 如果 
 
 结束  Sub  

< pre> Private  Sub  BW_DoWork（发送者作为 对象，e  As  System.ComponentModel.DoWorkEventArgs）句柄 BW.DoWork 
 
 如果 不 conn.State = ConnectionState.Open 然后 conn.Open（）
 SaveInto.Connection = conn 
 SaveInto.CommandText =   DELETE FROM TrialBalance 
 SaveInto.ExecuteNonQuery（）
 
 选择 案例 Period_Choice 
 案例   0 '  Uptodate  
 选择 案例 AllBr_Status 
 案例  True  
 选择 < span class =code-keyword>案例 RepType 
 案例  < span class =code-string> 0 
 选择 案例 Level_Choice 
 案例   1 
 ' سلكتللمستوىالاولكاجمالياتبدونتحديدايفرع 
  Dim  Account_Code，Account_Name  As   Stri ng  
  Dim  Selected_row 作为  Boolean  
 PB.Maximum =  Me  .AccountsList.Rows.Count 
 
 PB.Visible =  True  
 
 对于 每个 r1 作为 DataGridViewRow 在 我 .AccountsList.Rows 
 Selected_row = r1.Cells（ 0 ）。值
 Account_Code = Trim（r1.Cells（ 1 ）。值）
 Account_Name =修剪（r1.Cells（ 2 ）。值）
 
 如果 Selected_row =  True  然后 
 SaveInto.CommandText =   INSERT INTO TrialBalance（帐户，名称，OpenBalance）
（SELECT Main_Gr_Code，Main_Gr_Name，Sum（ISNULL（OP_BAL _&修剪（CurYear）&  ，0.00））
 FROM Acc_OBAL 
 GROUP BY Main_Gr_Code，Main_Gr_Name 
拥有Main_Gr_Code ='&修剪（Account_Code）&  '） 
 如果 不 conn.State = ConnectionState.Open 然后 conn.Open（）
 SaveInto.ExecuteNonQuery （）
 SaveInto.CommandText =  更新TrialBalance SET TransactionBalance = 
 ISNULL（（SELECT SUM（ Dr_Acc_Value） -  sum（Cr_Acc_Value）As Tot 
来自JV_QRY 
 Group By Main_Gr_Code，JV_Year 
 HAVING Main_Gr_Code ='& Trim（Account_Code）&  '
并且JV_Year ='& CurYear&  '），0.00）
其中Account ='&修剪（Account_Code）&  ' 
 
 如果 不 conn.State = ConnectionState.Open 然后 conn.Open（）
 SaveInto.ExecuteNonQuery（）
 结束 如果 
 PB.Value + =  1  
 下一步 
 PB.Visible = 错误 
 PB.Value =  0  

解决方案

< blockquote>您只能从创建它们的线程访问UI控件 - U.我线程。如果你试图在后台工作者中做任何事情 - 这是一个不同的线程 - 你将得到一个交叉线程例外。



而是使用< a href =https://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.reportprogress%28v=vs.110%29.aspx?f=255&MSPPError=-2147217396> BackgroundWorker。 ReportProgress方法 [ ^ ]将信息传递给UI线程并让它处理UI更新。

似乎你的问题被定义为：如何使用多线程？



检查：

如何：对Windows窗体控件进行线程安全调用 [ ^ ]

如何：使用后台线程搜索文件 [ ^ ]



这也很有用：

c＃ - 跨线程操作无效：从其创建的线程以外的线程访问控件 - Stack Overflow [ ^ ]

Hi,
When i am using background worker i got unclear message '

Cross-thread operation not valid: Control 'Panel4' accessed from a thread other than the thread it was created on.

but if take the routine to the normal button it is working perfectly but i got hang while the process then after finishing the process everything can be usable.

what is the correct way to use Background worker?

What I have tried:

Private Sub BtnOk_Click(sender As Object, e As EventArgs) Handles BtnOk.Click
        'Try
        If BW.IsBusy = True Then
            If MsgBox("There is a process is running, Do you like to kill the process?", MsgBoxStyle.YesNo + MsgBoxStyle.Information, "Process") = MsgBoxResult.Yes Then
                BW.CancelAsync()
            End If
        Else
            BW.RunWorkerAsync()
        End If

    End Sub

<pre>Private Sub BW_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BW.DoWork

        If Not conn.State = ConnectionState.Open Then conn.Open()
        SaveInto.Connection = conn
        SaveInto.CommandText = "DELETE FROM TrialBalance"
        SaveInto.ExecuteNonQuery()

        Select Case Period_Choice
            Case "0" 'Uptodate
                Select Case AllBr_Status
                    Case True
                        Select Case RepType
                            Case "0"
                                Select Case Level_Choice
                                    Case "1"
                                        'سلكت للمستوى الاول كاجماليات بدون تحديد اي فرع
                                        Dim Account_Code, Account_Name As String
                                        Dim Selected_row As Boolean
                                        PB.Maximum = Me.AccountsList.Rows.Count

                                        PB.Visible = True

                                        For Each r1 As DataGridViewRow In Me.AccountsList.Rows
                                            Selected_row = r1.Cells(0).Value
                                            Account_Code = Trim(r1.Cells(1).Value)
                                            Account_Name = Trim(r1.Cells(2).Value)

                                            If Selected_row = True Then
                                                SaveInto.CommandText = "INSERT INTO TrialBalance(Account,Name,OpenBalance) 
                                                            (SELECT Main_Gr_Code,Main_Gr_Name,Sum(ISNULL(OP_BAL_" & Trim(CurYear) & ",0.00))
                                                            FROM Acc_OBAL 
                                                            GROUP BY Main_Gr_Code,Main_Gr_Name
                                                           HAVING Main_Gr_Code = '" & Trim(Account_Code) & "')"
                                                If Not conn.State = ConnectionState.Open Then conn.Open()
                                                SaveInto.ExecuteNonQuery()
                                                SaveInto.CommandText = "Update TrialBalance SET TransactionBalance = 
                                                ISNULL((SELECT SUM(Dr_Acc_Value) - sum(Cr_Acc_Value) As Tot
                                                From JV_QRY
                                                Group By Main_Gr_Code, JV_Year
                                                HAVING Main_Gr_Code = '" & Trim(Account_Code) & "'
                                                And JV_Year = '" & CurYear & "'),0.00)
                                                where Account = '" & Trim(Account_Code) & "'"

                                                If Not conn.State = ConnectionState.Open Then conn.Open()
                                                SaveInto.ExecuteNonQuery()
                                            End If
                                            PB.Value += 1
                                        Next
                                        PB.Visible = False
                                        PB.Value = 0

解决方案

You can only access UI controls from the thread on which they were created - the UI thread. If you try to do anything at all with them from within a background worker - which is a different thread - you will get a cross threading exception.

Instead use the BackgroundWorker.ReportProgress method[^] to pass the information to the UI thread and let it deal with UI updates.

Seems your problem is defined as: How to use multithreading?

Check this:
How to: Make Thread-Safe Calls to Windows Forms Controls[^]
How to: Use a Background Thread to Search for Files[^]

This can be useful too:
c# - Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on - Stack Overflow[^]

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