跨线程操作无效;从控制比我在进度条

Question

我收到此错误使用线程的线程上“ListView1的” acccessed ..

我试图做的进度条，处理数据库插入方法有超过1000条记录。我需要进度条加载完全相同的线程处理..

我得到了错误;跨线程操作无效;控制'listview1'从一个线程访问，而不是它创建的线程。

Imports System.IO 
Public Class Form1 
    Private WithEvents DT As New DataTable 
    Private Delegate Sub AsyncDelegate(ByVal value As Integer) 
    Private ProgressUpdater As New AsyncDelegate(AddressOf UpdateProgress) 
    Private DataLoader As AsyncDelegate 
    Private DataLoaderIAsync As IAsyncResult 
    Private UpdateIncrement As Integer 

    Private Sub LoadListAttendance() 
     Dim txtLine As String = "" 
     ListView1.Items.Clear() 
     If File.Exists(strFileNameAndPath) = True Then 
      Dim objReader As New StreamReader(strFileNameAndPath) 

      Do While objReader.Peek() <> -1 
       Dim strLine As String = objReader.ReadLine() 
       If Split(strLine, " ")(0) = "" Then MessageBox.Show("Invalid file.", SysMsg, MessageBoxButtons.OK) : Exit Sub 
       ListView1.Items.Add(Split(strLine, " ")(0)) 
       ListView1.Items(ListView1.Items.Count - 1).SubItems.Add(Mid(Split(strLine, " ")(1), 1, 8)) 
       ListView1.Items(ListView1.Items.Count - 1).SubItems.Add(Mid(Split(strLine, " ")(1), 9, 4)) 
       ListView1.Items(ListView1.Items.Count - 1).SubItems.Add(Mid(Split(strLine, " ")(1), 13, 2)) 
      Loop 
     End If 
    End Sub 


    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click 
     'Initialize the progress bar. 

     'Run a scalar command to select the row count and set the progress maximum 

     'Calculate a percentage for the Row Changed event. 
     ' ie if total recs is 1,000,000 set the progress amount to 10% of that. 
     ' *See DT_RowChanged 

     UpdateIncrement = 100000 

     'DeEnable any controls you may not want the user to touch until the 
     'load is complete. 

     'Load the data Ascync 
     DataLoader = New AsyncDelegate(AddressOf LoadData) 
     DataLoaderIAsync = DataLoader.BeginInvoke(0, New AsyncCallback(AddressOf LoadData_Completed), Nothing) 


    End Sub 





    Private Sub LoadData() 

     'Your Load data code. 
     'This sample code loads 1,000,000 recs 

     'Do not access any controls in the procedure 
     If Not checkServer() = True Then frmServerSet.ShowDialog() 
     For x As Integer = 0 To ListView1.Items.Count - 1 
      'If RecExist_2("tbltxt", "date", ListView1.Items(x).SubItems(1).Text, "id", ListView1.Items(x).Text, False) = False Then 
      sqlSTR = "insert into tbltxt (id,date,time,code) values" 
      sqlSTR = sqlSTR & " ('" & ListView1.Items(x).Text & "','" & ListView1.Items(x).SubItems(1).Text & "','" & ListView1.Items(x).SubItems(2).Text & "', '" & ListView1.Items(x).SubItems(3).Text & "')" ','" & t1 & "')" 

      ExecuteSQLQuery(sqlSTR) 

      'End If 
     Next 
     MsgBox("ok") 
    End Sub 

    Private Sub LoadData_Completed() 

     'Async op has completed. 
     'Call the endinvoke to the delegate and unlock the UI 

     'Do not access any controls in this procedure 

     DataLoader.EndInvoke(DataLoaderIAsync) 

     Me.Invoke(New AsyncDelegate(AddressOf UnlockUI), New Object() {Nothing}) 

    End Sub 

    Private Sub UnlockUI() 
     'Do what you want to the UI Here. 
     ProgressBar1.Visible = False 

    End Sub 

    Private Sub UpdateProgress(ByVal value As Integer) 
     'Updates the progress bar from the thread it was 
     'created on. 
     If ProgressBar1.InvokeRequired Then 
      ProgressBar1.Invoke(ProgressUpdater, New Object() {value}) 
     Else 
      If value > ProgressBar1.Maximum Then value = ProgressBar1.Maximum 
      ProgressBar1.Value = value 
     End If 

    End Sub 

    Private Sub DT_RowChanged(ByVal sender As Object, ByVal e As System.Data.DataRowChangeEventArgs) Handles DT.RowChanged 
     'Handle a row change 
     'Do not access any controls from this procedure 

     Static counter As Integer = 1 

     'first make sure the row is being added 
     If e.Action = DataRowAction.Add Then 
      'next check for an increment. In this case I have a hard coded 
      '100,000 Which is 10% of the million records that I know I have. 

      'Do not update the progress bar on every record 

      If counter Mod UpdateIncrement = 0 Then 
       UpdateProgress(counter) 
      End If 
      counter += 1 
     End If 

    End Sub 
End Class 

Answer 1

LoadData在后台线程上运行;你不能谈话从这个线程的列表视图（甚至读取值）。更常见。你将在UI线程上从UI构建一些模型（我将有一个自定义类的列表将每个值表示为属性），然后使该模型对工作线程可用。然后在后台线程中，您只能访问与您的模型无关的UI。

另请参见：不要连接值以生成SQL。这是自杀 - 这是一个明显的SQL注入风险。相反，请使用无参数查询，或者为您处理参数化的工具。