Question

我正在使用Windows窗体应用程序：在我的形式我在某个时间间隔填充我的数据网格视图。所以有一段时间我的应用程序卡住..所以我用了地面工人和计时器
在后台工作人员我调用我的函数来填充我的数据网格视图。我将Timer Interval设置为10000 。在后台工作者我给这样的代码：

Private Sub BackgroundWorker1_DoWork
Call Fetch_Info()
End Sub

在计时器点击事件中我给出了像这样的代码：

 If Not BackgroundWorker1.IsBusy Then
            BackgroundWorker1.RunWorkerAsync()
        End If

我的Fetch_Info（）函数如下：

 Dim cnt As Integer
            Dim tbarcodedgv As String
            Dim totaltbarcode As String
            cnt = DGVall.RowCount
 Dim tbar As String
            Dim locTable As New DataTable
            locTable.Columns.Add("carid", GetType(String))
            If cnt > 0 Then
                For i = 0 To cnt - 2
                  tbarcodedgv = DGVall.Rows(i).Cells(0).Value
 locTable.Rows.Add(tbarcodedgv)
                Next
            End If
Dim flag As Boolean = False
            Dim dcnt As Integer = DGVall.RowCount
            Dim trid As Integer
            Dim tbarcode As String
            Dim keyloc As String
            Dim cmd23 As New SqlCommand("IBS_fetchrequested", con.connect)
            cmd23.CommandType = CommandType.StoredProcedure
            cmd23.Parameters.Add("@tid", SqlDbType.Int).Value = tid
            If cnt > 1 Then
                Dim tvp1 As SqlParameter = cmd23.Parameters.AddWithValue("@Tbaroced", locTable)
                tvp1.SqlDbType = SqlDbType.Structured
                tvp1.TypeName = "dbo.TBarcode"
            End If


            dr = cmd23.ExecuteReader
            While dr.Read
                flag = False
                tbarcode = dr("TBarcode")
If flag = False Then
                    If dr("keyloc") Is DBNull.Value Then
                        keyloc = ""
                    Else
                        keyloc = dr("keyloc")
                    End If

                    Dim row0 As String() = {tbarcode, keyloc, "", "Release"}
                    DGVall.Rows.Add(row0)
                    AxWindowsMediaPlayer1.URL = "C:\Beep.mp3"
                End If
            End While
            dr.Close()
            con.disconnect()

Answer 1

当你的后台工作程序运行在除GUI之外的另一个线程中时，你正在操纵在GUI的线程中运行的Datagridview。这应该通常根本不起作用，但这可能是为什么你的GUI在BGW运行时挂起的原因。

尝试拆分工作：从Backgroundworker的DoWork事件处理程序中执行从数据库中获取数据的耗时，并将结果设置为EventArgs变量的e.Result值。 DoWork功能。

然后，您处理了Backgroundworker的RunWorkerCompleted事件，并在那里使用您在DoWork方法中设置的结果快速更新datagridview。这样，您的GUI与实际耗时的任务无关，只会受到数据网格视图快速更新的影响。

这个代码示例是：

Public Class Form1
Private WithEvents LazyBGW As New System.ComponentModel.BackgroundWorker

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    'This code runs in the UI-Thread
    LazyBGW.RunWorkerAsync()
End Sub

Private Sub LazyBGW_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles LazyBGW.DoWork
    'This code runs in the BGW-Thread
    Dim a As Integer = 0
    For i = 1 To 5
        a += 1
        'I'm a lazy worker, so after this hard work I need to...
        Threading.Thread.Sleep(1000) 'This locks up the BGW-Thread, not the UI-thread
    Next
    'Work is done, put results in the eventargs-variable for further processing
    e.Result = a
End Sub

Private Sub LazyBGW_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles LazyBGW.RunWorkerCompleted
    'This code runs in the UI-Thread
    Dim results As Integer = CInt(e.Result) 'e.Result contains whatever you put into it in the DoWork() method
    MessageBox.Show("Finally the worker is done and our result is: " & results.ToString)
End Sub
End Class

使用后台工作者后，我的应用程序卡住了，我怎么解决

1 个答案: