带有进程的进度条

Question

当我单击命令按钮时，需要几秒钟才能完成可能使最终用户认为程序滞后的过程，然后我想到了进度条。那么如何在进程运行时使进度条工作，以便用户不会认为程序滞后，我是 vb.net 的新手，我现在研究了一段时间，但仍然无法了解它是如何工作的也不知道如何开始。

提前感谢您的帮助

这是我的命令按钮进程。

        Private Sub LoginBTN_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LoginBTN.Click
    Using ClientDashboardx As New ClientDashboard
        Try

            cn = New ADODB.Connection
            conDB()
            cn.Open()

            rs = New ADODB.Recordset
            rs.Open("SELECT * FROM tb_registration", cn, 0, 3)

            If txtuserid.Text = "" Or txtuserpass.Text = "" Then
                MsgBox("Value Null")
                Exit Sub
            Else
                Do While Not rs.EOF
                    Dim strLogin = txtin.Text
                    Dim strLogout = txtout.Text
                    If rs("st_acc_number").Value = txtuserid.Text And rs("st_password").Value = txtuserpass.Text And rs("st_log").Value = strLogin Then
                        MsgBox("Account in use")
                        Exit Sub
                    ElseIf rs("st_acc_number").Value = txtuserid.Text And rs("st_password").Value = txtuserpass.Text And rs("st_log").Value = strLogout Then
                        Dim strID = rs("st_acc_number").Value
                        Dim strUserName = rs("st_fname").Value & " " & rs("st_lname").Value
                        Dim strTotalTime = rs("st_totaltimeleft").Value
                        rs.Close()
                        SaveAccNumber.Text = strID
                        SaveUserName.Text = strUserName
                        SaveTotalTime.Text = strTotalTime

                        cn.BeginTrans()
                        cn.Execute("UPDATE tb_registration SET st_log='in' where st_acc_number='" & SaveAccNumber.Text & "'")
                        cn.CommitTrans()
                        cn.Close()

                        ClientDashboardx.id_lbl.Text = SaveAccNumber.Text
                        ClientDashboardx.iduser_lbl.Text = SaveUserName.Text
                        ClientDashboardx.UserTotalTime.Text = SaveTotalTime.Text
                        ClientDashboardx.AutoUpdate_Button.Enabled = True
                        Me.Hide()
                        ClientDashboardx.ShowDialog()
                        Me.Show()
                        Exit Sub
                    Else
                        rs.MoveNext()
                    End If
                Loop
                MsgBox("User/Pass Mismatch")
                Exit Sub
            End If
        Catch ex As Exception
            MsgBox("Server Offline", MsgBoxStyle.Critical, "")
        End Try
    End Using
End Sub

Answer 1

您应该在单独的线程或background worker 中执行长时间运行的进程。

这里是如何使用后台工作者：

将 BackgroundWorker 和 ProgressBar 添加到您的表单

添加一个私有变量来保存你的结果

Private _success As Boolean

添加代码以显示 ProgressBar 并在 Form_Load 中启动工作器

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    _success = False
    ProgressBar1.Style = ProgressBarStyle.Marquee
    ProgressBar1.Visible = True
    BackgroundWorker1.RunWorkerAsync()
End Sub

在此处执行您的长期操作

Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
    'perform your db access here and set the result in _success
End Sub

当工人完成隐藏进度条并根据结果执行一些操作

Private Sub BackgroundWorker1_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
    ProgressBar1.Visible = False
    If _success Then
        Me.Hide()
        ClientDashboardx.ShowDialog()
        Me.Show()
    Else
        MsgBox("User/Pass Mismatch")
    End If
End Sub