Question

我已经解决了这个问题，我使用backgroundWorker检查数据库是否 OPEN ，这是我的代码：

Public Class Form1

    Delegate Sub SetLabelText_Delegate(ByVal [Label] As Label, ByVal [text] As String)

    Dim sqlconnection As New SqlConnection("Data Source=" & My.Settings.Server & ";Initial Catalog=" & My.Settings.Database & ";Integrated Security=false;user id=" & My.Settings.Username & ";password=" & My.Settings.Password & ";Connection Timeout=5;")

    Dim connectionStatus As String

    Private Sub SetLabelText_ThreadSafe(ByVal [Label] As Label, ByVal [text] As String)
        If [Label].InvokeRequired Then
            Dim MyDelegate As New SetLabelText_Delegate(AddressOf SetLabelText_ThreadSafe)
            Me.Invoke(MyDelegate, New Object() {[Label], [text]})
        Else
            [Label].Text = [text]
        End If
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'I store my database information to my.settings then display it on textboxes for manipulation
        TextBox1.Text = My.Settings.Server
        TextBox2.Text = My.Settings.Database
        TextBox3.Text = My.Settings.Username
        TextBox4.Text = My.Settings.Password

        'just getting my computer name
        lblCompName.Text = System.Windows.Forms.SystemInformation.ComputerName

        BackgroundWorker1.RunWorkerAsync()
    End Sub

    Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork

        Try

            If sqlconnection.State = ConnectionState.Closed Then
                sqlconnection.Open()
                connectionStatus = "Online"
                'sqlconnection.Open()
                SetLabelText_ThreadSafe(Me.Label1, "Database Status: online")
            End If

        Catch ex As Exception
            connectionStatus = "Offline"
            sqlconnection.Close()
            SetLabelText_ThreadSafe(Me.Label1, "Database Status: offline")
        End Try

    End Sub

    Private Sub BackgroundWorker1_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted

        If e.Error IsNot Nothing Then
            Label1.Text = "Database Status: " & connectionStatus
        Else
            Label1.Text = "Database Status: " & connectionStatus
        End If
        BackgroundWorker1.RunWorkerAsync()
    End Sub
end class

在上面的代码中，它确实有效，它在Visual Studio中重新启动程序时会显示＆＃34; database is online/offline＆＃34; ，但是当我运行该程序时关闭/禁用我的网络连接（我的数据库在其他计算机上）它始终显示 "Database is ONLINE" ，但我很确定我的电脑和数据库之间已经没有连接（因为我PING）因此必须显示为 "Database is oFFLINE" 。

我是否错过了使用 backgroundWOrker 的相关信息？哦顺便说一下，我是 BackgroundWorker 的新手。非常感谢任何帮助或替代解决方案，谢谢！

使用后台工作者检查数据库连接

0 个答案: