.net - VB.NET-在单独的线程中进行工作以防止Form挂起

Question

我有一个非常简单的窗体，带有一个按钮，该按钮会触发我创建的Sub，该Sub从ActiveDirectory收集数据并将其添加到Excel工作表中。

问题是，当我单击此按钮时，整个表单将挂起。因此，我认为收集数据并将其添加到Excel工作表的操作应在其自己的线程中运行，以使表单不会挂起。可能还需要添加进度条。
但是，进度栏位于主用户窗体上，该窗体在项目运行后即会启动。

为了达到我想要的方式，我需要做什么？

编辑:添加了一些我的代码。我有一个MainForm.vb和一个CodeFile.vb。
我想要CodeFile.vb中的大多数代码，因此比较整齐。

MainForm.vb

Imports User_edit.CodeFile
Imports System.ComponentModel

Public Class MainForm
    Private Sub btnImportData_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnImportData.Click
        If MyBackgroundWorker.IsBusy <> True Then
            MyBackgroundWorker.RunWorkerAsync()
        End If
    End Sub

    Private Sub BackgroundWorker_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles MyBackgroundWorker.DoWork
        ExportADUsers()
    End Sub

    Private Sub BackgroundWorker_ProgressChanged(ByVal sender As System.Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles MyBackgroundWorker.ProgressChanged
        statusBarLabel.Text = (e.ProgressPercentage.ToString)
    End Sub

    Private Sub BackgroundWorker_RunWorkerCompleted(ByVal sender As System.Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles MyBackgroundWorker.RunWorkerCompleted
        statusBarLabel.Text = "Finished"
    End Sub
End Class

CodeFile.vb

Imports System.DirectoryServices
Imports System.ComponentModel
Imports System.Threading

Module CodeFile
    Public Sub ExportADUsers()
        MainForm.MyBackgroundWorker.WorkerReportsProgress = True
        MainForm.MyBackgroundWorker.WorkerSupportsCancellation = True

        Dim i As Integer

        Dim objRootDSE, strRoot, strfilter, strAttributes, strScope
            objRootDSE = GetObject("LDAP://RootDSE")
            strRoot = objRootDSE.GET("DefaultNamingContext")
            strfilter = "(&(objectCategory=Person)(objectClass=User))"
            strAttributes = "mail,userPrincipalName,givenName,sn," & _
              "initials,displayName,physicalDeliveryOfficeName," & _
              "telephoneNumber,mail,wWWHomePage,profilePath," & _
              "scriptPath,homeDirectory,homeDrive,title,department," & _
              "company,manager,homePhone,pager,mobile," & _
              "facsimileTelephoneNumber,ipphone,info," & _
              "streetAddress,postOfficeBox,l,st,postalCode,c"
            'Scope of the search.  Change to "onelevel" if you didn't want to search child OU's
            MainForm.statusBarLabel.Text = "Collecting data"
        strScope = "subtree"

            Dim cn, cmd, rs
            cn = CreateObject("ADODB.Connection")
            cmd = CreateObject("ADODB.Command")

            cn.open("Provider=ADsDSOObject;")
            cmd.ActiveConnection = cn
            cmd.commandtext = "<LDAP://" & strRoot & ">;" & strfilter & ";" & _
                                strAttributes & ";" & strScope

            rs = cmd.EXECUTE

            Dim objExcel, objWB, objSheet

            objExcel = CreateObject("Excel.Application")
            objWB = objExcel.Workbooks.Add
        objSheet = objWB.Worksheets(1)

        For i = 0 To rs.Fields.Count - 1
            MainForm.MyBackgroundWorker.ReportProgress(i * 10)
            objSheet.Cells(1, i + 1).Value = rs.Fields(i).Name
            objSheet.Cells(1, i + 1).Font.Bold = True
        Next

            Dim strExportFile
            strExportFile = "C:\users\vsando\desktop\export.xls"

            objSheet.Range("A2").CopyFromRecordset(rs)
            objSheet.SaveAs(strExportFile)

            'Clean up
            rs.Close()
            cn.Close()
            objSheet = Nothing
            objWB = Nothing
            objExcel.Quit()
            objExcel = Nothing

    End Sub

注意我在 ExportFromAD中获得的 CodeFile.vb Sub。这实际上是在做的工作。在For每个将数据添加到Excel的循环中，我都放置了 MainForm.MyBackgroundWorker.ReportProgress(i * 10)。

问题是，它实际上并没有更新表单上的标签。我觉得这很奇怪，因为表格没有真正悬挂或其他任何东西。它是在尝试访问其他线程还是其他东西？意思是，表单是在它自己的线程上运行的，无法从我的第二个线程访问它？

Answer 1

最好的选择是使用 BackgroundWorker ，因为此类是为这种精确的用例而设计的。

这也允许您call back to the form to update the status bar。