关闭VB.NET后，Excel仍在任务管理器中打开

Question

我创建了一个在VB.NET中创建几个Excel电子表格的应用程序

我遇到的问题是我无法让Excel完全退出。

我在隐藏了Excel的VB.NET中创建并填充工作簿，该过程（Microsoft Excel）在任务管理器的后台进程中显示

完成后，我将Excel显示为可见，并且该过程将移至应用程序。

然后当我关闭Excel时，该过程又回到后台进程。

知道我做错了吗？

代码：

    Dim oExcel As Excel.Application = Nothing
    Dim oWorkbook As Excel.Workbook = Nothing
    Dim oWorksheet As Excel.Worksheet = Nothing
    Dim oRange As Excel.Range = Nothing

    oExcel = CreateObject("Excel.Application")
    oExcel.DisplayAlerts = False
    oExcel.Visible = False

    oWorkbook = oExcel.Workbooks.Add
    oWorksheet = oWorkbook.ActiveSheet
    'Populate, format, etc.
    oWorkbook.SaveAs(Me.txtExportLocation.Text & "\sales.xlsx")

    oExcel.Visible = True

    oRange = Nothing
    oWorksheet = Nothing
    oWorkbook = Nothing

    ReleaseObject(oExcel)

    Public Sub ReleaseObject(ByVal obj As Object)

         Dim iValue As Integer = 0

         Try
             Do
                 iValue = System.Runtime.InteropServices.Marshal.ReleaseComObject(obj)
             Loop While iValue > 0
         Catch ex As Exception
             RaiseError("", "modGeneral." & "." & System.Reflection.MethodBase.GetCurrentMethod().Name, Err.Number, Err.Description)
             obj = Nothing
         Finally
             GC.Collect()
         End Try

     End Sub

更新2016年10月31日：

好的，现在我真的很困惑。

使用此代码获取以下建议，我可以通过一个警告让Excel完全退出：

        GC.Collect()
        GC.WaitForPendingFinalizers()
        System.Runtime.InteropServices.Marshal.ReleaseComObject(oWorksheet) : oWorksheet = Nothing
        System.Runtime.InteropServices.Marshal.ReleaseComObject(oWorkbook) : oWorkbook = Nothing
        System.Runtime.InteropServices.Marshal.ReleaseComObject(oExcel) : oExcel = Nothing

但是，我的代码正在创建两个工作簿。除SQL之外，创建每个工作簿的代码是相同的。如果用户勾选chkA，则清理代码不起作用。如果他们检查chkB它确实有效。如果他们同时检查两者，它就不起作用。我在下面列出了完整的代码：

    Private Sub btnExport_Click(sender As Object, e As EventArgs) Handles btnExport.Click

    Dim oExcel As Excel.Application = Nothing
    Dim oWorkbook As Excel.Workbook = Nothing
    Dim oWorksheet As Excel.Worksheet = Nothing
    Dim drSystem As SqlClient.SqlDataReader = Nothing
    Dim sSQL As String = ""
    Dim iRowCount As Integer = 2

    Try
        If Not Me.chkA.Checked And Not Me.chkB.Checked Then
            MsgBox("Select A, B or both before continuing.", vbInformation)
            Exit Try
        End If

        Me.Cursor = Cursors.WaitCursor
        Me.lblStatus.Text = "Exporting sales..."

        oExcel = CreateObject("Excel.Application")
        oExcel.DisplayAlerts = False
        oExcel.Visible = False

        If Me.chkA.Checked Then
            oWorkbook = oExcel.Workbooks.Add
            oWorksheet = oWorkbook.ActiveSheet
            oWorksheet.Cells(1, 1).Value = "Ship date"
            oWorksheet.Cells(1, 2).Value = "Customer"
            oWorksheet.Cells(1, 3).Value = "Invoice"
            oWorksheet.Cells(1, 4).Value = "Purchase order"
            oWorksheet.Cells(1, 5).Value = "Railcar"
            oWorksheet.Cells(1, 6).Value = "Weight"
            oWorksheet.Cells(1, 7).Value = "Total"
            oWorksheet.Cells(1, 8).Value = "Member purchase order"

            sSQL = "SELECT FORMAT(i.ship_date, N'MM/dd/yyyy') AS ship_date, "
            sSQL += "i.customer_no, "
            sSQL += "i.invoice_number, "
            sSQL += "i.customer_purchase_order_no, "
            sSQL += "r.railcar_number, "
            sSQL += "r.weight, "
            sSQL += "r.total, "
            sSQL += "i.member + N'-' + i.member_purchase_order_no AS member_purchase_order_no "
            sSQL += "FROM Invoices i "
            sSQL += "JOIN Railcars r "
            sSQL += "ON i.invoice_number = r.invoice_number "
            sSQL += "WHERE i.ship_date BETWEEN N'" & Format(Me.dtpStartDate.Value, "MM/dd/yyyy") & "' AND N'" & Format(Me.dtpEndDate.Value, "MM/dd/yyyy") & "' AND "
            sSQL += "invoice_type = N'A' "
            sSQL += "ORDER BY i.customer_no, "
            sSQL += "i.ship_date, "
            sSQL += "r.railcar_number"
            drSystem = modGeneral.drRunSQL(sSQL, CommandType.Text)
            Do While drSystem.Read
                oWorksheet.Cells(iRowCount, 1).Value = drSystem("ship_date")
                oWorksheet.Cells(iRowCount, 2).Value = drSystem("customer_no")
                oWorksheet.Cells(iRowCount, 3).Value = drSystem("invoice_number")
                oWorksheet.Cells(iRowCount, 4).Value = drSystem("customer_purchase_order_no")
                oWorksheet.Cells(iRowCount, 5).Value = drSystem("railcar_number")
                oWorksheet.Cells(iRowCount, 6).Value = drSystem("weight")
                oWorksheet.Cells(iRowCount, 7).Value = drSystem("total")
                oWorksheet.Cells(iRowCount, 8).Value = drSystem("member_purchase_order_no")
                iRowCount += 1
            Loop
            drSystem.Close()
            With oWorksheet.Range("A1", "J1")
                .Font.Bold = True
                .EntireColumn.AutoFit()
            End With
            oWorksheet.Range("D1").EntireColumn.HorizontalAlignment = Excel.Constants.xlLeft
            With oWorksheet.Range("F1")
                .EntireColumn.HorizontalAlignment = Excel.Constants.xlRight
                .EntireColumn.NumberFormat = "#,##0.00_);(#,##0.00)"
            End With
            With oWorksheet.Range("G1")
                .EntireColumn.HorizontalAlignment = Excel.Constants.xlRight
                .EntireColumn.NumberFormat = "#,##0.00_);(#,##0.00)"
            End With
            oWorkbook.SaveAs(Me.txtExportLocation.Text & "\sales-a.xlsx")
        End If
        If Me.chkB.Checked Then
            iRowCount = 2
            oWorkbook = oExcel.Workbooks.Add
            oWorksheet = oWorkbook.ActiveSheet
            oWorksheet.Cells(1, 1).Value = "Ship date"
            oWorksheet.Cells(1, 2).Value = "Customer"
            oWorksheet.Cells(1, 3).Value = "Invoice"
            oWorksheet.Cells(1, 4).Value = "Purchase order"
            oWorksheet.Cells(1, 5).Value = "Railcar"
            oWorksheet.Cells(1, 6).Value = "Weight"
            oWorksheet.Cells(1, 7).Value = "Total"
            oWorksheet.Cells(1, 8).Value = "Member purchase order"

            sSQL = "SELECT FORMAT(i.ship_date, N'MM/dd/yyyy') AS ship_date, "
            sSQL += "i.customer_no, "
            sSQL += "i.invoice_number, "
            sSQL += "i.customer_purchase_order_no, "
            sSQL += "r.railcar_number, "
            sSQL += "r.weight, "
            sSQL += "r.total, "
            sSQL += "i.member + N'-' + i.member_purchase_order_no AS member_purchase_order_no "
            sSQL += "FROM mxInvoices i "
            sSQL += "JOIN mxRailcars r "
            sSQL += "ON i.invoice_number = r.invoice_number "
            sSQL += "WHERE i.ship_date BETWEEN N'" & Format(Me.dtpStartDate.Value, "MM/dd/yyyy") & "' AND N'" & Format(Me.dtpEndDate.Value, "MM/dd/yyyy") & "' AND "
            sSQL += "invoice_type = N'B' "
            sSQL += "ORDER BY i.customer_no, "
            sSQL += "i.ship_date, "
            sSQL += "r.railcar_number"
            drSystem = modGeneral.drRunSQL(sSQL, CommandType.Text)
            Do While drSystem.Read
                oWorksheet.Cells(iRowCount, 1).Value = drSystem("ship_date")
                oWorksheet.Cells(iRowCount, 2).Value = drSystem("customer_no")
                oWorksheet.Cells(iRowCount, 3).Value = drSystem("invoice_number")
                oWorksheet.Cells(iRowCount, 4).Value = drSystem("customer_purchase_order_no")
                oWorksheet.Cells(iRowCount, 5).Value = drSystem("railcar_number")
                oWorksheet.Cells(iRowCount, 6).Value = drSystem("weight")
                oWorksheet.Cells(iRowCount, 7).Value = drSystem("total")
                oWorksheet.Cells(iRowCount, 8).Value = drSystem("member_purchase_order_no")
                iRowCount += 1
            Loop
            drSystem.Close()
            With oWorksheet.Range("A1", "J1")
                .Font.Bold = True
                .EntireColumn.AutoFit()
            End With
            oWorksheet.Range("D1").EntireColumn.HorizontalAlignment = Excel.Constants.xlLeft
            With oWorksheet.Range("F1")
                .EntireColumn.HorizontalAlignment = Excel.Constants.xlRight
                .EntireColumn.NumberFormat = "#,##0.00_);(#,##0.00)"
            End With
            With oWorksheet.Range("G1")
                .EntireColumn.HorizontalAlignment = Excel.Constants.xlRight
                .EntireColumn.NumberFormat = "#,##0.00_);(#,##0.00)"
            End With
            oWorkbook.SaveAs(Me.txtExportLocation.Text & "\sales-b.xlsx")
        End If
        oExcel.Visible = True

        GC.Collect()
        GC.WaitForPendingFinalizers()
        System.Runtime.InteropServices.Marshal.ReleaseComObject(oWorksheet) : oWorksheet = Nothing
        System.Runtime.InteropServices.Marshal.ReleaseComObject(oWorkbook) : oWorkbook = Nothing
        System.Runtime.InteropServices.Marshal.ReleaseComObject(oExcel) : oExcel = Nothing
    Catch ex As Exception
        RaiseError("", Me.Name & "." & System.Reflection.MethodBase.GetCurrentMethod().Name, Err.Number, Err.Description)
    Finally
        If Not drSystem Is Nothing Then
            If Not drSystem.IsClosed Then drSystem.Close()
        End If
    End Try

    Me.lblStatus.Text = ""
    Me.Cursor = Cursors.Default

Answer 1

使用后需要处理并释放excel对象。

我使用的简单代码，即使在任务管理器中也可以关闭excel：

Private Sub releaseObject(ByVal obj As Object) Try System.Runtime.InteropServices.Marshal.ReleaseComObject(obj) obj = Nothing Catch ex As Exception obj = Nothing Finally GC.Collect() End Try End Sub

它适用于我的应用程序

Answer 2

不幸的是，在interop的情况下，将变量设置为空不会释放excel进程句柄...但是如果你明确地释放了你已经实例化的每个excel com对象引用，那么一旦excel被释放，这个进程不应该被挂起由用户关闭。当我运行以下代码并关闭excel时，该进程不再挂起（我遗漏了oRange，因为它仍然设置为空，并释放一个没有引发异常的对象）：

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim oExcel As Excel.Application = Nothing
        Dim oWorkbook As Excel.Workbook = Nothing
        Dim oWorksheet As Excel.Worksheet = Nothing

        oExcel = CreateObject("Excel.Application")
        oExcel.DisplayAlerts = False
        oExcel.Visible = False

        oWorkbook = oExcel.Workbooks.Add
        oWorksheet = oWorkbook.ActiveSheet
        'Populate, format, etc.
        'oWorkbook.SaveAs(Me.txtExportLocation.Text & "\sales.xlsx")

        oExcel.Visible = True

        System.Runtime.InteropServices.Marshal.ReleaseComObject(oWorksheet)
        System.Runtime.InteropServices.Marshal.ReleaseComObject(oWorkbook)
        System.Runtime.InteropServices.Marshal.ReleaseComObject(oExcel)
        Me.Close()
    End Sub
End Class