Question

我尝试创建一个我想要使用excel实例的类，我想按需退出该excel实例（如this answer中所述。仍然能够debug it properly我分开了垃圾收集方式如下：

Imports Excel = Microsoft.Office.Interop.Excel

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim xlsInst As New ExcelInst
        GC.Collect()
        GC.WaitForPendingFinalizers()
    End Sub End Class

Public Class ExcelInst
    Sub New()
        Dim myxlApp As New Excel.Application
        Dim myxlWb As Excel.Workbook
        '~~> Add a new Workbook
        myxlWb = myxlApp.Workbooks.Add
        '~~> Display Excel
        myxlApp.Visible = True
        myxlApp.Quit()
    End Sub End Class

一旦加载表单，观察任务管理器excel实例就会正常退出。但我对班级不满意。因为我想拥有myxlApp和myxlWB的私有变量。但如果我把班级改为

Public Class ExcelInst
    Private myxlApp As New Excel.Application
    Private myxlWb As Excel.Workbook

    Sub New()
        '~~> Add a new Workbook
        myxlWb = myxlApp.Workbooks.Add
        '~~> Display Excel
        myxlApp.Visible = True
        myxlApp.Quit()
    End Sub
End Class

excel不再需要关闭了。 Doese有谁知道为什么第一个片段有效（根据我的要求而第二个不是？

Answer 1

我认为既然你在GC.Collect之前仍然有对xlsInst的引用，并且该对象包含对excel的引用，那么GC将不会收集。尝试在Collect之前执行xlsInst = Nothing，也可以将类中的变量设置为空。

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Dim xlsInst As New ExcelInst
    xlsInst = Nothing
    GC.Collect()
    GC.WaitForPendingFinalizers()
End Sub End Class

Public Class ExcelInst
    Private myxlApp As New Excel.Application
    Private myxlWb As Excel.Workbook

    Sub New()
        '~~> Add a new Workbook
        myxlWb = myxlApp.Workbooks.Add
        '~~> Display Excel
        myxlApp.Visible = True
        myxlApp.Quit()

        myxlApp = Nothing
        myxlWb = Nothing
    End Sub
End Class

我必须补充一点，我觉得将这个逻辑放在New（）中很奇怪。我建议将它放在静态函数中，或者使用.ProcessExcel（）或.CloseExcel（）函数。

根据需要退出excel实例作为类成员

1 个答案: