问题描述
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我正在从按钮单击事件中调用以下方法,以将数据表导出到excel。导出完成后,excel应用程序对象将退出,释放并没有分配任何内容。但实际上,除非关闭整个应用程序,否则它不会被释放并保持活动状态。因此,每次单击按钮进行导出时,新的excel应用程序对象都会继续运行。我该如何解决?请帮忙。问候。
如果未使用下面方法中的两行,则不会发生此问题。但是我不能忽略它们,因为它们确实是必需的。检查*标记的行。
\'\'\' <summary>
\'\'\' Exports data from a datatable to excel.
\'\'\' </summary>
Friend Shared Sub ExportToExcel(ByVal dtbl As DataTable)
Dim exa As Excel.Application = nothing
Dim wkb As Excel.Workbook = nothing
Dim wks As Excel.Worksheet = nothing
Dim intColIndex,intRowIndex As Integer
intColIndex = 0 : intRowIndex = 2
Try
exa = New Excel.Application
exa.SheetsInNewWorkbook = 1
wkb = exa.Workbooks.Add
wks = wkb.ActiveSheet
For intColIndex = 1 To dtbl.Columns.Count
wks.Cells(1,intColIndex) = dtbl.Columns(intColIndex - 1).ColumnName
Next
For Each row As DaTarow In dtbl.Rows
For intColIndex = 1 To dtbl.Columns.Count
wks.Cells(intRowIndex,intColIndex) = row(intColIndex - 1)
Next
intRowIndex += 1
Next
For intColIndex = 1 To dtbl.Columns.Count
wks.Range(wks.Cells(1,intColIndex),wks.Cells(1,intColIndex)).Font.Bold = True
wks.Range(wks.Cells(1,intColIndex)).Font.Underline = True
Next
\'***** The problem doesn\'t occur if the following two lines are not used *****
wks.Range(wks.Cells(1,1),wks.Cells(dtbl.Rows.Count + 1,dtbl.Columns.Count)).Columns.WrapText = False
wks.Range(wks.Cells(1,dtbl.Columns.Count)).Columns.AutoFit()
\'*****************************************************************************
exa.Visible = True
exa.UserControl = True
If Not exa Is nothing Then exa.Quit()
System.Runtime.InteropServices.Marshal.ReleaseComObject(wks)
wks = nothing
System.Runtime.InteropServices.Marshal.ReleaseComObject(wkb)
wkb = nothing
System.Runtime.InteropServices.Marshal.ReleaseComObject(exa)
exa = nothing
Catch ex As Exception
wks = nothing
wkb = nothing
exa = nothing
MsgBox(\"The following error has occurred:\" & vbCrLf & ex.Message,MsgBoxStyle.Critical,\"Error\")
Finally
GC.Collect()
End Try
End Sub
解决方法
这是您的解决方案。
Never use 2 dots with com objects.
Range().Columns
创建不会释放的临时变量。
如何正确清理Excel互操作对象?
http://www.velocityreviews.com/forums/showpost.php?s=f87f0674feda4442dcbd40019cbca65b&p=528575&postcount=2
,避免使用interop编写excel文件,通常会遇到这些类型的问题。
一种首选的方法是使用各种excel api之一来生成文件,例如excelpackage,NPOI或专有文档。另外,用户不必安装excel(他们可以使用开放式办公室等)