Interop Operations后Excel实例不会关闭

时间:2016-01-04 13:16:28

标签: c# excel interop

我通过组合一系列不同Excel工作簿的第一张表,在c#中构建一个新的Excel工作簿;随后我将新的工作簿导出为PDF。我做了这个工作,但是在方法结束时总是有一个Excel实例运行。

我讨论了here同样的问题,设置更简单,我可以解决更少的Excel对象使用GC.Collect命令。现在,这些都不起作用。

public void CombineWorkBooks()
    {
        Microsoft.Office.Interop.Excel.Application xlApp = new Microsoft.Office.Interop.Excel.Application();

        xlApp.DisplayAlerts = false;
        xlApp.Visible = false;

        Workbooks newBooks = null;
        Workbook newBook = null;
        Sheets newBookWorksheets = null;
        Worksheet defaultWorksheet = null;

        // Create a new workbook, comes with an empty default worksheet");
        newBooks = xlApp.Workbooks;

        newBook = newBooks.Add(XlWBATemplate.xlWBATWorksheet);
        newBookWorksheets = newBook.Worksheets;

        // get the reference for the empty default worksheet
        if (newBookWorksheets.Count > 0)
        {
            defaultWorksheet = newBookWorksheets[1] as Worksheet;
        }

        // loop through every line in Gridview and get the path' to each Workbook
        foreach (GridViewRow row in CertificadosPresion.Rows)
        {
            string path = row.Cells[0].Text;
            string CertName = CertificadosPresion.DataKeys[row.RowIndex].Value.ToString();

            Workbook childBook = null;
            Sheets childSheets = null;

            // Excel of each line in Gridview
            childBook = newBooks.Open(path,Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
            childSheets = childBook.Worksheets;

            if (childSheets != null)
            {
                // Build a new Worksheet
                Worksheet sheetToCopy = null;

                // Only first Worksheet of the Workbook belonging to that line
                sheetToCopy = childSheets[1] as Worksheet;
                if (sheetToCopy != null)
                {
                    // Assign the Certificate Name to the new Worksheet 
                    sheetToCopy.Name = CertName;
                    // set PageSetup for the new Worksheet to be copied
                    sheetToCopy.PageSetup.Zoom = false;
                    sheetToCopy.PageSetup.FitToPagesWide = 1;
                    sheetToCopy.PageSetup.FitToPagesTall = 1;
                    sheetToCopy.PageSetup.PaperSize = Microsoft.Office.Interop.Excel.XlPaperSize.xlPaperA4;
                    // Copy that new Worksheet to the defaultWorksheet
                    sheetToCopy.Copy(defaultWorksheet, Type.Missing);
                }
                System.Runtime.InteropServices.Marshal.ReleaseComObject(sheetToCopy);
                childBook.Close(false, Type.Missing, Type.Missing);

            }
            System.Runtime.InteropServices.Marshal.ReleaseComObject(childSheets);
            System.Runtime.InteropServices.Marshal.ReleaseComObject(childBook);
        }

        //Delete the empty default worksheet
        if (defaultWorksheet != null) defaultWorksheet.Delete();

        //Export to PDF
        newBook.ExportAsFixedFormat(Microsoft.Office.Interop.Excel.XlFixedFormatType.xlTypePDF, @"C:\pdf\" + SALESID.Text + "_CertPres.pdf", 0, false, true);

        newBook.Close();
        newBooks.Close();
        xlApp.DisplayAlerts = true;
        DownloadFile(SALESID.Text);

        System.Runtime.InteropServices.Marshal.ReleaseComObject(defaultWorksheet);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(newBookWorksheets);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(newBook);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(newBooks);

        xlApp.Quit();
        System.Runtime.InteropServices.Marshal.ReleaseComObject(xlApp);

        GC.Collect();
        GC.WaitForPendingFinalizers();
    }
        protected void DownloadFile(string Salesid)
    {
        string path = @"c:\\pdf\" + Salesid + "_CertPres.pdf";
        byte[] bts = System.IO.File.ReadAllBytes(path);
        Response.Clear();
        Response.ClearHeaders();
        Response.AddHeader("Content-Type", "Application/octet-stream");
        Response.AddHeader("Content-Length", bts.Length.ToString());
        Response.AddHeader("Content-Disposition", "attachment; filename=" + Salesid + "_CertPres.pdf");
        Response.BinaryWrite(bts);
        Response.Flush();
        Response.End();
    }

问题必定与DownloadFile方法的调用有关。我取消了该调用,并且Excel进程已正确关闭。其中一些操作必须保持对其中一个COM对象的引用,以便它们无法关闭。通过调用" DownloadFile"在GarbageCollect之后的最后问题解决了。 (我不太清楚为什么)

3 个答案:

答案 0 :(得分:0)

我发现有时唯一有帮助的是“大锤方法”。杀死所有正在运行的Excel实例:

foreach (Process p in Process.GetProcessesByName("EXCEL"))
{
    try
    {
        p.Kill();
        p.WaitForExit();
    }
    catch
    {
        //Handle exception here
    }
}

答案 1 :(得分:0)

在我看来你没有清理过参考文献。可能类似于“双点规则”'问题 - 在我看来这是一个愚蠢的规则,因为你不能编写任何体面的代码,因为它难以跟踪。

您可以尝试使用COM引用的Marshal.ReleaseComObject,但仍然会遇到麻烦......

我的建议是尝试使用VSTO自动化Excel。这将代表您正确清除您的参考文献。

https://social.msdn.microsoft.com/Forums/vstudio/en-US/a12add6b-99ea-4677-8245-cd667101683e/vsto-and-office-objects-disposing

答案 2 :(得分:0)

在您的方法DownloadFile中,您可以调用

Response.End()

HttpResponse.End抛出异常(强调我的):

  

为了模仿ASP中End方法的行为,此方法尝试引发ThreadAbortException异常。如果此尝试成功,调用线程将被中止,[...]

此异常会中止您的线程。因此,所有ReleaseComObject,Excel.Quit,GC.Collect东西都不会被执行

解决方案:不要拨打Response.End。你可能不需要它。如果您需要,可能需要考虑替代mentioned in the documentation

  

此方法仅用于与ASP兼容,即与ASP.NET之前的基于COM的Web编程技术兼容。如果您想跳到EndRequest事件并向客户端发送响应,通常最好调用CompleteRequest。

     

[...]

     

CompleteRequest方法不会引发异常,并且可能会执行对CompleteRequest方法的调用后的代码

PS:使用Web应用程序中的Excel自动化not officially supported by Microsoft。对于将来的开发,您可能需要考虑使用第三方Excel库。