.NET OpenXML性能问题

Question

我试图使用OpenXML从ASP.NET Web服务器写出一个Excel文件.我有大约2100条记录,大约需要20-30秒才能完成.我能以任何方式加快速度吗？从db中检索2100行只需要几分之一秒.不知道为什么在内存中操作它们会花费更长的时间.

注意:ExcelWriter是我们的自定义类,但它的所有方法都直接来自此链接中的代码,http://msdn.microsoft.com/en-us/library/cc861607.aspx

   public static MemoryStream CreateThingReport(List<Thing> things, MemoryStream template)
    {
        SpreadsheetDocument spreadsheet = SpreadsheetDocument.Open(template, true);
        WorksheetPart workSheetPart = spreadsheet.WorkbookPart.WorksheetParts.First();

        SharedStringTablePart sharedStringPart = spreadsheet.WorkbookPart.GetPartsOfType<SharedStringTablePart>().First();

        Cell cell = null;
        int index = 0;

        //create cell formatting for header text
        Alignment wrappedAlignment = new Alignment { WrapText = true };
               uint rowOffset = 2;

  foreach (Thing t in things)
        {
            //Received Date
            cell = ExcelWriter.InsertCellIntoWorksheet("A", rowOffset, workSheetPart);
            index = ExcelWriter.InsertSharedStringItem(t.CreateDate.ToShortDateString(), sharedStringPart);
            cell.CellValue = new CellValue(index.ToString());
            cell.DataType = new DocumentFormat.OpenXml.EnumValue<CellValues>(CellValues.SharedString);

            //Car Part Name
            cell = ExcelWriter.InsertCellIntoWorksheet("B", rowOffset, workSheetPart);
            index = ExcelWriter.InsertSharedStringItem(t.CarPart.Name, sharedStringPart);
            cell.CellValue = new CellValue(index.ToString());
            cell.DataType = new DocumentFormat.OpenXml.EnumValue<CellValues>(CellValues.SharedString);

  rowOffset++; 
   }

 workSheetPart.Worksheet.Save();

        spreadsheet.WorkbookPart.Workbook.Save();
        spreadsheet.Close();

        return template;

Answer 1

因此,看起来MSDN社区文档中的某些人遇到了类似的性能影响.下面的代码非常低效.有人建议使用哈希表.

对于我们的解决方案,我们只是完全删除了共享字符串的插入,并在下载时间从1:03秒到0:03秒.

//Old: (1:03)
            cell = ExcelWriter.InsertCellIntoWorksheet("A", rowOffset, workSheetPart);
            index = ExcelWriter.InsertSharedStringItem(thing.CreateDate.ToShortDateString(), sharedStringPart);
            cell.CellValue = new CellValue(index.ToString());
            cell.DataType = new DocumentFormat.OpenXml.EnumValue<CellValues>(CellValues.SharedString);

 //New: (0:03)
             cell = ExcelWriter.InsertCellIntoWorksheet("A", rowOffset, workSheetPart);
             cell.CellValue = new CellValue(thing.CreateDate.ToShortDateString());
              cell.DataType = new DocumentFormat.OpenXml.EnumValue<CellValues>(CellValues.String);

MSDN Docs(缓慢的解决方案,他们应该使用哈希表)

      private static int InsertSharedStringItem(string text, SharedStringTablePart         shareStringPart)
  {
// If the part does not contain a SharedStringTable, create one.
if (shareStringPart.SharedStringTable == null)
{
    shareStringPart.SharedStringTable = new SharedStringTable();
}

int i = 0;

// Iterate through all the items in the SharedStringTable. If the text already exists, return its index.
foreach (SharedStringItem item in shareStringPart.SharedStringTable.Elements<SharedStringItem>())
{
    if (item.InnerText == text)
    {
        return i;
    }

    i++;
}

// The text does not exist in the part. Create the SharedStringItem and return its index.
shareStringPart.SharedStringTable.AppendChild(new SharedStringItem(new DocumentFormat.OpenXml.Spreadsheet.Text(text)));
shareStringPart.SharedStringTable.Save();

return i;
 }  

Answer 2

@互联网

请注意,String数据类型实际上是用于公式,因为文本应该使用InlineString.请参见17.18.11 ST_CellType(单元格类型):

• inlineStr(Inline String) - 包含(内联)丰富字符串的单元格,即不在共享字符串表中的字符串.如果使用此单元格类型,则单元格值位于is元素而不是单元格中的v元素(c元素).
• str(String) - 包含公式字符串的单元格.