閱讀一個大型的開放式XML電子表格

Question

我需要使用openxml庫來讀取（和解析）大型電子表格文件（20-50MB），並且似乎沒有辦法一次一個地流化一行來解析。

我一直髮生內存不足異常，因爲它似乎只要我嘗試訪問一行（或迭代）整個行內容被加載（100K +行）。

每個呼叫的

，是否Elements.Where（與查詢） 或後代（）似乎加載整個行集

是有辦法流或者只是一次讀取的行？

thx

Answer 1

我找到了答案。如果您在工作表部分使用OpenXmlReader，則可以迭代並有效延遲加載遇到的元素。

OpenXmlReader oxr = OpenXmlReader.Create(worksheetPart); 

找

ElementType == typeof(SheetData) 

並加載行（懶惰）

Row row = (Row)oxr.LoadCurrentElement(); 

Answer 2

做openxml庫使用dom還是sax模型？通常你必須將整個文檔一次存儲在內存中，但使用sax時，可以在事件發生時將它們串起來。

Answer 3

下面是讀取較大的Excel與多張紙利用SAX方法文件的代碼：

public static DataTable ReadIntoDatatableFromExcel(string newFilePath) 
     { 
      /*Creating a table with 20 columns*/ 
      var dt = CreateProviderRvenueSharingTable(); 

      try 
      { 
       /*using stream so that if excel file is in another process then it can read without error*/ 
       using (Stream stream = new FileStream(newFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)) 
       { 
        using (SpreadsheetDocument spreadsheetDocument = SpreadsheetDocument.Open(stream, false)) 
        { 
         var workbookPart = spreadsheetDocument.WorkbookPart; 
         var workbook = workbookPart.Workbook; 

         /*get only unhide tabs*/ 
         var sheets = workbook.Descendants<Sheet>().Where(e => e.State == null); 

         foreach (var sheet in sheets) 
         { 
          var worksheetPart = (WorksheetPart)workbookPart.GetPartById(sheet.Id); 

          /*Remove empty sheets*/ 
          List<Row> rows = worksheetPart.Worksheet.Elements<SheetData>().First().Elements<Row>() 
           .Where(r => r.InnerText != string.Empty).ToList(); 

          if (rows.Count > 1) 
          { 
           OpenXmlReader reader = OpenXmlReader.Create(worksheetPart); 

           int i = 0; 
           int BTR = 0;/*Break the reader while empty rows are found*/ 

           while (reader.Read()) 
           { 
            if (reader.ElementType == typeof(Row)) 
            { 
             /*ignoring first row with headers and check if data is there after header*/ 
             if (i < 2) 
             { 
              i++; 
              continue; 
             } 

             reader.ReadFirstChild(); 

             DataRow row = dt.NewRow(); 

             int CN = 0; 

             if (reader.ElementType == typeof(Cell)) 
             { 
              do 
              { 
               Cell c = (Cell)reader.LoadCurrentElement(); 

               /*reader skipping blank cells so data is getting worng in datatable's rows according to header*/ 
               if (CN != 0) 
               { 
                int cellColumnIndex = 
                 ExcelHelper.GetColumnIndexFromName(
                  ExcelHelper.GetColumnName(c.CellReference)); 

                if (cellColumnIndex < 20 && CN < cellColumnIndex - 1) 
                { 
                 do 
                 { 
                  row[CN] = string.Empty; 
                  CN++; 
                 } while (CN < cellColumnIndex - 1); 
                } 
               } 

               /*stopping execution if first cell does not have any value which means empty row*/ 
               if (CN == 0 && c.DataType == null && c.CellValue == null) 
               { 
                BTR++; 
                break; 
               } 

               string cellValue = GetCellValue(c, workbookPart); 
               row[CN] = cellValue; 
               CN++; 

               /*if any text exists after T column (index 20) then skip the reader*/ 
               if (CN == 20) 
               { 
                break; 
               } 
              } while (reader.ReadNextSibling()); 
             } 

             /*reader skipping blank cells so fill the array upto 19 index*/ 
             while (CN != 0 && CN < 20) 
             { 
              row[CN] = string.Empty; 
              CN++; 
             } 

             if (CN == 20) 
             { 
              dt.Rows.Add(row); 
             } 
            } 
            /*escaping empty rows below data filled rows after checking 5 times */ 
            if (BTR > 5) 
             break; 
           } 
           reader.Close(); 
          }        
         } 
        } 
       } 
      } 
      catch (Exception ex) 
      { 
       throw ex; 
      } 
      return dt; 
     } 

    private static string GetCellValue(Cell c, WorkbookPart workbookPart) 
     { 
      string cellValue = string.Empty; 
      if (c.DataType != null && c.DataType == CellValues.SharedString) 
      { 
       SharedStringItem ssi = 
        workbookPart.SharedStringTablePart.SharedStringTable 
         .Elements<SharedStringItem>() 
         .ElementAt(int.Parse(c.CellValue.InnerText)); 
       if (ssi.Text != null) 
       { 
        cellValue = ssi.Text.Text; 
       } 
      } 
      else 
      { 
       if (c.CellValue != null) 
       { 
        cellValue = c.CellValue.InnerText; 
       } 
      } 
      return cellValue; 
     } 

public static int GetColumnIndexFromName(string columnNameOrCellReference) 
     { 
      int columnIndex = 0; 
      int factor = 1; 
      for (int pos = columnNameOrCellReference.Length - 1; pos >= 0; pos--) // R to L 
      { 
       if (Char.IsLetter(columnNameOrCellReference[pos])) // for letters (columnName) 
       { 
        columnIndex += factor * ((columnNameOrCellReference[pos] - 'A') + 1); 
        factor *= 26; 
       } 
      } 
      return columnIndex; 
     } 

     public static string GetColumnName(string cellReference) 
     { 
      /* Advance from L to R until a number, then return 0 through previous position*/ 
      for (int lastCharPos = 0; lastCharPos <= 3; lastCharPos++) 
       if (Char.IsNumber(cellReference[lastCharPos])) 
        return cellReference.Substring(0, lastCharPos); 

      throw new ArgumentOutOfRangeException("cellReference"); 
     } 

代碼適用於： 1.從第一個升序讀取工作表 2.如果excel文件正在被另一個進程所訪問，OpenXML仍會讀取該文件。 3.該代碼讀取空白單元格 4.閱讀完成後跳過空行。 5.它在4秒內讀取5000行。