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C#读取Excel的三种形式以及比较

热度：379   发布时间：2016-05-05 05:09:57.0
C#读取Excel的三种方式以及比较

（1）OleDB方式

优点：将Excel直接当做数据源处理，通过SQL直接读取内容，读取速度较快。

缺点：读取数据方式不够灵活，无法直接读取某一个单元格，只有将整个Sheet页读取出来后（结果为Datatable）再在Datatable中根据行列数来获取指定的值。

           当Excel数据量很大时。会非常占用内存，当内存不够时会抛出内存溢出的异常。

读取代码如下：

   1: public DataTable GetExcelTableByOleDB(string strExcelPath, string tableName)
   2: {
   3:     try
   4:     {
   5:         DataTable dtExcel = new DataTable();
   6:         //数据表
   7:         DataSet ds = new DataSet();
   8:         //获取文件扩展名
   9:         string strExtension = System.IO.Path.GetExtension(strExcelPath);
  10:         string strFileName = System.IO.Path.GetFileName(strExcelPath);
  11:         //Excel的连接
  12:         OleDbConnection objConn = null;
  13:         switch (strExtension)
  14:         {
  15:             case ".xls":
  16:                 objConn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + strExcelPath + ";" + "Extended Properties=\"Excel 8.0;HDR=NO;IMEX=1;\"");
  17:                 break;
  18:             case ".xlsx":
  19:                 objConn = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + strExcelPath + ";" + "Extended Properties=\"Excel 12.0;HDR=NO;IMEX=1;\"");
  20:                 break;
  21:             default:
  22:                 objConn = null;
  23:                 break;
  24:         }
  25:         if (objConn == null)
  26:         {
  27:             return null;
  28:         }
  29:         objConn.Open();
  30:         //获取Excel中所有Sheet表的信息
  31:         //System.Data.DataTable schemaTable = objConn.GetOleDbSchemaTable(System.Data.OleDb.OleDbSchemaGuid.Tables, null);
  32:         //获取Excel的第一个Sheet表名
  33:         //string tableName = schemaTable.Rows[0][2].ToString().Trim();
  34:         string strSql = "select * from [" + tableName + "]";
  35:         //获取Excel指定Sheet表中的信息
  36:         OleDbCommand objCmd = new OleDbCommand(strSql, objConn);
  37:         OleDbDataAdapter myData = new OleDbDataAdapter(strSql, objConn);
  38:         myData.Fill(ds, tableName);//填充数据
  39:         objConn.Close();
  40:         //dtExcel即为excel文件中指定表中存储的信息
  41:         dtExcel = ds.Tables[tableName];
  42:         return dtExcel;
  43:     }
  44:     catch
  45:     {
  46:         return null;
  47:     }
  48: }

下面说明一下连接字符串

        HDR=Yes，这代表第一行是标题，不做为数据使用（但是我在实际使用中，如果第一行存在复杂数值，那么读取得到的Datatable列标题会自动设置为F1、F2等方式命名，与实际应用不符，所以当时是通过HDR=No方式将所有内容读取到Datatable中，然后手动将第一行设置成标题的）；IMEX ( IMport EXport mode )设置
IMEX 有三种模式：
0 is Export mode
1 is Import mode
2 is Linked mode (full update capabilities)
我这里特别要说明的就是 IMEX 参数了，因为不同的模式代表著不同的读写行为：
当 IMEX=0 时为“汇出模式”，这个模式开启的 Excel 档案只能用来做“写入”用途。
当 IMEX=1 时为“汇入模式”，这个模式开启的 Excel 档案只能用来做“读取”用途。
当 IMEX=2 时为“链接模式”，这个模式开启的 Excel 档案可同时支援“读取”与“写入”用途。

---------------------------------

另外，读取Excel2007版本的文件时，版本应该从8.0改为12.0，同时驱动不能再用Jet，而应该用ACE。负责会造成“找不到可安装的 ISAM”的错误。

---------------------------------

在网上还发现采用这种方式存在取出的Sheet表的个数多于实际Excel表中的Sheet表个数的情况，其原因有二：

1. 取出的名称中，包括了XL命名管理器中的名称（参见XL2007的公式--命名管理器， 快捷键Crtl+F3）；

2. 取出的名称中，包括了FilterDatabase后缀的， 这是XL用来记录Filter范围的。

对于第一点比较简单， 删除已有命名管理器中的内容即可；第二点处理起来比较麻烦， Filter删除后这些名称依然保留着，简单的做法是新增Sheet然后将原Sheet Copy进去。但实际情况并不能为每个Excel做以上检查。下面给出了过滤的方案。（此问题我们有验证过，大家自己验证一下吧）

   1: //objConn为读取Excel的链接，下面通过过滤来获取有效的Sheet页名称集合
   2:   System.Data.DataTable schemaTable = objConn.GetOleDbSchemaTable(System.Data.OleDb.OleDbSchemaGuid.Tables, null);
   3:   List<string> lstSheetNames = new List<string>();
   4:   for (int i = 0; i < schemaTable.Rows.Count; i++)
   5:   {
   6:       string strSheetName = (string)dtSheetName.Rows[i]["TABLE_NAME"];
   7:       if (strSheetName.Contains("$") && !strSheetName.Replace("'", "").EndsWith("$"))
   8:       {
   9:           //过滤无效SheetName完毕....
  10:           continue;
  11:       }
  12:       if (lstSheetNames != null && !lstSheetNames.Contains(strSheetName))
  13:           lstSheetNames.Add(strSheetName);
  14:   }

因为读取出来无效SheetName一般情况最后一个字符都不会是$。如果SheetName有一些特殊符号，读取出来的SheetName会自动加上单引号。比如在Excel中将SheetName编辑成MySheet(1)，此时读取出来的SheetName就为：'MySheet(1)$'，所以判断最后一个字符是不是$之前最好过滤一下单引号。

---------------------------------

（2）Com组件的方式（通过添加 Microsoft.Office.Interop.Excel引用实现）

优点：能够非常灵活的读取Excel中的数据，用户可以灵活的调用各种函数进行处理。

缺点：基于单元格的处理，读取速度较慢，对于数据量较大的文件最好不要使用此种方式读取。

           需要添加相应的DLL引用，必须存在此引用才可使用，如果是Web站点部署在IIS上时，还需要服务器机子已安装了Excel，有时候还需要为配置IIS权限。

读取代码如下：

   1: private Stopwatch wath = new Stopwatch();
   2: /// <summary>
   3: /// 使用COM读取Excel
   4: /// </summary>
   5: /// <param name="excelFilePath">路径</param>
   6: /// <returns>DataTabel</returns>
   7: public System.Data.DataTable GetExcelData(string excelFilePath)
   8: {
   9:     Excel.Application app = new Excel.Application();
  10:     Excel.Sheets sheets;
  11:     Excel.Workbook workbook = null;
  12:     object oMissiong = System.Reflection.Missing.Value;
  13:     System.Data.DataTable dt = new System.Data.DataTable();
  14:     wath.Start();
  15:     try
  16:     {
  17:         if (app == null)
  18:         {
  19:             return null;
  20:         }
  21:         workbook = app.Workbooks.Open(excelFilePath, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, 
  22:             oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong);
  23:         //将数据读入到DataTable中——Start   
  24:         sheets = workbook.Worksheets;
  25:         Excel.Worksheet worksheet = (Excel.Worksheet)sheets.get_Item(1);//读取第一张表
  26:         if (worksheet == null)
  27:             return null;
  28:         string cellContent;
  29:         int iRowCount = worksheet.UsedRange.Rows.Count;
  30:         int iColCount = worksheet.UsedRange.Columns.Count;
  31:         Excel.Range range;
  32:         //负责列头Start
  33:         DataColumn dc;
  34:         int ColumnID = 1;
  35:         range = (Excel.Range)worksheet.Cells[1, 1];
  36:         while (range.Text.ToString().Trim() != "")
  37:         {
  38:             dc = new DataColumn();
  39:             dc.DataType = System.Type.GetType("System.String");
  40:             dc.ColumnName = range.Text.ToString().Trim();
  41:             dt.Columns.Add(dc);
  42:  
  43:             range = (Excel.Range)worksheet.Cells[1, ++ColumnID];
  44:         }
  45:         //End
  46:         for (int iRow = 2; iRow <= iRowCount; iRow++)
  47:         {
  48:             DataRow dr = dt.NewRow();
  49:             for (int iCol = 1; iCol <= iColCount; iCol++)
  50:             {
  51:                 range = (Excel.Range)worksheet.Cells[iRow, iCol];
  52:                 cellContent = (range.Value2 == null) ? "" : range.Text.ToString();
  53:                     dr[iCol - 1] = cellContent;
  54:             }
  55:             dt.Rows.Add(dr);
  56:         }
  57:         wath.Stop();
  58:         TimeSpan ts = wath.Elapsed;
  59:         //将数据读入到DataTable中——End
  60:         return dt;
  61:     }
  62:     catch
  63:     {
  64:         return null;
  65:     }
  66:     finally
  67:     {
  68:         workbook.Close(false, oMissiong, oMissiong);
  69:         System.Runtime.InteropServices.Marshal.ReleaseComObject(workbook);
  70:         workbook = null;
  71:         app.Workbooks.Close();
  72:         app.Quit();
  73:         System.Runtime.InteropServices.Marshal.ReleaseComObject(app);
  74:         app = null;
  75:         GC.Collect();
  76:         GC.WaitForPendingFinalizers();
  77:     }
  78: }
  79: /// <summary>
  80: /// 使用COM，多线程读取Excel（1 主线程、4 副线程）
  81: /// </summary>
  82: /// <param name="excelFilePath">路径</param>
  83: /// <returns>DataTabel</returns>
  84: public System.Data.DataTable ThreadReadExcel(string excelFilePath)
  85: {
  86:     Excel.Application app = new Excel.Application();
  87:     Excel.Sheets sheets = null;
  88:     Excel.Workbook workbook = null;
  89:     object oMissiong = System.Reflection.Missing.Value;
  90:     System.Data.DataTable dt = new System.Data.DataTable();
  91:     wath.Start();
  92:     try
  93:     {
  94:         if (app == null)
  95:         {
  96:             return null;
  97:         }
  98:         workbook = app.Workbooks.Open(excelFilePath, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, 
  99:             oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong);
 100:         //将数据读入到DataTable中——Start   
 101:         sheets = workbook.Worksheets;
 102:         Excel.Worksheet worksheet = (Excel.Worksheet)sheets.get_Item(1);//读取第一张表
 103:         if (worksheet == null)
 104:             return null;
 105:         string cellContent;
 106:         int iRowCount = worksheet.UsedRange.Rows.Count;
 107:         int iColCount = worksheet.UsedRange.Columns.Count;
 108:         Excel.Range range;
 109:         //负责列头Start
 110:         DataColumn dc;
 111:         int ColumnID = 1;
 112:         range = (Excel.Range)worksheet.Cells[1, 1];
 113:         while (iColCount >= ColumnID)
 114:         {
 115:             dc = new DataColumn();
 116:             dc.DataType = System.Type.GetType("System.String");
 117:             string strNewColumnName = range.Text.ToString().Trim();
 118:             if (strNewColumnName.Length == 0) strNewColumnName = "_1";
 119:             //判断列名是否重复
 120:             for (int i = 1; i < ColumnID; i++)
 121:             {
 122:                 if (dt.Columns[i - 1].ColumnName == strNewColumnName)
 123:                     strNewColumnName = strNewColumnName + "_1";
 124:             }
 125:             dc.ColumnName = strNewColumnName;
 126:             dt.Columns.Add(dc);
 127:             range = (Excel.Range)worksheet.Cells[1, ++ColumnID];
 128:         }
 129:         //End
 130:         //数据大于500条，使用多进程进行读取数据
 131:         if (iRowCount - 1 > 500)
 132:         {
 133:             //开始多线程读取数据
 134:             //新建线程
 135:             int b2 = (iRowCount - 1) / 10;
 136:             DataTable dt1 = new DataTable("dt1");
 137:             dt1 = dt.Clone();
 138:             SheetOptions sheet1thread = new SheetOptions(worksheet, iColCount, 2, b2 + 1, dt1);
 139:             Thread othread1 = new Thread(new ThreadStart(sheet1thread.SheetToDataTable));
 140:             othread1.Start();
 141:             //阻塞 1 毫秒，保证第一个读取 dt1
 142:             Thread.Sleep(1);
 143:             DataTable dt2 = new DataTable("dt2");
 144:             dt2 = dt.Clone();
 145:             SheetOptions sheet2thread = new SheetOptions(worksheet, iColCount, b2 + 2, b2 * 2 + 1, dt2);
 146:             Thread othread2 = new Thread(new ThreadStart(sheet2thread.SheetToDataTable));
 147:             othread2.Start();
 148:             DataTable dt3 = new DataTable("dt3");
 149:             dt3 = dt.Clone();
 150:             SheetOptions sheet3thread = new SheetOptions(worksheet, iColCount, b2 * 2 + 2, b2 * 3 + 1, dt3);
 151:             Thread othread3 = new Thread(new ThreadStart(sheet3thread.SheetToDataTable));
 152:             othread3.Start();
 153:             DataTable dt4 = new DataTable("dt4");
 154:             dt4 = dt.Clone();
 155:             SheetOptions sheet4thread = new SheetOptions(worksheet, iColCount, b2 * 3 + 2, b2 * 4 + 1, dt4);
 156:             Thread othread4 = new Thread(new ThreadStart(sheet4thread.SheetToDataTable));
 157:             othread4.Start();
 158:             //主线程读取剩余数据
 159:             for (int iRow = b2 * 4 + 2; iRow <= iRowCount; iRow++)
 160:             {
 161:                 DataRow dr = dt.NewRow();
 162:                 for (int iCol = 1; iCol <= iColCount; iCol++)
 163:                 {
 164:                     range = (Excel.Range)worksheet.Cells[iRow, iCol];
 165:                     cellContent = (range.Value2 == null) ? "" : range.Text.ToString();
 166:                     dr[iCol - 1] = cellContent;
 167:                 }
 168:                 dt.Rows.Add(dr);
 169:             }
 170:             othread1.Join();
 171:             othread2.Join();
 172:             othread3.Join();
 173:             othread4.Join();
 174:             //将多个线程读取出来的数据追加至 dt1 后面
 175:             foreach (DataRow dr in dt.Rows)
 176:                 dt1.Rows.Add(dr.ItemArray);
 177:             dt.Clear();
 178:             dt.Dispose();
 179:             foreach (DataRow dr in dt2.Rows)
 180:                 dt1.Rows.Add(dr.ItemArray);
 181:             dt2.Clear();
 182:             dt2.Dispose();
 183:             foreach (DataRow dr in dt3.Rows)
 184:                 dt1.Rows.Add(dr.ItemArray);
 185:             dt3.Clear();
 186:             dt3.Dispose();
 187:             foreach (DataRow dr in dt4.Rows)
 188:                 dt1.Rows.Add(dr.ItemArray);
 189:             dt4.Clear();
 190:             dt4.Dispose();
 191:             return dt1;
 192:         }
 193:         else
 194:         {
 195:             for (int iRow = 2; iRow <= iRowCount; iRow++)
 196:             {
 197:                 DataRow dr = dt.NewRow();
 198:                 for (int iCol = 1; iCol <= iColCount; iCol++)
 199:                 {
 200:                     range = (Excel.Range)worksheet.Cells[iRow, iCol];
 201:                     cellContent = (range.Value2 == null) ? "" : range.Text.ToString();
 202:                     dr[iCol - 1] = cellContent;
 203:                 }
 204:                 dt.Rows.Add(dr);
 205:             }
 206:         }
 207:         wath.Stop();
 208:         TimeSpan ts = wath.Elapsed;
 209:         //将数据读入到DataTable中——End
 210:         return dt;
 211:     }
 212:     catch
 213:     {
 214:         return null;
 215:     }
 216:     finally
 217:     {
 218:         workbook.Close(false, oMissiong, oMissiong);
 219:         System.Runtime.InteropServices.Marshal.ReleaseComObject(workbook);
 220:         System.Runtime.InteropServices.Marshal.ReleaseComObject(sheets);
 221:         workbook = null;
 222:         app.Workbooks.Close();
 223:         app.Quit();
 224:         System.Runtime.InteropServices.Marshal.ReleaseComObject(app);
 225:         app = null;
 226:         GC.Collect();
 227:         GC.WaitForPendingFinalizers();
 228:     }
 229: }

---------------------------------

（3）NPOI方式读取Excel（此方法未经过测试）

NPOI 是 POI 项目的 .NET 版本。POI是一个开源的Java读写Excel、WORD等微软OLE2组件文档的项目。使用 NPOI 你就可以在没有安装 Office 或者相应环境的机器上对 WORD/EXCEL 文档进行读写。

优点：读取Excel速度较快，读取方式操作灵活性

缺点：需要下载相应的插件并添加到系统引用当中。

   1: /// <summary>
   2: /// 将excel中的数据导入到DataTable中
   3: /// </summary>
   4: /// <param name="sheetName">excel工作薄sheet的名称</param>
   5: /// <param name="isFirstRowColumn">第一行是否是DataTable的列名</param>
   6: /// <returns>返回的DataTable</returns>
   7: public DataTable ExcelToDataTable(string sheetName, bool isFirstRowColumn)
   8: {
   9:     ISheet sheet = null;
  10:     DataTable data = new DataTable();
  11:     int startRow = 0;
  12:     try
  13:     {
  14:         fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
  15:         if (fileName.IndexOf(".xlsx") > 0) // 2007版本
  16:             workbook = new XSSFWorkbook(fs);
  17:         else if (fileName.IndexOf(".xls") > 0) // 2003版本
  18:             workbook = new HSSFWorkbook(fs);
  19:         if (sheetName != null)
  20:         {
  21:             sheet = workbook.GetSheet(sheetName);
  22:         }
  23:         else
  24:         {
  25:             sheet = workbook.GetSheetAt(0);
  26:         }
  27:         if (sheet != null)
  28:         {
  29:             IRow firstRow = sheet.GetRow(0);
  30:             int cellCount = firstRow.LastCellNum; //一行最后一个cell的编号 即总的列数
  31:             if (isFirstRowColumn)
  32:             {
  33:                 for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
  34:                 {
  35:                     DataColumn column = new DataColumn(firstRow.GetCell(i).StringCellValue);
  36:                     data.Columns.Add(column);
  37:                 }
  38:                 startRow = sheet.FirstRowNum + 1;
  39:             }
  40:             else
  41:             {
  42:                 startRow = sheet.FirstRowNum;
  43:             }
  44:             //最后一列的标号
  45:             int rowCount = sheet.LastRowNum;
  46:             for (int i = startRow; i <= rowCount; ++i)
  47:             {
  48:                 IRow row = sheet.GetRow(i);
  49:                 if (row == null) continue; //没有数据的行默认是null　　　　　　　
  50:                 
  51:                 DataRow dataRow = data.NewRow();
  52:                 for (int j = row.FirstCellNum; j < cellCount; ++j)
  53:                 {
  54:                     if (row.GetCell(j) != null) //同理，没有数据的单元格都默认是null
  55:                         dataRow[j] = row.GetCell(j).ToString();
  56:                 }
  57:                 data.Rows.Add(dataRow);
  58:             }
  59:         }
  60:         return data;
  61:     }
  62:     catch (Exception ex)
  63:     {
  64:         Console.WriteLine("Exception: " + ex.Message);
  65:         return null;
  66:     }
  67: }

部分内容参考http://www.cnblogs.com/Tsong/archive/2013/02/21/2920941.html。特此说明！

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