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。

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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。

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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。

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（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: }

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（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！