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C#讀取Excel的三種方式以及比較

2018-01-04

C#讀取Excel的三種方式以及比較
（1）OleDB方式
優(yōu)點：將Excel直接當(dāng)做數(shù)據(jù)源處理，通過SQL直接讀取內(nèi)容，讀取速度較快。
缺點：讀取數(shù)據(jù)方式不夠靈活，無法直接讀取某一個單元格，只有將整個Sheet頁讀取出來后（結(jié)果為Datatable）再在Datatable中根據(jù)行列數(shù)來獲取指定的值。

當(dāng)Excel數(shù)據(jù)量很大時。會非常占用內(nèi)存，當(dāng)內(nèi)存不夠時會拋出內(nèi)存溢出的異常。
讀取代碼如下：
   1: public DataTable GetExcelTableByOleDB(string strExcelPath, string tableName)

   2: {

   3:     try

   4:     {

   5:         DataTable dtExcel = new DataTable();

   6:         //數(shù)據(jù)表

   7:         DataSet ds = new DataSet();

   8:         //獲取文件擴展名

   9:         string strExtension = System.IO.Path.GetExtension(strExcelPath);

10:         string strFileName = System.IO.Path.GetFileName(strExcelPath);

11:         //Excel的連接

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:         //獲取Excel中所有Sheet表的信息

31:         //System.Data.DataTable schemaTable = objConn.GetOleDbSchemaTable(System.Data.OleDb.OleDbSchemaGuid.Tables, null);

32:         //獲取Excel的第一個Sheet表名

33:         //string tableName = schemaTable.Rows[0][2].ToString().Trim();

34:         string strSql = "select * from [" + tableName + "]";

35:         //獲取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);//填充數(shù)據(jù)

39:         objConn.Close();

40:         //dtExcel即為excel文件中指定表中存儲的信息

41:         dtExcel = ds.Tables[tableName];

42:         return dtExcel;

43:     }

44:     catch

45:     {

46:         return null;

47:     }

48: }

下面說明一下連接字符串

        HDR=Yes，這代表第一行是標(biāo)題，不做為數(shù)據(jù)使用（但是我在實際使用中，如果第一行存在復(fù)雜數(shù)值，那么讀取得到的Datatable列標(biāo)題會自動設(shè)置為F1、F2等方式命名，與實際應(yīng)用不符，所以當(dāng)時是通過HDR=No方式將所有內(nèi)容讀取到Datatable中，然后手動將第一行設(shè)置成標(biāo)題的）；IMEX ( IMport EXport mode )設(shè)置
IMEX 有三種模式：
0 is Export mode
1 is Import mode
2 is Linked mode (full update capabilities)
我這里特別要說明的就是 IMEX 參數(shù)了，因為不同的模式代表著不同的讀寫行為：
當(dāng) IMEX=0 時為“匯出模式”，這個模式開啟的 Excel 檔案只能用來做“寫入”用途。
當(dāng) IMEX=1 時為“匯入模式”，這個模式開啟的 Excel 檔案只能用來做“讀取”用途。
當(dāng) IMEX=2 時為“鏈接模式”，這個模式開啟的 Excel 檔案可同時支援“讀取”與“寫入”用途。

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

另外，讀取Excel2007版本的文件時，版本應(yīng)該從8.0改為12.0，同時驅(qū)動不能再用Jet，而應(yīng)該用ACE。負(fù)責(zé)會造成“找不到可安裝的 ISAM”的錯誤。

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

在網(wǎng)上還發(fā)現(xiàn)采用這種方式存在取出的Sheet表的個數(shù)多于實際Excel表中的Sheet表個數(shù)的情況，其原因有二：

1. 取出的名稱中，包括了XL命名管理器中的名稱（參見XL2007的公式--命名管理器，快捷鍵Crtl+F3）；

2. 取出的名稱中，包括了FilterDatabase后綴的，這是XL用來記錄Filter范圍的。

對于第一點比較簡單，刪除已有命名管理器中的內(nèi)容即可；第二點處理起來比較麻煩， Filter刪除后這些名稱依然保留著，簡單的做法是新增Sheet然后將原Sheet Copy進去。但實際情況并不能為每個Excel做以上檢查。下面給出了過濾的方案。（此問題我們有驗證過，大家自己驗證一下吧）

   1: //objConn為讀取Excel的鏈接，下面通過過濾來獲取有效的Sheet頁名稱集合

   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:           //過濾無效SheetName完畢....

10:           continue;

11:       }

12:       if (lstSheetNames != null && !lstSheetNames.Contains(strSheetName))

13:           lstSheetNames.Add(strSheetName);

14:   }

因為讀取出來無效SheetName一般情況最后一個字符都不會是$。如果SheetName有一些特殊符號，讀取出來的SheetName會自動加上單引號。比如在Excel中將SheetName編輯成MySheet(1)，此時讀取出來的SheetName就為：'MySheet(1)$'，所以判斷最后一個字符是不是$之前最好過濾一下單引號。

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

（2）Com組件的方式（通過添加 Microsoft.Office.Interop.Excel引用實現(xiàn)）

優(yōu)點：能夠非常靈活的讀取Excel中的數(shù)據(jù)，用戶可以靈活的調(diào)用各種函數(shù)進行處理。

缺點：基于單元格的處理，讀取速度較慢，對于數(shù)據(jù)量較大的文件最好不要使用此種方式讀取。

           需要添加相應(yīng)的DLL引用，必須存在此引用才可使用，如果是Web站點部署在IIS上時，還需要服務(wù)器機子已安裝了Excel，有時候還需要為配置IIS權(quán)限。

讀取代碼如下：

   1: private Stopwatch wath = new Stopwatch();

   2: /// <summary>

   3: /// 使用COM讀取Excel

   4: /// </summary>

   5: /// <param name="excelFilePath">路徑</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:         //將數(shù)據(jù)讀入到DataTable中——Start

24:         sheets = workbook.Worksheets;

25:         Excel.Worksheet worksheet = (Excel.Worksheet)sheets.get_Item(1);//讀取第一張表

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:         //負(fù)責(zé)列頭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:         //將數(shù)據(jù)讀入到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，多線程讀取Excel（1 主線程、4 副線程）

81: /// </summary>

82: /// <param name="excelFilePath">路徑</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:         //將數(shù)據(jù)讀入到DataTable中——Start

101:         sheets = workbook.Worksheets;

102:         Excel.Worksheet worksheet = (Excel.Worksheet)sheets.get_Item(1);//讀取第一張表

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:         //負(fù)責(zé)列頭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:             //判斷列名是否重復(fù)

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:         //數(shù)據(jù)大于500條，使用多進程進行讀取數(shù)據(jù)

131:         if (iRowCount - 1 > 500)

132:         {

133:             //開始多線程讀取數(shù)據(jù)

134:             //新建線程

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，保證第一個讀取 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:             //主線程讀取剩余數(shù)據(jù)

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:             //將多個線程讀取出來的數(shù)據(jù)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:         //將數(shù)據(jù)讀入到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方式讀取Excel（此方法未經(jīng)過測試）

NPOI 是 POI 項目的 .NET 版本。POI是一個開源的Java讀寫Excel、WORD等微軟OLE2組件文檔的項目。使用 NPOI 你就可以在沒有安裝 Office 或者相應(yīng)環(huán)境的機器上對 WORD/EXCEL 文檔進行讀寫。

優(yōu)點：讀取Excel速度較快，讀取方式操作靈活性

缺點：需要下載相應(yīng)的插件并添加到系統(tǒng)引用當(dāng)中。

   1: /// <summary>

   2: /// 將excel中的數(shù)據(jù)導(dǎo)入到DataTable中

   3: /// </summary>

   4: /// <param name="sheetName">excel工作薄sheet的名稱</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; //一行最后一個cell的編號即總的列數(shù)

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:             //最后一列的標(biāo)號

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; //沒有數(shù)據(jù)的行默認(rèn)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，沒有數(shù)據(jù)的單元格都默認(rèn)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: }