（1）OleDB方式
優點：將Excel直接當做數據源處理，通過SQL直接讀取內容，讀取速度較快。
缺點：讀取數據方式不夠靈活，無法直接讀取某一個單元格，只有將整個Sheet頁讀取出來後（結果為Datatable）再在Datatable中根據行列數來獲取指定的值。
當Excel數據量很大時。會非常占用內存，當內存不夠時會拋出內存溢出的異常。
讀取代碼如下：
1: public DataTable GetExcelTableByOleDB(string strExcelPath, string tableName)
2: {
3: try
4: {
5: DataTable dtExcel = new DataTable();
6: //數據表
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);//填充數據
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，這代表第一行是標題，不做為數據使用（但是我在實際使用中，如果第一行存在復雜數值，那麼讀取得到的Datatable列標題會自動設置為F1、F2等方式命名，與實際應用不符，所以當時是通過HDR=No方式將所有內容讀取到Datatable中，然後手動將第一行設置成標題的）；IMEX ( IMport EXport mode )設置
IMEX 有三種模式：
0 is Export mode
1 is Import mode
2 is Linked mode (full update capabilities)
我這裡特別要說明的就是 IMEX 參數了，因為不同的模式代表著不同的讀寫行為：
當 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 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 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。
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另外，讀取Excel2007版本的文件時，版本應該從8.0改為12.0，同時驅動不能再用Jet，而應該用ACE。負責會造成“找不到可安裝的 ISAM”的錯誤。
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在網上還發現采用這種方式存在取出的Sheet表的個數多於實際Excel表中的Sheet表個數的情況，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後綴的， 這是XL用來記錄Filter范圍的。
對於第一點比較簡單， 刪除已有命名管理器中的內容即可；第二點處理起來比較麻煩， Filter刪除後這些名稱依然保留著，簡單的做法是新增Sheet然後將原Sheet Copy進去。但實際情況並不能為每個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一般情況最後一個字符都不會是$。如果SheetName有一些特殊符號，讀取出來的SheetName會自動加上單引號。比如在Excel中將SheetName編輯成MySheet(1)，此時讀取出來的SheetName就為：'MySheet(1)$'，所以判斷最後一個字符是不是$之前最好過濾一下單引號。
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（2）Com組件的方式（通過添加 Microsoft.Office.Interop.Excel引用實現）
優點：能夠非常靈活的讀取Excel中的數據，用戶可以靈活的調用各種函數進行處理。
缺點：基於單元格的處理，讀取速度較慢，對於數據量較大的文件最好不要使用此種方式讀取。
需要添加相應的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，還需要服務器機子已安裝了Excel，有時候還需要為配置IIS權限。
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: //將數據讀入到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: //負責列頭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: //將數據讀入到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: //將數據讀入到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: //負責列頭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
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: //數據大於500條，使用多進程進行讀取數據
131: if (iRowCount - 1 > 500)
132: {
133: //開始多線程讀取數據
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: //主線程讀取剩余數據
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據追加至 dt1 後面
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: //將數據讀入到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: }
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（3）NPOI方式讀取Excel（此方法未經過測試）
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 或者相應環境的機器上對 WORD/EXCEL 文檔進行讀寫。
優點：讀取Excel速度較快，讀取方式操作靈活性
缺點：需要下載相應的插件並添加到系統引用當中。
1: /// <summary>
2: /// 將excel中的數據導入到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; //一行最後一個cell的編號 即總的列數
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: //最後一列的標號
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; //沒有數據的行默認是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，沒有數據的單元格都默認是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: }
部分內容參考http://www.cnblogs.com/Tsong/archive/2013/02/21/2920941.html。特此說明！
