csharp read excel file get sheetName list

/// <summary>
         ///
         /// 塗聚文
         /// 20120803
         /// Geovin Du
         ///找到EXCEL的工作表名称 要考慮打開的文件的進程問題
         /// </summary>
         /// <param name="filename"></param>
         /// <param name="comboBox2"></param>
         /// <returns></returns>
         public static System.Data.DataTable getSheetName(string filename, ComboBox comboBox2)
         {
             System.Data.DataTable dtSheets = new System.Data.DataTable();
             try
             {

                 dtSheets.Columns.Add("id", typeof(int));
                 dtSheets.Columns.Add("SheetName", typeof(string));
                 object objOpt = Missing.Value;
                 Excel.Application excelApp = new Excel.Application();
                 excelApp.Workbooks.Open(filename, objOpt, objOpt, objOpt, objOpt, objOpt, true, objOpt, objOpt, true, objOpt, objOpt, objOpt, objOpt, objOpt);
                 for (int i = 0; i < excelApp.Workbooks[1].Worksheets.Count; i++)
                 {
                     Excel.Worksheet ws = (Excel.Worksheet)excelApp.Workbooks[1].Worksheets[i + 1];
                     string sSheetName = ws.Name;
                     dtSheets.Rows.Add(i, ws.Name);
                 }
                 comboBox2.DataSource = dtSheets;
                 comboBox2.DisplayMember = "SheetName";
                 comboBox2.ValueMember = "id";
                 comboBox2.AutoCompleteMode = AutoCompleteMode.Suggest;
                 comboBox2.AutoCompleteSource = AutoCompleteSource.ListItems;
                 KillExcelProceed();
                 Kill(excelApp);
             }
             catch (IOException ex)
             {
                 ex.Message.ToString();
             }
             return dtSheets;
         }
         /// <summary>
         ///
         /// 塗聚文 締友計算機信息技術有限公司
         /// 20120803
         /// Geovin Du
         /// </summary>
         /// <param name="filename"></param>
         /// <param name="comboBox2"></param>
         /// <returns></returns>
         public static System.Data.DataTable getGeovinDuSheetName(string filename, ComboBox comboBox2)
         {
             System.Data.DataTable dtSheets = new System.Data.DataTable();

             try
             {

                 dtSheets.Columns.Add("id", typeof(int));
                 dtSheets.Columns.Add("SheetName", typeof(string));
                 string connectionString = String.Format(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=""Excel 8.0;HDR=YES;IMEX=1;""", filename); //高版本用：Microsoft.ACE.OLEDB.12.0
                 DbProviderFactory factory = DbProviderFactories.GetFactory("System.Data.OleDb");
                 DbConnection connection = factory.CreateConnection();
                 connection.ConnectionString = connectionString;
                 connection.Open();
                 DataTable tbl = connection.GetSchema("Tables");
                 connection.Close();
                 int i = 0;
                 foreach (DataRow row in tbl.Rows)
                 {
                     string sheetName = (string)row["TABLE_NAME"];
                     if (sheetName.EndsWith("$"))
                     {
                         sheetName = sheetName.Substring(0, sheetName.Length - 1);
                     }
                     //繁體系統需要此操作，簡體的不需要也可以
                     sheetName = sheetName.Replace("$", "");
                     sheetName = sheetName.Replace("'", "");
                     dtSheets.Rows.Add(i,sheetName.Replace("$", ""));
                     i++;
                 }
                 comboBox2.DataSource = dtSheets;
                 comboBox2.DisplayMember = "SheetName";
                 comboBox2.ValueMember = "id";
                 comboBox2.AutoCompleteMode = AutoCompleteMode.Suggest;
                 comboBox2.AutoCompleteSource = AutoCompleteSource.ListItems;

                 return dtSheets;
             }
             catch (IOException ex)
             {
                 ex.Message.ToString();
                 return null;
             }

         }