C#、VSTO讀取Excel類

之前寫的類存在Excel進程不能結束的Bug，重寫ExcelReader類，類實例清理時Excel進程自動結束。

     class ExcelReader
     {
         // Excel Object
         public Application app;
         public Workbooks wbs;
         public Workbook wb;
         public Worksheet ws;
         public Range rng;

         private bool disposed = false;

         public ExcelReader()
         {
             // New Excel Application
             app = new Application
             {
                 Visible = false,
                 DisplayAlerts = false
             };
         }

         /// <summary>
         /// 關閉對象
         /// </summary>
         public void Close()
         {
             Dispose();
         }

         /// <summary>
         /// 清理對象
         /// </summary>
         public void Dispose()
         {
             Dispose(true);
             GC.SuppressFinalize(this);
         }

         /// <summary>
         /// 清理所有正在使用的资源。
         /// </summary>
         /// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param>
         protected virtual void Dispose(bool disposing)
         {
             if (disposed)
             {
                 return;
             }
             if (disposing)
             {
                 // Excel Application Quit
                 app.Quit();

                 // Finally, Release app.
                 System.Runtime.InteropServices.Marshal.FinalReleaseComObject(app);
                 app = null;

                 disposed = true;
             }
         }

         #region Worksheet Operation
         /// <summary>
         /// 從工作表讀取數據到 DataTable
         /// </summary>
         /// <param name="fileName">文件</param>
         /// <param name="sheet">工作表名</param>
         /// <returns>DataTable</returns>
         public DataTable GetDataTableFromSheet(string fileName, string sheet, int rows, int cols)
         {
             // Create Table
             DataTable dt = new DataTable();

             // Get Excel's WorkBooks. Attention: Don't use .Net cascade, ex.: app.Workbooks.Add()
             // Every variable Must set to reference, then Release it one by one.
             // If not, Can't quit Excel Process.
             wbs = app.Workbooks;

             // Get WorkBook
             wb = wbs.Open(fileName);

             // Get WorkSheet
             ws = wb.Sheets[sheet];

             // Columns & Rows Count
             //int colCount = ws.UsedRange.CurrentRegion.Columns.Count;
             //int rowCount = ws.UsedRange.CurrentRegion.Rows.Count;

             // Get worksheet's used range
             //rng = ws.UsedRange;
             rng = ws.Range[ws.Range["A1"], ws.Range[GetColumnName(cols)+rows]];
             dt = GetDataTableFromRange(rng, rows, cols);

             // Relase Range, Set to null. (variable reference that COM Object's Count is 0)
             System.Runtime.InteropServices.Marshal.FinalReleaseComObject(rng);
             rng = null;

             // Release WorkSheet
             System.Runtime.InteropServices.Marshal.FinalReleaseComObject(ws);
             ws = null;

             // Release WorkBook
             System.Runtime.InteropServices.Marshal.FinalReleaseComObject(wb);
             wb = null;

             // Release WorkBooks
             System.Runtime.InteropServices.Marshal.FinalReleaseComObject(wbs);
             wbs = null;

             return dt;
         }
         #endregion

         #region Range Operation
         /// <summary>
         /// 從單元格範圍讀取數據到 DataTable
         /// </summary>
         /// <param name="range">單元格範圍</param>
         /// <returns>DataTable</returns>
         private DataTable GetDataTableFromRange(Range range, int rows, int cols)
         {
             DataTable dataTable = new DataTable();

             // First Row Range
             Range titleRange = range.Rows[];

             // Columns Count
             //int colCount = titleRange.CurrentRegion.Columns.Count;

             // Title Row has Empty Cell Or Replication, Use Excel Column Header.
             if (titleRange.Cells.Cast<Range>().Any(s => s.Value2 == null)
                 || titleRange.Cells.Cast<Range>().GroupBy(s => s.Value2).Count() != titleRange.Cells.Count
                 || titleRange.CurrentRegion.Columns.Count != cols)
             {
                 for (int i = ; i <= cols; i++)
                 {
                     dataTable.Columns.Add(GetColumnName(i), typeof(string));
                 }
             }
             else
                 dataTable = GetTableStructureFromTitleRange(range);

             // Release Range Object
             System.Runtime.InteropServices.Marshal.FinalReleaseComObject(titleRange);
             titleRange = null;

             // Insert Data To DataTable Wtih Range Value
             object[,] arr = range.Value;
             for (int i = ; i < arr.GetLength(); i++)
             {
                 DataRow dr = dataTable.NewRow();
                 for (int j = ; j < arr.GetLength(); j++)
                 {
                     if (arr[i + , j + ] != null)
                         dr[j] = arr[i + , j + ];
                     else
                         dr[j] = "";
                 }

                 dataTable.Rows.Add(dr);
             }

             return dataTable;
         }

         /// <summary>
         /// 生成表頭。如果首行表頭規範，則採用首行表頭，否則用Excel表頭代替
         /// </summary>
         /// <param name="titleRow">首行範圍</param>
         /// <param name="isAllString">全部採用字符串格式</param>
         /// <returns>DataTable</returns>
         private DataTable GetTableStructureFromTitleRange(Range titleRow, bool isAllString = true)
         {
             DataTable dataTable = new System.Data.DataTable();
             foreach (Range cell in titleRow.Cells)
             {
                 if (isAllString)
                     dataTable.Columns.Add(cell.Value2, typeof(string));
                 else
                     dataTable.Columns.Add(cell.Value2, typeof(object));
             }
             return dataTable;
         }
         #endregion

         #region Column Operation
         /// <summary>
         /// 使用 Excel 標頭的方式生成字母列頭
         /// </summary>
         /// <param name="index">索引號</param>
         /// <returns>字母列頭</returns>
         public string GetColumnName(int index)
         {
             var dividend = index;
             var columnName = string.Empty;

             while (dividend > )
             {
                 var modulo = (dividend - ) % ;
                 columnName = Convert.ToChar( + modulo) + columnName;
                 dividend = (dividend - modulo) / ;
             }

             return columnName;
         }
         #endregion
     }