使用NPOI时写的几个辅助方法

简介：包含：获取单元格合并信息GetMergedCellAddress、获取引用单元格字符串ConvertAddressToString、获取单元格字符串格式内容CellValueToString  

public class ExcelHelper
    {
        /// <summary>
        /// Return cell's CellRangeAddress if that is a merged cell, otherwise return null
        /// </summary>
        /// <param name="cell">the cell will be checked</param>
        /// <returns>the cell's CellRangeAddress</returns>
        public static CellRangeAddress GetMergedCellAddress(ICell cell)
        {
            //not merged cell
            if (cell.IsMergedCell == false)
                return null;

            int MergedRegionsNum = cell.Sheet.NumMergedRegions;
            for(int index = 0; index < MergedRegionsNum; index++)
            {
                CellRangeAddress address = cell.Sheet.GetMergedRegion(index);
                if (address.FirstRow == cell.RowIndex && address.FirstColumn == cell.ColumnIndex)
                    return address;
            }

            //no match
            return null;
        }

        /// <summary>
        /// 将Excel行列索引号（从0开始）转换为引用地址，分非R1C1格式（默认）和R1C1格式
        /// </summary>
        /// <param name="rowIndex">行索引号（从0开始）</param>
        /// <param name="columnIndex">列索引号（从0开始）</param>
        /// <param name="isR1C1Format">是否R1C1格式（默认为否）</param>
        /// <returns>Excel单元格引用地址字符串</returns>
        public static string ConvertAddressToString(int rowIndex, int columnIndex, bool isR1C1Format = false)
        {
            if (rowIndex < 0 || columnIndex < 0)
                throw new IndexOutOfRangeException("行/列索引号不可为负数");
            if (isR1C1Format)
                //R1C1格式行号在前列号在后 eg:R2C3 第2行第3列
                return string.Format("R{0}C{1}", rowIndex + 1, columnIndex + 1);
            else
            {
                //非R1C1格式列号在前行号在后 eg:C5 第5行第3列
                //convert column num to letter
                int num = columnIndex;
                string colAddress = string.Empty;
                while(num > -1)
                {
                    int remainder = num >= 26 ? num % 26 : num;
                    colAddress = (char)(remainder + 65) + colAddress;
                    num = (num / 26) - 1;
                }

                return string.Format("{1}{0}", rowIndex + 1, colAddress);
            }
        }

        /// <summary>
        /// 获取Excel单元格引用地址，分非R1C1格式（默认）和R1C1格式
        /// </summary>
        /// <param name="cell">引用单元格</param>
        /// <param name="isR1C1Format">是否R1C1格式（默认为否）</param>
        /// <returns>Excel单元格引用地址字符串</returns>
        public static string ConvertAddressToString(ICell cell, bool isR1C1Format = false)
        {
            return ConvertAddressToString(cell.RowIndex, cell.ColumnIndex, isR1C1Format);
        }

        /// <summary>
        /// 获取Excel单元格值（字符串格式）
        /// </summary>
        /// <param name="cell">单元格</param>
        /// <returns>单元格字符串格式值内容</returns>
        public static string CellValueToString(ICell cell)
        {
            if (cell == null)
                return null;
            switch (cell.CellType)
            {
                case CellType.Blank:
                    return string.Empty;
                case CellType.String:
                    return cell.StringCellValue;
                case CellType.Boolean:
                    return cell.BooleanCellValue.ToString();
                case CellType.Error:
                    return cell.ErrorCellValue.ToString();
                case CellType.Formula:
                    return cell.CellFormula;
                case CellType.Numeric:
                case CellType.Unknown:
                default:
                    return cell.ToString();
            }
        }
    }