npoi workbook 的 cellstyle 创建不能超过4000的解决方法

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利用NPOI进行Excel的工作表(Sheet)复制时,如果复制的工作表(Sheet)较多(100个左右),会报告 workbook 的 cellstyle 创建不能超过4000 的错误.

代码如下:

public static void CopySheet(ISheet fromSheet, ISheet toSheet, bool copyValueFlag)
        {
            //合并区域处理  
            MergerRegion(fromSheet, toSheet);
            System.Collections.IEnumerator rows = fromSheet.GetRowEnumerator();
            while (rows.MoveNext())
            {

                IRow row = null;
                if (fromSheet.Workbook is HSSFWorkbook)
                    row = rows.Current as HSSFRow;
                else
                    row = rows.Current as HSSFRow;
                IRow newRow = toSheet.CreateRow(row.RowNum);
                CopyRow(fromSheet.Workbook, toSheet.Workbook, row, newRow, copyValueFlag);
                
            }
        }

public static void CopyRow(IWorkbook fromWb, IWorkbook toWb, IRow fromRow, IRow toRow, bool copyValueFlag)
        {
            System.Collections.IEnumerator cells = fromRow.GetEnumerator(); //.GetRowEnumerator();  
            toRow.Height = fromRow.Height;
 
            while (cells.MoveNext())
            {
                
                ICell cell = null;
                //ICell cell = (wb is HSSFWorkbook) ? cells.Current as HSSFCell : cells.Current as NPOI.XSSF.UserModel.XSSFCell;  
                if (toWb is HSSFWorkbook)
                    cell = cells.Current as HSSFCell;
                else
                    cell = cells.Current as HSSFCell;
                ICell newCell = toRow.CreateCell(cell.ColumnIndex);
                CopyCell(fromWb, toWb, cell, newCell, copyValueFlag);
  
                
            }
        }

public static void CopyCell(IWorkbook fromWb,IWorkbook toWb, ICell srcCell, ICell distCell, bool copyValueFlag)
        {
            ICellStyle newstyle = toWb.CreateCellStyle(); 

            //复制样式
            newstyle.CloneStyleFrom(srcCell.CellStyle);
            //样式  
            distCell.CellStyle = newstyle;
            //评论  
            if (srcCell.CellComment != null)
            {
                distCell.CellComment = srcCell.CellComment;
            }
            // 不同数据类型处理  
            CellType srcCellType = srcCell.CellType;
            distCell.SetCellType(srcCellType);
            if (copyValueFlag)
            {
                if (srcCellType == CellType.Numeric)
                {
                    if (HSSFDateUtil.IsCellDateFormatted(srcCell))
                    {
                        distCell.SetCellValue(srcCell.DateCellValue);
                    }
                    else
                    {
                        distCell.SetCellValue(srcCell.NumericCellValue);
                    }
                }
                else if (srcCellType == CellType.String)
                {
                    distCell.SetCellValue(srcCell.RichStringCellValue);
                }
                else if (srcCellType == CellType.Blank)
                {
                    // nothing21  
                }
                else if (srcCellType == CellType.Boolean)
                {
                    distCell.SetCellValue(srcCell.BooleanCellValue);
                }
                else if (srcCellType == CellType.Error)
                {
                    distCell.SetCellErrorValue(srcCell.ErrorCellValue);
                }
                else if (srcCellType == CellType.Formula)
                {
                    distCell.SetCellFormula(srcCell.CellFormula);
                }
                else
                {
                    // nothing29  
                }
            }
        }

网上有方法说要把CreateCellStyle放在循环外面,这个方法不适用于复制的工作表(Sheet)较多(100个左右)的场景,且不是解决问题的根本方法.

为了最大限度的复用CellStyle,且控制在4000个之内.构造了一个缓存对象.来缓存创建的CellStyle,所有的CellStyle获取,先通过从缓存取,如果不存在再创建.代码如下:

public class CellStyleCache:ArrayList
    {
        public ICellStyle this[ICellStyle fromStyle]
        {
            get
            {
                foreach (object o in this)
                {
                    ICellStyle toStyle = o as ICellStyle;
                    if 
                        (
                            toStyle.Alignment == fromStyle.Alignment
                            //边框和边框颜色  
                            && toStyle.BorderBottom == fromStyle.BorderBottom
                            && toStyle.BorderLeft == fromStyle.BorderLeft
                            && toStyle.BorderRight == fromStyle.BorderRight
                            && toStyle.BorderTop == fromStyle.BorderTop
                            && toStyle.TopBorderColor == fromStyle.TopBorderColor
                            && toStyle.BottomBorderColor == fromStyle.BottomBorderColor
                            && toStyle.RightBorderColor == fromStyle.RightBorderColor
                            && toStyle.LeftBorderColor == fromStyle.LeftBorderColor
                            //背景和前景  
                            && toStyle.FillBackgroundColor == fromStyle.FillBackgroundColor
                            && toStyle.FillForegroundColor == fromStyle.FillForegroundColor
                            //&& toStyle.DataFormat == fromStyle.DataFormat
                            //&& toStyle.FillPattern == fromStyle.FillPattern 
                            && toStyle.IsHidden == fromStyle.IsHidden
                            //&& toStyle.Indention == fromStyle.Indention//首行缩进  
                            //&& toStyle.IsLocked == fromStyle.IsLocked
                            //&& toStyle.Rotation == fromStyle.Rotation//旋转  
                            && toStyle.VerticalAlignment == fromStyle.VerticalAlignment
                            //&& toStyle.WrapText == fromStyle.WrapText
                        )
                    {
                        return toStyle;
                    }

                }
                return null;
            }
            set
            {
                this.Add(fromStyle);
            }
        }
    }

 public static void CopyCell(IWorkbook fromWb,IWorkbook toWb, ICell srcCell, ICell distCell, bool copyValueFlag)
        {
            //ICellStyle newstyle = toWb.CreateCellStyle();  
            ICellStyle newstyle = CreateCellStyle(toWb, srcCell.CellStyle);

            //复制样式
            newstyle.CloneStyleFrom(srcCell.CellStyle);
            //样式  
            distCell.CellStyle = newstyle;
            //评论  
            if (srcCell.CellComment != null)
            {
                distCell.CellComment = srcCell.CellComment;
            }
            // 不同数据类型处理  
            CellType srcCellType = srcCell.CellType;
            distCell.SetCellType(srcCellType);
            if (copyValueFlag)
            {
                if (srcCellType == CellType.Numeric)
                {
                    if (HSSFDateUtil.IsCellDateFormatted(srcCell))
                    {
                        distCell.SetCellValue(srcCell.DateCellValue);
                    }
                    else
                    {
                        distCell.SetCellValue(srcCell.NumericCellValue);
                    }
                }
                else if (srcCellType == CellType.String)
                {
                    distCell.SetCellValue(srcCell.RichStringCellValue);
                }
                else if (srcCellType == CellType.Blank)
                {
                    // nothing21  
                }
                else if (srcCellType == CellType.Boolean)
                {
                    distCell.SetCellValue(srcCell.BooleanCellValue);
                }
                else if (srcCellType == CellType.Error)
                {
                    distCell.SetCellErrorValue(srcCell.ErrorCellValue);
                }
                else if (srcCellType == CellType.Formula)
                {
                    distCell.SetCellFormula(srcCell.CellFormula);
                }
                else
                {
                    // nothing29  
                }
            }
        }

private static CellStyleCache styleCache = new CellStyleCache();
        public static ICellStyle CreateCellStyle(IWorkbook wb,ICellStyle fromStyle)
        {
            ICellStyle newStyle = styleCache[fromStyle];
            if (newStyle == null)
            {
                newStyle = wb.CreateCellStyle();
            }
            return newStyle;
        }

测试通过.

npoi workbook 的 cellstyle 创建不能超过4000的解决方法

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原文地址：http://blog.csdn.net/sharpnessdotnet/article/details/43407465