NPOI 帮助类

NPOI 帮助类

代码实现了来自于互联网

 using System;
 using System.Data;
 using System.IO;
 using System.Text;
 using NPOI.HSSF.UserModel;
 using NPOI.SS.UserModel;
 using NPOI.SS.Util;

 namespace HD.Helper.Common
 {
     /// <summary>
     /// NPOI操作帮助类
     /// </summary>
     public class NPOIHelper
     {
         /// <summary>
         /// DataTable导出到Excel文件
         /// </summary>
         /// <param name="dtSource">源DataTable</param>
         /// <param name="strHeaderText">表头文本</param>
         /// <param name="strFileName">保存位置</param>
         public static void Export(DataTable dtSource, string strHeaderText, string strFileName)
         {
             using (MemoryStream ms = Export(dtSource, strHeaderText))
             {
                 using (FileStream fs = new FileStream(strFileName, FileMode.Create, FileAccess.Write))
                 {
                     byte[] data = ms.ToArray();
                     fs.Write(data, , data.Length);
                     fs.Flush();
                 }
             }
         }

         /// <summary>
         /// DataTable导出到Excel的MemoryStream
         /// </summary>
         /// <param name="dtSource">源DataTable</param>
         /// <param name="strHeaderText">表头文本</param>
         public static MemoryStream Export(DataTable dtSource, string strHeaderText)
         {
             HSSFWorkbook workbook = new HSSFWorkbook();
             ISheet sheet = workbook.CreateSheet();

             ICellStyle dateStyle = workbook.CreateCellStyle();
             IDataFormat format = workbook.CreateDataFormat();
             dateStyle.DataFormat = format.GetFormat("yyyy-MM-dd");

             #region 取得每列的列宽（最大宽度）
             int[] arrColWidth = new int[dtSource.Columns.Count];
             foreach (DataColumn item in dtSource.Columns)
             {
                 //GBK对应的code page是CP936
                 arrColWidth[item.Ordinal] = Encoding.GetEncoding().GetBytes(item.ColumnName.ToString()).Length;
             }
             for (int i = ; i < dtSource.Rows.Count; i++)
             {
                 for (int j = ; j < dtSource.Columns.Count; j++)
                 {
                     int intTemp = Encoding.GetEncoding().GetBytes(dtSource.Rows[i][j].ToString()).Length;
                     if (intTemp > arrColWidth[j])
                     {
                         arrColWidth[j] = intTemp;
                     }
                 }
             }
             #endregion

             int rowIndex = ;

             foreach (DataRow row in dtSource.Rows)
             {
                 #region 新建表，填充表头，填充列头，样式
                 if (rowIndex ==  || rowIndex == )
                 {
                     if (rowIndex != )
                     {
                         sheet = workbook.CreateSheet();
                     }

                     #region 表头及样式
                     {
                         IRow headerRow = sheet.CreateRow();
                         headerRow.HeightInPoints = ;
                         headerRow.CreateCell().SetCellValue(strHeaderText);

                         ICellStyle headStyle = workbook.CreateCellStyle();
                         headStyle.Alignment = HorizontalAlignment.CENTER;
                         IFont font = workbook.CreateFont();
                         font.FontHeightInPoints = ;
                         font.Boldweight = ;
                         headStyle.SetFont(font);

                         headerRow.GetCell().CellStyle = headStyle;

                         sheet.AddMergedRegion(new CellRangeAddress(, , , dtSource.Columns.Count - ));
                     }
                     #endregion

                     #region 列头及样式
                     {
                         IRow headerRow = sheet.CreateRow();
                         ICellStyle headStyle = workbook.CreateCellStyle();
                         headStyle.Alignment = HorizontalAlignment.CENTER;
                         IFont font = workbook.CreateFont();
                         font.FontHeightInPoints = ;
                         font.Boldweight = ;
                         headStyle.SetFont(font);

                         foreach (DataColumn column in dtSource.Columns)
                         {
                             headerRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);
                             headerRow.GetCell(column.Ordinal).CellStyle = headStyle;

                             //设置列宽
                             sheet.SetColumnWidth(column.Ordinal, (arrColWidth[column.Ordinal] + ) * );

                         }
                     }
                     #endregion

                     rowIndex = ;
                 }
                 #endregion

                 #region 填充内容
                 ICellStyle contentStyle = workbook.CreateCellStyle();
                 contentStyle.Alignment = HorizontalAlignment.LEFT;
                 IRow dataRow = sheet.CreateRow(rowIndex);
                 foreach (DataColumn column in dtSource.Columns)
                 {
                     ICell newCell = dataRow.CreateCell(column.Ordinal);
                     newCell.CellStyle = contentStyle;

                     string drValue = row[column].ToString();

                     switch (column.DataType.ToString())
                     {
                         case "System.String"://字符串类型
                             newCell.SetCellValue(drValue);
                             break;
                         case "System.DateTime"://日期类型
                             DateTime dateV;
                             DateTime.TryParse(drValue, out dateV);
                             newCell.SetCellValue(dateV);

                             newCell.CellStyle = dateStyle;//格式化显示
                             break;
                         case "System.Boolean"://布尔型
                             bool boolV = false;
                             bool.TryParse(drValue, out boolV);
                             newCell.SetCellValue(boolV);
                             break;
                         case "System.Int16"://整型
                         case "System.Int32":
                         case "System.Int64":
                         case "System.Byte":
                             int intV = ;
                             int.TryParse(drValue, out intV);
                             newCell.SetCellValue(intV);
                             break;
                         case "System.Decimal"://浮点型
                         case "System.Double":
                             double doubV = ;
                             double.TryParse(drValue, out doubV);
                             newCell.SetCellValue(doubV);
                             break;
                         case "System.DBNull"://空值处理
                             newCell.SetCellValue("");
                             break;
                         default:
                             newCell.SetCellValue("");
                             break;
                     }

                 }
                 #endregion

                 rowIndex++;
             }

             using (MemoryStream ms = new MemoryStream())
             {
                 workbook.Write(ms);
                 ms.Flush();
                 ms.Position = ;

                 //sheet.Dispose();
                 //workbook.Dispose();//一般只用写这一个就OK了，他会遍历并释放所有资源，但当前版本有问题所以只释放sheet
                 return ms;
             }

         }

         /// <summary>读取excel
         /// 默认第一行为标头
         /// </summary>
         /// <param name="strFileName">excel文档路径</param>
         /// <returns></returns>
         public static DataTable Import(string strFileName)
         {
             DataTable dt = new DataTable();

             HSSFWorkbook hssfworkbook;
             using (FileStream file = new FileStream(strFileName, FileMode.Open, FileAccess.Read))
             {
                 hssfworkbook = new HSSFWorkbook(file);
             }
             ISheet sheet = hssfworkbook.GetSheetAt();
             System.Collections.IEnumerator rows = sheet.GetRowEnumerator();

             IRow headerRow = sheet.GetRow();
             int cellCount = headerRow.LastCellNum;

             for (int j = ; j < cellCount; j++)
             {
                 ICell cell = headerRow.GetCell(j);
                 dt.Columns.Add(cell.ToString());
             }

             for (int i = (sheet.FirstRowNum + ); i <= sheet.LastRowNum; i++)
             {
                 IRow row = sheet.GetRow(i);
                 DataRow dataRow = dt.NewRow();

                 for (int j = row.FirstCellNum; j < cellCount; j++)
                 {
                     if (row.GetCell(j) != null)
                         dataRow[j] = row.GetCell(j).ToString();
                 }

                 dt.Rows.Add(dataRow);
             }
             return dt;
         }

     }
 }

额外的示例：https://files.cnblogs.com/files/Music/NPOI_Demo_2018_09_06.rar

额外的示例2：NPOIDemo.rar

谢谢浏览！