NPOIExcelHelper

using System.Data;
using System.Configuration;
using System.Web;
using System.IO;
using System.Text;
using NPOI;
using NPOI.HPSF;
using NPOI.HSSF;
using NPOI.HSSF.UserModel;
using NPOI.HSSF.Util;
using NPOI.POIFS;
using NPOI.Util;


public class NPOIExcelHelper
{
    /// <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 DataTableToExcel(DataTable dtSource, string strHeaderText, string strFileName)
    {
        using (MemoryStream ms = DataTableToExcel(dtSource, strHeaderText))
        {
            using (FileStream fs = new FileStream(strFileName, FileMode.Create, FileAccess.Write))
            {
                byte[] data = ms.ToArray();
                fs.Write(data, 0, 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 DataTableToExcel(DataTable dtSource, string strHeaderText)
    {
        HSSFWorkbook workbook = new HSSFWorkbook();
        HSSFSheet sheet = (HSSFSheet)workbook.CreateSheet();

        #region 右击文件 属性信息
        {
            DocumentSummaryInformation dsi = PropertySetFactory.CreateDocumentSummaryInformation();
            dsi.Company = "NPOI";
            workbook.DocumentSummaryInformation = dsi;

            SummaryInformation si = PropertySetFactory.CreateSummaryInformation();
            si.Author = "文件作者信息"; //填加xls文件作者信息
            si.ApplicationName = "创建程序信息"; //填加xls文件创建程序信息
            si.LastAuthor = "最后保存者信息"; //填加xls文件最后保存者信息
            si.Comments = "作者信息"; //填加xls文件作者信息
            si.Title = "标题信息"; //填加xls文件标题信息
            si.Subject = "主题信息";//填加文件主题信息
            si.CreateDateTime = System.DateTime.Now;
            workbook.SummaryInformation = si;
        }
        #endregion

        HSSFCellStyle dateStyle = (HSSFCellStyle)workbook.CreateCellStyle();
        HSSFDataFormat format = (HSSFDataFormat)workbook.CreateDataFormat();
        dateStyle.DataFormat = format.GetFormat("yyyy-MM-dd HH:mm:ss");
        

        //取得列宽
        int[] arrColWidth = new int[dtSource.Columns.Count];
        foreach (DataColumn item in dtSource.Columns)
        {
            arrColWidth[item.Ordinal] = Encoding.GetEncoding(936).GetBytes(item.ColumnName.ToString()).Length;
        }
        for (int i = 0; i < dtSource.Rows.Count; i++)
        {
            for (int j = 0; j < dtSource.Columns.Count; j++)
            {
                int intTemp = Encoding.GetEncoding(936).GetBytes(dtSource.Rows[i][j].ToString()).Length;
                if (intTemp > arrColWidth[j])
                {
                    arrColWidth[j] = intTemp;
                }
            }
        }
        int rowIndex = 0;
        foreach (DataRow row in dtSource.Rows)
        {
            #region 新建表，填充表头，填充列头，样式
            if (rowIndex == 65535 || rowIndex == 0)
            {
                if (rowIndex != 0)
                {
                    sheet = (HSSFSheet)workbook.CreateSheet();
                }

                #region 表头及样式
                {
                    HSSFRow headerRow = (HSSFRow)sheet.CreateRow(0);
                    headerRow.HeightInPoints = 25;
                    headerRow.CreateCell(0).SetCellValue(strHeaderText);

                    HSSFCellStyle headStyle = (HSSFCellStyle)workbook.CreateCellStyle();
                    //  headStyle.Alignment = CellHorizontalAlignment.CENTER;
                    HSSFFont font = (HSSFFont)workbook.CreateFont();
                    font.FontHeightInPoints = 20;
                    font.Boldweight = 700;
                    headStyle.SetFont(font);
                    headerRow.GetCell(0).CellStyle = headStyle;
                    // sheet.AddMergedRegion(new Region(0, 0, 0, dtSource.Columns.Count - 1));
                    //headerRow.Dispose();
                }
                #endregion


                #region 列头及样式
                {
                    HSSFRow headerRow = (HSSFRow)sheet.CreateRow(1);
                    HSSFCellStyle headStyle = (HSSFCellStyle)workbook.CreateCellStyle();
                    //headStyle.Alignment = CellHorizontalAlignment.CENTER;
                    HSSFFont font = (HSSFFont)workbook.CreateFont();
                    font.FontHeightInPoints = 10;
                    font.Boldweight = 700;
                    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] + 1) * 300);
                    }
                    // headerRow.Dispose();
                }
                #endregion

                rowIndex = 2;
            }
            #endregion


            #region 填充内容
            HSSFRow dataRow = (HSSFRow)sheet.CreateRow(rowIndex);
            foreach (DataColumn column in dtSource.Columns)
            {
                HSSFCell newCell = (HSSFCell)dataRow.CreateCell(column.Ordinal);

                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
                        System.DateTime dateV;
                        System.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 = 0;
                        int.TryParse(drValue, out intV);
                        newCell.SetCellValue(intV);
                        break;
                    case "System.Decimal"://浮点型
                    case "System.Double":
                        double doubV = 0;
                        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++;
        }
        MemoryStream ms = new MemoryStream();

        workbook.Write(ms);
        ms.Flush();
        ms.Position = 0;

        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);
        }
        HSSFSheet sheet = (HSSFSheet)hssfworkbook.GetSheetAt(0);
        System.Collections.IEnumerator rows = sheet.GetRowEnumerator();

        HSSFRow headerRow = (HSSFRow)sheet.GetRow(0);
        int cellCount = headerRow.LastCellNum;

        for (int j = 0; j < cellCount; j++)
        {
            HSSFCell cell = (HSSFCell)headerRow.GetCell(j);
            dt.Columns.Add(cell.ToString());
        }

        for (int i = (sheet.FirstRowNum + 1); i <= sheet.LastRowNum; i++)
        {
            HSSFRow row = (HSSFRow)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;
    }
}