NPOI excel操作

using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using System.Text;

public class ExcelHelper
{
    /// <summary>
    /// 将json转换为DataTable
    /// </summary>
    /// <param name="strJson">得到的json</param>
    /// <returns></returns>
    public static DataTable JsonToDataTable(string strJson)
    {
        //转换json格式
        strJson = strJson.Replace(","", "*"").Replace("":", ""#").ToString();
        //取出表名
        var rg = new System.Text.RegularExpressions.Regex(@"(?<={)[^:]+(?=:[)", System.Text.RegularExpressions.RegexOptions.IgnoreCase);
        string strName = rg.Match(strJson).Value;
        DataTable tb = null;
        //去除表名
        strJson = strJson.Substring(strJson.IndexOf("[") + 1);
        strJson = strJson.Substring(0, strJson.IndexOf("]"));
        //获取数据
        rg = new System.Text.RegularExpressions.Regex(@"(?<={)[^}]+(?=})");
        System.Text.RegularExpressions.MatchCollection mc = rg.Matches(strJson);
        for (int i = 0; i < mc.Count; i++)
        {
            string strRow = mc[i].Value;
            string[] strRows = strRow.Split('*');
            //创建表
            if (tb == null)
            {
                tb = new DataTable();
                tb.TableName = strName;
                foreach (string str in strRows)
                {
                    var dc = new DataColumn();
                    string[] strCell = str.Split('#');
                    if (strCell[0].Substring(0, 1) == """)
                    {
                        int a = strCell[0].Length;
                        dc.ColumnName = strCell[0].Substring(1, a - 2);
                    }
                    else
                    {
                        dc.ColumnName = strCell[0];
                    }
                    tb.Columns.Add(dc);
                }
                tb.AcceptChanges();
            }
            //增加内容
            DataRow dr = tb.NewRow();
            for (int r = 0; r < strRows.Length; r++)
            {
                try
                {
                    string a = strRows[r].Split('#')[1].Trim();
                    if (a.Equals("null"))
                    {
                        dr[r] = "";
                    }
                    else
                    {
                        dr[r] = strRows[r].Split('#')[1].Trim().Replace("，", ",").Replace("：", ":").Replace(""", "");
                    }
                }
                catch (Exception e)
                {
                    throw e;
                }
            }
            tb.Rows.Add(dr);
            tb.AcceptChanges();
        }
        try
        {
            if (tb != null)
            {
                return tb;
            }
            else
            {
                throw new Exception("解析错误");
            }
        }
        catch (Exception e)
        {
            throw e;
        }
    }
    //Datatable导出Excel
    public static void GridToExcelByNPOI(DataTable dt, string strExcelFileName)
    {
        try
        {
            HSSFWorkbook workbook = new HSSFWorkbook();
            ISheet sheet = workbook.CreateSheet("Sheet1");
            ICellStyle HeadercellStyle = workbook.CreateCellStyle();
            HeadercellStyle.BorderBottom = NPOI.SS.UserModel.BorderStyle.Thin;
            HeadercellStyle.BorderLeft = NPOI.SS.UserModel.BorderStyle.Thin;
            HeadercellStyle.BorderRight = NPOI.SS.UserModel.BorderStyle.Thin;
            HeadercellStyle.BorderTop = NPOI.SS.UserModel.BorderStyle.Thin;
            HeadercellStyle.Alignment = NPOI.SS.UserModel.HorizontalAlignment.Center;
            //字体
            NPOI.SS.UserModel.IFont headerfont = workbook.CreateFont();
            headerfont.Boldweight = (short)FontBoldWeight.Bold;
            HeadercellStyle.SetFont(headerfont);
            //用column name 作为列名
            int icolIndex = 0;
            IRow headerRow = sheet.CreateRow(0);
            foreach (DataColumn item in dt.Columns)
            {
                ICell cell = headerRow.CreateCell(icolIndex);
                cell.SetCellValue(item.ColumnName);
                cell.CellStyle = HeadercellStyle;
                icolIndex++;
            }
            ICellStyle cellStyle = workbook.CreateCellStyle();
            //为避免日期格式被Excel自动替换，所以设定 format 为 『@』 表示一率当成text來看
            cellStyle.DataFormat = HSSFDataFormat.GetBuiltinFormat("@");
            cellStyle.BorderBottom = NPOI.SS.UserModel.BorderStyle.Thin;
            cellStyle.BorderLeft = NPOI.SS.UserModel.BorderStyle.Thin;
            cellStyle.BorderRight = NPOI.SS.UserModel.BorderStyle.Thin;
            cellStyle.BorderTop = NPOI.SS.UserModel.BorderStyle.Thin;
            NPOI.SS.UserModel.IFont cellfont = workbook.CreateFont();
            cellfont.Boldweight = (short)FontBoldWeight.Normal;
            cellStyle.SetFont(cellfont);
            //建立内容行
            int iRowIndex = 1;
            int iCellIndex = 0;
            foreach (DataRow Rowitem in dt.Rows)
            {
                IRow DataRow = sheet.CreateRow(iRowIndex);
                foreach (DataColumn Colitem in dt.Columns)
                {
                    ICell cell = DataRow.CreateCell(iCellIndex);
                    cell.SetCellValue(Rowitem[Colitem].ToString());
                    cell.CellStyle = cellStyle;
                    iCellIndex++;
                }
                iCellIndex = 0;
                iRowIndex++;
            }
            //自适应列宽度
            for (int i = 0; i < icolIndex; i++)
            {
                sheet.AutoSizeColumn(i);
            }
            //写Excel
            FileStream file = new FileStream(strExcelFileName, FileMode.OpenOrCreate);
            workbook.Write(file);
            file.Flush();
            file.Close();
            // MessageBox.Show(m_Common_ResourceManager.GetString("Export_to_excel_successfully"), m_Common_ResourceManager.GetString("Information"), MessageBoxButtons.OK, MessageBoxIcon.Information);
        }
        catch (Exception ex)
        {
            //ILog log = LogManager.GetLogger("Exception Log");
            //  log.Error(ex.Message + Environment.NewLine + ex.StackTrace);
            //记录AuditTrail
            // CCFS.Framework.BLL.AuditTrailBLL.LogAuditTrail(ex);
            // MessageBox.Show(m_Common_ResourceManager.GetString("Export_to_excel_failed"), m_Common_ResourceManager.GetString("Information"), MessageBoxButtons.OK, MessageBoxIcon.Information);
        }
        // finally { workbook = null; }
    }
}