c# Datatable导出Excel

using npoi.ss.usermodel;
using npoi.xssf.usermodel;
using system;
using system.collections.generic;
using system.data;
using system.io;
using system.linq;
using newtonsoft.json;
namespace easyframe.common
{
    /// <summary>
    ///title调用信息
    /// </summary>
    public class charttitle
    {
        /// <summary>
        /// 调用名
        /// </summary>
        public string callname { get; set; }
        /// <summary>
        /// 标头信息
        /// </summary>
        public list<chartname> setnamelist { get; set; }
    }
    public class chartname
    {
        /// <summary>
        /// 一级标头
        /// </summary>
        public string name { get; set; }
        /// <summary>
        /// 二级标头
        /// </summary>
        public list<string> chartchildnamelist { get; set; }

    }

    public class excelhelper
    {

        //
        /// <summary>
        /// datatable导出excel
        /// </summary>
        /// <param name="dt">数据</param>
        /// <param name="list">表头</param>
        /// <param name="counts">总条数</param>
        /// <param name="filepath">保存地址</param>
        /// <returns></returns>
        public static memorystream writeexcel(datatable dt, list<charttitle> objlist, string filepath)
        {
            var list = objlist.firstordefault(a => a.callname == "ccc").setnamelist;
            if (!string.isnullorempty(filepath) && null != dt && dt.rows.count > 0)
            {
                xssfworkbook book = new xssfworkbook();
                npoi.ss.usermodel.isheet sheet = book.createsheet(dt.tablename);
                icell cell = null;
                icellstyle style = book.createcellstyle();
                ifont font = book.createfont();//创建字体样式  
                ifont fonts = book.createfont();//创建字体样式  
                ifont fontss = book.createfont();//创建字体样式  
                font.color = npoi.hssf.util.hssfcolor.red.index;//设置字体颜色
                icellstyle styles = book.createcellstyle(); //红色
                fonts.color = npoi.hssf.util.hssfcolor.green.index;
                icellstyle styless = book.createcellstyle(); //绿色
                fontss.color = npoi.hssf.util.hssfcolor.blue.index;
                icellstyle stylesss = book.createcellstyle(); //蓝色
                styless.setfont(fonts);
                styles.setfont(font);
                stylesss.setfont(fontss);
                style.alignment = horizontalalignment.center;
                npoi.ss.usermodel.irow row1 = sheet.createrow(0);
                npoi.ss.usermodel.irow row2 = sheet.createrow(1);
                var row = row1;
                int num = 0;//记录列
                var d = true;//是否第一次加载到二级表单
                #region  创建表头
                //两行单列
                for (int i = 0; i < list.count; i++)
                {
                    if (!d)
                    {
                        row = row1;
                        d = true;
                    }
                    if (list[i].chartchildnamelist == null)
                    {
                        cell = row.createcell(num);
                        sheet.setcolumnwidth(num, 15 * 256);
                        cell.setcellvalue(list[i].name);
                        cell.cellstyle = style;
                        sheet.addmergedregion(new npoi.ss.util.cellrangeaddress(0, 1, num, num));
                        num++;
                        continue;
                    }
                    //两行多列
                    var count = list[i].chartchildnamelist.count; //列数
                    cell = row.createcell(num);
                    cell.setcellvalue(list[i].name);
                    cell.cellstyle = style;
                    sheet.addmergedregion(new npoi.ss.util.cellrangeaddress(0, 0, num, count + num - 1));
                    if (d)
                    {
                        d = false;
                        row = row2;
                    }
                    var t = 0;
                    var rang = sheet.getrow(1);
                    for (int j = 0; j < count; j++)
                    {
                        sheet.setcolumnwidth(num + t, 5 * 256);
                        cell = row.createcell(num + t);
                        cell.setcellvalue(list[i].chartchildnamelist[j]);
                        cell.cellstyle = style;
                        t++;
                    }
                    num = num + count;
                }
                #endregion 创建表头
                #region 写入数据
                int customs = 0;//记录列数
                int clouns = 0;//记录行数



                filepath = string.format(filepath, "xxx");
                #region 导出操作
                var data1 = jsonconvert.deserializeobject<list<类名>>(dt.rows[0][0].tostring());
                foreach (var item in data1)
                {
                    npoi.ss.usermodel.irow rows = sheet.createrow(clouns + 2);
                    customs = 0;
                    rows.createcell(customs).setcellvalue(convert.tostring(item.no)); customs++;
                    rows.createcell(customs).setcellvalue(convert.tostring(item.lotteryopenno)); customs++;
                    for (int i = 0; i < item.wan.length; i++)
                    {
                        if (item.lotteryopenno.split(',')[0] == item.wan[i].tostring())
                        {
                            cell = rows.createcell(customs);
                            cell.setcellvalue(item.wan[i]);
                            cell.cellstyle = styles;
                            customs++;
                        }
                        else
                        {
                            rows.createcell(customs).setcellvalue(item.wan[i]); customs++;
                        }
                    }
                    for (int j = 0; j < item.qian.length; j++)
                    {
                        if (item.lotteryopenno.split(',')[1] == item.qian[j].tostring())
                        {
                            cell = rows.createcell(customs);
                            cell.setcellvalue(item.qian[j]);
                            cell.cellstyle = styles;
                            customs++;
                        }
                        else
                        {
                            rows.createcell(customs).setcellvalue(item.qian[j]); customs++;
                        }
                    }
                    for (int k = 0; k < item.bai.length; k++)
                    {
                        if (item.lotteryopenno.split(',')[2] == item.bai[k].tostring())
                        {
                            cell = rows.createcell(customs);
                            cell.setcellvalue(item.bai[k]);
                            cell.cellstyle = styles;
                            customs++;
                        }
                        else
                        {
                            rows.createcell(customs).setcellvalue(item.bai[k]); customs++;
                        }
                    }
                    for (int l = 0; l < item.shi.length; l++)
                    {
                        if (item.lotteryopenno.split(',')[3] == (item.shi[l].tostring()))
                        {
                            cell = rows.createcell(customs);
                            cell.setcellvalue(item.shi[l]);
                            cell.cellstyle = styles;
                            customs++;
                        }
                        else
                        {
                            rows.createcell(customs).setcellvalue(item.shi[l]); customs++;
                        }
                    }
                    for (int m = 0; m < item.ge.length; m++)
                    {
                        if (item.lotteryopenno.split(',')[4] == (item.ge[m].tostring()))
                        {
                            cell = rows.createcell(customs);
                            cell.setcellvalue(item.ge[m]);
                            cell.cellstyle = styles;
                            customs++;
                        }
                        else
                        {
                            rows.createcell(customs).setcellvalue(item.ge[m]); customs++;
                        }
                    }
                    for (int n = 0; n < item.fen.length; n++)
                    {
                        if (item.lotteryopenno.contains(item.fen[n].tostring()))
                        {
                            cell = rows.createcell(customs);
                            cell.setcellvalue(item.fen[n]);
                            cell.cellstyle = styles;
                            customs++;
                        }
                        else
                        {
                            rows.createcell(customs).setcellvalue(item.fen[n]); customs++;
                        }

                    }
                    clouns++;
                }

                #endregion


                #endregion 写入数据
                // 写入到客户端  
                using (system.io.memorystream ms = new system.io.memorystream())
                {
                    book.write(ms);
                    using (filestream fs = new filestream(filepath, filemode.create, fileaccess.write))
                    {
                        byte[] data = ms.toarray();
                        fs.write(data, 0, data.length);
                        fs.flush();
                    }
                    book = null;
                    return ms;
                }
            }
            return null;
        }



    }
}