.NET Core使用NPOI导出复杂，美观的Excel详解

/**
 * Author:追逐时光
 * Description：Npoi之Excel数据导出帮助类（创建Excel表格行列，设置行高，设置字体样式，单元格边框样式，单元格背景颜色和样式，单元格内容对齐方式等常用属性和样式封装）
 * Description：2020年3月29日
 */
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.HSSF.Util;

namespace YY_Utility
{
    public class NpoiExcelExportHelper
    {
        private static NpoiExcelExportHelper _exportHelper;

        public static NpoiExcelExportHelper _
        {
            get => _exportHelper ?? (_exportHelper = new NpoiExcelExportHelper());
            set => _exportHelper = value;
        }

        /// <summary>
        /// TODO:先创建行，然后在创建对应的列
        /// 创建Excel中指定的行
        /// </summary>
        /// <param name="sheet">Excel工作表对象</param>
        /// <param name="rowNum">创建第几行(从0开始)</param>
        /// <param name="rowHeight">行高</param>
        public HSSFRow CreateRow(ISheet sheet, int rowNum, float rowHeight)
        {
            HSSFRow row = (HSSFRow)sheet.CreateRow(rowNum); //创建行
            row.HeightInPoints = rowHeight; //设置列头行高
            return row;
        }

        /// <summary>
        /// 创建行内指定的单元格
        /// </summary>
        /// <param name="row">需要创建单元格的行</param>
        /// <param name="cellStyle">单元格样式</param>
        /// <param name="cellNum">创建第几个单元格(从0开始)</param>
        /// <param name="cellValue">给单元格赋值</param>
        /// <returns></returns>
        public HSSFCell CreateCells(HSSFRow row, HSSFCellStyle cellStyle, int cellNum, string cellValue)
        {
            HSSFCell cell = (HSSFCell)row.CreateCell(cellNum); //创建单元格
            cell.CellStyle = cellStyle; //将样式绑定到单元格
            if (!string.IsNullOrWhiteSpace(cellValue))
            {
                //单元格赋值
                cell.SetCellValue(cellValue);
            }

            return cell;
        }


        /// <summary>
        /// 行内单元格常用样式设置
        /// </summary>
        /// <param name="workbook">Excel文件对象</param>
        /// <param name="hAlignment">水平布局方式</param>
        /// <param name="vAlignment">垂直布局方式</param>
        /// <param name="fontHeightInPoints">字体大小</param>
        /// <param name="isAddBorder">是否需要边框</param>
        /// <param name="boldWeight">字体加粗 (None = 0,Normal = 400，Bold = 700</param>
        /// <param name="fontName">字体（仿宋，楷体，宋体，微软雅黑...与Excel主题字体相对应）</param>
        /// <param name="isAddBorderColor">是否增加边框颜色</param>
        /// <param name="isItalic">是否将文字变为斜体</param>
        /// <param name="isLineFeed">是否自动换行</param>
        /// <param name="isAddCellBackground">是否增加单元格背景颜色</param>
        /// <param name="fillPattern">填充图案样式(FineDots 细点，SolidForeground立体前景，isAddFillPattern=true时存在)</param>
        /// <param name="cellBackgroundColor">单元格背景颜色（当isAddCellBackground=true时存在）</param>
        /// <param name="fontColor">字体颜色</param>
        /// <param name="underlineStyle">下划线样式（无下划线[None],单下划线[Single],双下划线[Double],会计用单下划线[SingleAccounting],会计用双下划线[DoubleAccounting]）</param>
        /// <param name="typeOffset">字体上标下标(普通默认值[None],上标[Sub],下标[Super]),即字体在单元格内的上下偏移量</param>
        /// <param name="isStrikeout">是否显示删除线</param>
        /// <returns></returns>
        public HSSFCellStyle CreateStyle(HSSFWorkbook workbook, HorizontalAlignment hAlignment, VerticalAlignment vAlignment, short fontHeightInPoints, bool isAddBorder, short boldWeight, string fontName = "宋体", bool isAddBorderColor = true, bool isItalic = false, bool isLineFeed = false, bool isAddCellBackground = false, FillPattern fillPattern = FillPattern.NoFill, short cellBackgroundColor = HSSFColor.Yellow.Index, short fontColor = HSSFColor.Black.Index, FontUnderlineType underlineStyle =
            FontUnderlineType.None, FontSuperScript typeOffset = FontSuperScript.None, bool isStrikeout = false)
        {
            HSSFCellStyle cellStyle = (HSSFCellStyle)workbook.CreateCellStyle(); //创建列头单元格实例样式
            cellStyle.Alignment = hAlignment; //水平居中
            cellStyle.VerticalAlignment = vAlignment; //垂直居中
            cellStyle.WrapText = isLineFeed;//自动换行



            //背景颜色，边框颜色，字体颜色都是使用 HSSFColor属性中的对应调色板索引，关于 HSSFColor 颜色索引对照表，详情参考：https://www.cnblogs.com/Brainpan/p/5804167.html

            //TODO：引用了NPOI后可通过ICellStyle 接口的 FillForegroundColor 属性实现 Excel 单元格的背景色设置，FillPattern 为单元格背景色的填充样式

            //TODO:十分注意，要设置单元格背景色必须是FillForegroundColor和FillPattern两个属性同时设置，否则是不会显示背景颜色
            if (isAddCellBackground)
            {
                cellStyle.FillForegroundColor = cellBackgroundColor;//单元格背景颜色
                cellStyle.FillPattern = fillPattern;//填充图案样式(FineDots 细点，SolidForeground立体前景)
            }


            //是否增加边框
            if (isAddBorder)
            {
                //常用的边框样式 None(没有),Thin(细边框，瘦的),Medium(中等),Dashed(虚线),Dotted(星罗棋布的),Thick(厚的),Double(双倍),Hair(头发)[上右下左顺序设置]
                cellStyle.BorderBottom = BorderStyle.Thin;
                cellStyle.BorderRight = BorderStyle.Thin;
                cellStyle.BorderTop = BorderStyle.Thin;
                cellStyle.BorderLeft = BorderStyle.Thin;
            }

            //是否设置边框颜色
            if (isAddBorderColor)
            {
                //边框颜色[上右下左顺序设置]
                cellStyle.TopBorderColor = HSSFColor.DarkGreen.Index;//DarkGreen(黑绿色)
                cellStyle.RightBorderColor = HSSFColor.DarkGreen.Index;
                cellStyle.BottomBorderColor = HSSFColor.DarkGreen.Index;
                cellStyle.LeftBorderColor = HSSFColor.DarkGreen.Index;
            }

            /**
             * 设置相关字体样式
             */
            var cellStyleFont = (HSSFFont)workbook.CreateFont(); //创建字体

            //假如字体大小只需要是粗体的话直接使用下面该属性即可
            //cellStyleFont.IsBold = true;

            cellStyleFont.Boldweight = boldWeight; //字体加粗
            cellStyleFont.FontHeightInPoints = fontHeightInPoints; //字体大小
            cellStyleFont.FontName = fontName;//字体（仿宋，楷体，宋体 ）
            cellStyleFont.Color = fontColor;//设置字体颜色
            cellStyleFont.IsItalic = isItalic;//是否将文字变为斜体
            cellStyleFont.Underline = underlineStyle;//字体下划线
            cellStyleFont.TypeOffset = typeOffset;//字体上标下标
            cellStyleFont.IsStrikeout = isStrikeout;//是否有删除线

            cellStyle.SetFont(cellStyleFont); //将字体绑定到样式
            return cellStyle;
        }
    }
}

using System;
using System.IO;
using Microsoft.AspNetCore.Hosting;
using NPOI.HSSF.UserModel;
using NPOI.HSSF.Util;
using NPOI.SS.UserModel;
using NPOI.SS.Util;
using YY_Utility;

namespace YY_Services
{
    /// <summary>
    /// Excel文档生成并保存操作类
    /// </summary>
    public class NpoiExcelOperationService
    {
        private static IHostingEnvironment _environment;

        public NpoiExcelOperationService(IHostingEnvironment iEnvironment)
        {
            _environment = iEnvironment;
        }

        /// <summary>
        /// Excel数据导出简单示例
        /// </summary>
        /// <param name="resultMsg">导出结果</param>
        /// <param name="excelFilePath">保存excel文件路径</param>
        /// <returns></returns>
        public bool ExcelDataExport(out string resultMsg, out string excelFilePath)
        {
            var result = true;
            excelFilePath = "";
            resultMsg = "successfully";
            //Excel导出名称
            string excelName = "人才培训课程表";
            try
            {
                //首先创建Excel文件对象
                var workbook = new HSSFWorkbook();

                //创建工作表，也就是Excel中的sheet，给工作表赋一个名称(Excel底部名称)
                var sheet = workbook.CreateSheet("人才培训课程表");

                //sheet.DefaultColumnWidth = 20;//默认列宽

                sheet.ForceFormulaRecalculation = true;//TODO:是否开始Excel导出后公式仍然有效（非必须）

                #region table 表格内容设置

                #region 标题样式

                //设置顶部大标题样式
                var cellStyleFont = NpoiExcelExportHelper._.CreateStyle(workbook, HorizontalAlignment.Center, VerticalAlignment.Center, 20, true, 700, "楷体", true, false, false, true, FillPattern.SolidForeground, HSSFColor.Coral.Index, HSSFColor.White.Index,
                    FontUnderlineType.None, FontSuperScript.None, false);

                //第一行表单
                var row = NpoiExcelExportHelper._.CreateRow(sheet, 0, 28);

                var cell = row.CreateCell(0);
                //合并单元格 例： 第1行到第2行 第3列到第4列围成的矩形区域

                //TODO:关于Excel行列单元格合并问题
                /**
                  第一个参数：从第几行开始合并
                  第二个参数：到第几行结束合并
                  第三个参数：从第几列开始合并
                  第四个参数：到第几列结束合并
                **/
                CellRangeAddress region = new CellRangeAddress(0, 0, 0, 5);
                sheet.AddMergedRegion(region);

                cell.SetCellValue("人才培训课程表");//合并单元格后，只需对第一个位置赋值即可（TODO:顶部标题）
                cell.CellStyle = cellStyleFont;

                //二级标题列样式设置
                var headTopStyle = NpoiExcelExportHelper._.CreateStyle(workbook, HorizontalAlignment.Center, VerticalAlignment.Center, 15, true, 700, "楷体", true, false, false, true, FillPattern.SolidForeground, HSSFColor.Grey25Percent.Index, HSSFColor.Black.Index,
                FontUnderlineType.None, FontSuperScript.None, false);

                //表头名称
                var headerName = new[] { "课程类型", "序号", "日期", "课程名称", "内容概要", "讲师简介" };

                row = NpoiExcelExportHelper._.CreateRow(sheet, 1, 24);//第二行
                for (var i = 0; i < headerName.Length; i++)
                {
                    cell = NpoiExcelExportHelper._.CreateCells(row, headTopStyle, i, headerName[i]);

                    //设置单元格宽度
                    if (headerName[i] == "讲师简介" || headerName[i] == "内容概要")
                    {
                        sheet.SetColumnWidth(i, 10000);
                    }
                    else

                    {
                        sheet.SetColumnWidth(i, 5000);
                    }

                }
                #endregion


                #region 单元格内容信息

                //单元格边框样式
                var cellStyle = NpoiExcelExportHelper._.CreateStyle(workbook, HorizontalAlignment.Center, VerticalAlignment.Center, 10, true, 400);

                //左侧列单元格合并 begin
                //TODO:关于Excel行列单元格合并问题（合并单元格后，只需对第一个位置赋值即可）
                /**
                  第一个参数：从第几行开始合并
                  第二个参数：到第几行结束合并
                  第三个参数：从第几列开始合并
                  第四个参数：到第几列结束合并
                **/
                CellRangeAddress leftOne = new CellRangeAddress(2, 7, 0, 0);

                sheet.AddMergedRegion(leftOne);

                CellRangeAddress leftTwo = new CellRangeAddress(8, 11, 0, 0);

                sheet.AddMergedRegion(leftTwo);

                //左侧列单元格合并 end

                var currentDate = DateTime.Now;

                string[] curriculumList = new[] { "艺术学", "设计学", "材料学", "美学", "心理学", "中国近代史", "管理人员的情绪修炼", "高效时间管理", "有效的目标管理", "沟通与协调" };

                int number = 1;

                for (var i = 0; i < 10; i++)
                {
                    row = NpoiExcelExportHelper._.CreateRow(sheet, i + 2, 20); //sheet.CreateRow(i+2);//在上面表头的基础上创建行
                    switch (number)
                    {
                        case 1:
                            cell = NpoiExcelExportHelper._.CreateCells(row, cellStyle, 0, "公共类课程");
                            break;
                        case 7:
                            cell = NpoiExcelExportHelper._.CreateCells(row, cellStyle, 0, "管理类课程");
                            break;
                    }

                    //创建单元格列公众类课程
                    cell = NpoiExcelExportHelper._.CreateCells(row, cellStyle, 1, number.ToString());
                    cell = NpoiExcelExportHelper._.CreateCells(row, cellStyle, 2, currentDate.AddDays(number).ToString("yyyy-MM-dd"));
                    cell = NpoiExcelExportHelper._.CreateCells(row, cellStyle, 3, curriculumList[i]);
                    cell = NpoiExcelExportHelper._.CreateCells(row, cellStyle, 4, "提升，充实，拓展自己综合实力");
                    cell = NpoiExcelExportHelper._.CreateCells(row, cellStyle, 5, "追逐时光_" + number + "号金牌讲师！");

                    number++;
                }
                #endregion

                #endregion

                string folder = DateTime.Now.ToString("yyyyMMdd");


                //保存文件到静态资源文件夹中（wwwroot）,使用绝对路径
                var uploadPath = _environment.WebRootPath + "/UploadFile/" + folder + "/";

                //excel保存文件名
                string excelFileName = excelName + "_" + DateTime.Now.ToString("yyyyMMddHHmmss") + ".xls";

                //创建目录文件夹
                if (!Directory.Exists(uploadPath))
                {
                    Directory.CreateDirectory(uploadPath);
                }

                //Excel的路径及名称
                string excelPath = uploadPath + excelFileName;

                //使用FileStream文件流来写入数据（传入参数为：文件所在路径，对文件的操作方式，对文件内数据的操作）
                var fileStream = new FileStream(excelPath, FileMode.OpenOrCreate, FileAccess.ReadWrite);

                //向Excel文件对象写入文件流，生成Excel文件
                workbook.Write(fileStream);

                //关闭文件流
                fileStream.Close();

                //释放流所占用的资源
                fileStream.Dispose();

                //excel文件保存的相对路径，提供前端下载
                var relativePositioning = "/UploadFile/" + folder + "/" + excelFileName;

                excelFilePath = relativePositioning;
            }
            catch (Exception e)
            {
                result = false;
                resultMsg = e.Message;
            }
            return result;
        }

    }
}