在开发中有这样一个需求，邮件预警的时候，要求邮件主体内容是一个Chart 图表（生成后的img），邮件需要有附件，且附件是Excel列表加图表，图表类型是混合图。
回顾：在之前一篇讲到如何使用 EPPlus创建excel 、批量填充、设置套用表格格式、创建chart 图表、设置chart 图表主题。
优点处理简单，生成速度快，批量填充很好用、灵活设置表格样式，自动填充数据和数据格式，对于单一生成excel 表格很友好，唯一不足的地方是chart 图表只能设置单一图表类型，不能设置混合图表，不能把Excel chart 图表读取出来生成img 图片。

回到需求，要实习的功能
一、图表创建、批量填充 、套用表格格式
二、在创建的Excel里面创建 chart 混合图表，设置双Y轴
三、读取 Excel里面的图表，把图表生成img 图片
四、Excel 附件和图片不做本地保存直接通过邮件发送出去

代码：

using Spire.Xls;
using Spire.Xls.Charts;
using System;
using System.Collections.Generic;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;
using System.Drawing.Imaging;
using System.Data;
using System.IO;
using System.Net.Mail;
using System.Net;namespace ConsoleApp3
{class Program{static void Main(string[] args){if (false){Main3();return;}//创建一个Workbook类实例，加载Excel文档Workbook workbook = new Workbook();workbook.LoadFromFile(@"C:\Users\XXXXXXXXXXXX\bin\Debug\Line.xlsx");//获取第一个工作表Worksheet sheet = workbook.Worksheets[0];//设置工作表的名称sheet.Name = "柱状图";sheet.GridLinesVisible = false;//创建柱状图Chart chart = sheet.Charts.Add(ExcelChartType.ColumnClustered);//指定用于生成图表的数据区域chart.DataRange = sheet.Range["A2:E4"];chart.SeriesDataFromRange = false;//指定图表所在的位置chart.LeftColumn = 1;chart.TopRow = 9;chart.RightColumn = 12;chart.BottomRow = 26;//设置图表的名称及字体格式chart.ChartTitle = "上半年产品销售情况(单位：万美元)";chart.ChartTitleArea.IsBold = true;chart.ChartTitleArea.Size = 12;//设置X轴坐标名称及字体格式chart.PrimaryCategoryAxis.Title = "产品类别";chart.PrimaryCategoryAxis.Font.IsBold = true;chart.PrimaryCategoryAxis.TitleArea.IsBold = false;//设置Y轴坐标名称及字体格式chart.PrimaryValueAxis.Title = "销售额";chart.PrimaryValueAxis.HasMajorGridLines = false;chart.PrimaryValueAxis.TitleArea.TextRotationAngle = 90;chart.PrimaryValueAxis.MinValue = 0.5;chart.PrimaryValueAxis.TitleArea.IsBold = false;//设置图例的位置chart.Legend.Position = LegendPositionType.Right;//保存文档workbook.SaveToFile("ColumnChart.xlsx", ExcelVersion.Version2013);//加载生成图表后的Excel文档workbook.LoadFromFile("ColumnChart.xlsx");//遍历工作簿，诊断是否包含图表Image[] images = workbook.SaveChartAsImage(sheet);for (int i = 0; i < images.Length; i++){//将图表保存为图片images[i].Save(string.Format("img-{0}.png", i), ImageFormat.Png);}}public static void Main2(){// 创建Workbook对象Workbook workbook = new Workbook();// 获取第一个工作表Worksheet sheet = workbook.Worksheets[0];// 创建一个DataTable并填充数据DataTable table = new DataTable();table.Columns.Add("Category", typeof(string));table.Columns.Add("Value1", typeof(int));table.Columns.Add("Value2", typeof(int));table.Columns.Add("Value3", typeof(int));table.Columns.Add("Value4", typeof(int));table.Rows.Add("A", 7, 950, 680, 980);table.Rows.Add("B", 8, 500, 720, 1070);table.Rows.Add("C", 9, 900, 890, 1200);//Category	Value1	Value2	Value3	Value4// 将DataTable中的数据批量填充到Excel表格中sheet.InsertDataTable(table, true, 1, 1); 设置数据//sheet.Range["A1"].Text = "Category";//sheet.Range["A2"].Text = "A";//sheet.Range["A3"].Text = "B";//sheet.Range["A4"].Text = "C";//sheet.Range["B1"].Text = "Value1";//sheet.Range["B2"].NumberValue = 7;//sheet.Range["B3"].NumberValue = 8;//sheet.Range["B4"].NumberValue = 9;//sheet.Range["C1"].Text = "Value2";//sheet.Range["C2"].NumberValue = 950;//sheet.Range["C3"].NumberValue = 500;//sheet.Range["C4"].NumberValue = 900;//sheet.Range["D1"].Text = "Value3";//sheet.Range["D2"].NumberValue = 680;//sheet.Range["D3"].NumberValue = 720;//sheet.Range["D4"].NumberValue = 890;//sheet.Range["E1"].Text = "Value4";//sheet.Range["E2"].NumberValue = 980;//sheet.Range["E3"].NumberValue = 1070;//sheet.Range["E4"].NumberValue = 1200;// 添加柱状图Chart chart = sheet.Charts.Add(ExcelChartType.ColumnClustered);chart.DataRange = sheet.Range["B1:E4"];chart.SeriesDataFromRange = false;chart.TopRow = 7;chart.BottomRow = 28;chart.LeftColumn = 3;chart.RightColumn = 11;var cs1 = (ChartSerie)chart.Series[0];cs1.SerieType = ExcelChartType.ColumnClustered;var cs2 = (ChartSerie)chart.Series[1];cs2.SerieType = ExcelChartType.ColumnClustered;var cs3 = (ChartSerie)chart.Series[2];cs3.SerieType = ExcelChartType.Line;chart.SecondaryCategoryAxis.IsMaxCross = true;cs3.UsePrimaryAxis = false;// 保存Excel文件workbook.SaveToFile("Line.xlsx", ExcelVersion.Version2010);}public static void Main3(){Workbook workbook = new Workbook();Worksheet sheet = workbook.Worksheets[0];DataTable table = new DataTable();table.Columns.Add("Category", typeof(string));table.Columns.Add("Value1", typeof(int));table.Columns.Add("Value2", typeof(int));table.Columns.Add("Value3", typeof(int));table.Columns.Add("Value4", typeof(int));table.Rows.Add("A", 7, 950, 680, 980);table.Rows.Add("B", 8, 500, 720, 1070);table.Rows.Add("C", 9, 900, 890, 1200);// Category	Value1	Value2	Value3	Value4// 将DataTable中的数据批量填充到Excel表格中sheet.InsertDataTable(table, true, 1, 1);// 添加柱状图Chart chart = sheet.Charts.Add(ExcelChartType.ColumnClustered);chart.DataRange = sheet.Range["B1:E4"];chart.SeriesDataFromRange = false;chart.TopRow = 7;chart.BottomRow = 28;chart.LeftColumn = 3;chart.RightColumn = 11;var cs1 = (ChartSerie)chart.Series[0];cs1.SerieType = ExcelChartType.ColumnClustered;var cs2 = (ChartSerie)chart.Series[1];cs2.SerieType = ExcelChartType.ColumnClustered;var cs3 = (ChartSerie)chart.Series[2];cs3.SerieType = ExcelChartType.Line;chart.SecondaryCategoryAxis.IsMaxCross = true;cs3.UsePrimaryAxis = false;//保存Excel文件//workbook.SaveToFile("Line.xlsx", ExcelVersion.Version2010);workbook.Version = ExcelVersion.Version2013;//遍历工作簿，诊断是否包含图表Image[] images = workbook.SaveChartAsImage(sheet);/*for (int i = 0; i < images.Length; i++){//将图表保存为图片//images[i].Save(string.Format("img-{0}.png", i), ImageFormat.Png);string desktopPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);string imagePath = Path.Combine(desktopPath, string.Format("img-{0}.png", i));images[i].Save(imagePath, ImageFormat.Png);}*/string[] base64Strings = new string[images.Length];for (int i = 0; i < images.Length; i++){using (MemoryStream ms = new MemoryStream()){images[i].Save(ms, ImageFormat.Png);byte[] imageBytes = ms.ToArray();base64Strings[i] = Convert.ToBase64String(imageBytes);}}// 创建 HTML 内容，将图片嵌入其中string htmlBody = "<html><body>";htmlBody += "<p>邮件正文</p>";htmlBody += string.Format("<img src='data:image/png;base64,{0}' />", base64Strings[0]);htmlBody += "</body></html>";// 发送邮件并包含 HTML 内容MailMessage mail = new MailMessage();mail.From = new MailAddress("qy.dan@.com.hk");mail.To.Add("qy.dan.com.hk");mail.Subject = "包含图片的邮件";mail.IsBodyHtml = true;mail.Body = htmlBody;SmtpClient smtp = new SmtpClient("XXX.XXX.105.69");smtp.DeliveryMethod = SmtpDeliveryMethod.Network;smtp.EnableSsl = false;smtp.Host = "XXX.XXX.105.69";smtp.Port = XXX;smtp.UseDefaultCredentials = true;smtp.Send(mail);}}
}

效果:

插件：
Spire.XLS 下载
Spire.XLS 文档
Spire.XLS
https://www.cnblogs.com/landeanfen/p/5888973.html
csdn：
Spire.XLS 系列教程1
Spire.XLS 系列教程2
Spire.XLS 系列教程3
Spire.XLS 系列教程4

扩展参考：
https://www.cnblogs.com/asxinyu/p/4374015.html
https://www.cnblogs.com/asxinyu/p/Bolg_Category_For_TotalAll.html