C# EPPlus 导出Excel

一、Excel导出帮助类

    /*引用NuGet包 EPPlus*/
    /// <summary>
    /// Excel导出帮助类
    /// </summary>
    public class ExcelExportHelper
    {
        public static string ExcelContentType => "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
        /// <summary>
        /// List转DataTable
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="data"></param>
        /// <returns></returns>
        public static DataTable ListToDataTable<T>(List<T> data)
        {
            PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(typeof(T));
            DataTable dataTable = new DataTable();
            for (int i = 0; i < properties.Count; i++)
            {
                PropertyDescriptor property = properties[i];
                dataTable.Columns.Add(property.Name, Nullable.GetUnderlyingType(property.PropertyType) ?? property.PropertyType);
            }
            object[] values = new object[properties.Count];
            foreach (T item in data)
            {
                for (int i = 0; i < values.Length; i++)
                {
                    values[i] = properties[i].GetValue(item);
                }
                dataTable.Rows.Add(values);
            }
            return dataTable;
        }

        /// <summary>
        /// 导出Excel
        /// </summary>
        /// <param name="dataTable">数据源</param>
        /// <param name="heading">工作簿Worksheet</param>
        /// <param name="showSrNo">//是否显示行编号</param>
        /// <param name="columnsToTake">要导出的列</param>
        /// <returns></returns>
        public static byte[] ExportExcel(DataTable dataTable, string heading = "", bool showSrNo = false, params string[] columnsToTake)
        {
            byte[] result;
            using (ExcelPackage package = new ExcelPackage())
            {
                ExcelWorksheet workSheet = package.Workbook.Worksheets.Add($"{heading}Data");
                int startRowFrom = string.IsNullOrEmpty(heading) ? 1 : 3;  //开始的行
                //是否显示行编号
                if (showSrNo)
                {
                    DataColumn dataColumn = dataTable.Columns.Add("#", typeof(int));
                    dataColumn.SetOrdinal(0);
                    int index = 1;
                    foreach (DataRow item in dataTable.Rows)
                    {
                        item[0] = index;
                        index++;
                    }
                }
                //Add Content Into the Excel File
                workSheet.Cells["A" + startRowFrom].LoadFromDataTable(dataTable, true);
                // autofit width of cells with small content  
                int columnIndex = 1;
                foreach (DataColumn item in dataTable.Columns)
                {
                    ExcelRange columnCells = workSheet.Cells[workSheet.Dimension.Start.Row, columnIndex, workSheet.Dimension.End.Row, columnIndex];
                    int maxLength = columnCells.Max(cell => cell.Value.ToString().Count());
                    if (maxLength < 150)
                    {
                        workSheet.Column(columnIndex).AutoFit();
                    }
                    columnIndex++;
                }
                // format header - bold, yellow on black  
                using (ExcelRange r = workSheet.Cells[startRowFrom, 1, startRowFrom, dataTable.Columns.Count])
                {
                    r.Style.Font.Color.SetColor(System.Drawing.Color.White);
                    r.Style.Font.Bold = true;
                    r.Style.Fill.PatternType = ExcelFillStyle.Solid;
                    r.Style.Fill.BackgroundColor.SetColor(System.Drawing.ColorTranslator.FromHtml("#1fb5ad"));
                }
                // format cells - add borders  
                using (ExcelRange r = workSheet.Cells[startRowFrom + 1, 1, startRowFrom + dataTable.Rows.Count, dataTable.Columns.Count])
                {
                    r.Style.Border.Top.Style = ExcelBorderStyle.Thin;
                    r.Style.Border.Bottom.Style = ExcelBorderStyle.Thin;
                    r.Style.Border.Left.Style = ExcelBorderStyle.Thin;
                    r.Style.Border.Right.Style = ExcelBorderStyle.Thin;
                    r.Style.Border.Top.Color.SetColor(System.Drawing.Color.Black);
                    r.Style.Border.Bottom.Color.SetColor(System.Drawing.Color.Black);
                    r.Style.Border.Left.Color.SetColor(System.Drawing.Color.Black);
                    r.Style.Border.Right.Color.SetColor(System.Drawing.Color.Black);
                }
                // removed ignored columns  
                for (int i = dataTable.Columns.Count - 1; i >= 0; i--)
                {
                    if (i == 0 && showSrNo)
                    {
                        continue;
                    }
                    if (!columnsToTake.Contains(dataTable.Columns[i].ColumnName))
                    {
                        workSheet.DeleteColumn(i + 1);
                    }
                }
                if (!string.IsNullOrEmpty(heading))
                {
                    workSheet.Cells["A1"].Value = heading;
                    workSheet.Cells["A1"].Style.Font.Size = 20;
                    workSheet.InsertColumn(1, 1);
                    workSheet.InsertRow(1, 1);
                    workSheet.Column(1).Width = 5;
                }
                result = package.GetAsByteArray();
            }
            return result;
        }
        /// <summary>
        /// 导出Excel
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="data"></param>
        /// <param name="heading"></param>
        /// <param name="isShowSlNo"></param>
        /// <param name="columnsToTake"></param>
        /// <returns></returns>
        public static byte[] ExportExcel<T>(List<T> data, string heading = "", bool isShowSlNo = false, params string[] columnsToTake)
        {
            return ExportExcel(ListToDataTable(data), heading, isShowSlNo, columnsToTake);
        }
    }

二、调用

　　执行后Excel将会保存到D盘

 string strSql = string.Format(@"SELECT TOP 10 [Name] AS 姓名,[PhoneNumber] AS 手机,[Email] AS 邮箱,[Department] AS 部门 FROM [User]");
 DataTable dt = DBHelper.ExecuteTable(strSql);
 string[] columns = { "姓名", "手机", "邮箱", "部门" };
 byte[] filecontent = ExcelExportHelper.ExportExcel(dt, "", false, columns);
 FileStream fs = new FileStream(@"D:\信息.xlsx", FileMode.Create, FileAccess.Write);
 fs.Write(filecontent, 0, filecontent.Length);
 fs.Flush();
 fs.Close();