.net core 转 excel datatable list<t> 互转 xlsx

using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Threading.Tasks;
using Castle.Core.Internal;
using Microsoft.AspNetCore.Http;
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using OfficeOpenXml;

namespace Gaea.OfficeManagement
{
public static class ExcelHelper
{

public static DataTable ExcelToTable (Stream ExcelFileStream, int SheetIndex, int HeaderRowIndex)
{
ExcelPackage package = new ExcelPackage(ExcelFileStream);
ExcelPackage.LicenseContext = OfficeOpenXml.LicenseContext.Commercial;
ExcelWorksheet worksheet = package.Workbook.Worksheets[SheetIndex];//选定 指定页

int rows = worksheet.Dimension.End.Row;
//获取worksheet的列数
int cols = worksheet.Dimension.End.Column;

DataTable dt = new DataTable(worksheet.Name);
DataRow dr = null;
for (int i = HeaderRowIndex; i <= rows; i++)
{
if (i > 1)
dr = dt.Rows.Add();

for (int j = 1; j <= cols; j++)
{
//默认将第一行设置为datatable的标题
if (i == HeaderRowIndex)
dt.Columns.Add(GetString(worksheet.Cells[i, j].Value));
//剩下的写入datatable
else
dr[j - 1] = GetString(worksheet.Cells[i, j].Value);
}
}
return dt;
}

private static string GetString(object obj)
{
try
{
return obj.ToString();
}
catch (Exception ex)
{
return "";
}
}

/// <summary>
/// 将excel转换为datatable
/// </summary>
/// <param name="filePaht">文件路径</param>
/// <param name="startRow">读取数据的起始行</param>
/// <returns>DataTable</returns>
public static DataTable ExcelToDataTable(IFormFile file, int startRow)
{

MemoryStream ms = new MemoryStream();
file.CopyTo(ms);
ms.Seek(0, SeekOrigin.Begin);

//声明一个变量
ISheet sheet = null;
DataTable data = new DataTable();
//int startRow = 3;
try
{
//读取excel文件
//FileStream fs = new FileStream(filePaht, FileMode.Open, FileAccess.Read);
IWorkbook workbook = new XSSFWorkbook(ms);
//读取excel的第一个sheet页
sheet = workbook.GetSheetAt(0);
if (sheet != null)
{
//起始行
IRow firstRow = sheet.GetRow(startRow);
int cellCount = firstRow.LastCellNum; //一行最后一个cell的编号 即总的列数
//循环添加列
for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
{
//如果导入的是端午活动的手机号码
if(startRow==1)
{
firstRow.Cells[0].SetCellType(CellType.String);
}

//添加列
DataColumn column = new DataColumn(firstRow.GetCell(i).StringCellValue);
data.Columns.Add(column);
}
//最后一列的标号
int rowCount = sheet.LastRowNum;
for (int i = startRow+1; i <= rowCount; ++i)
{
IRow row = sheet.GetRow(i);
if (row == null) continue; //没有数据的行默认是null　　　　　　　

//创建行
DataRow dataRow = data.NewRow();
int index = 0;
for (int j = row.FirstCellNum; j < cellCount; ++j)
{
//填充列
dataRow[index] = row.GetCell(j)?.ToString();
index++;
}
//填充行
data.Rows.Add(dataRow);
}
}
return data;
}
catch (Exception ex)
{
Console.WriteLine("Exception: " + ex.Message);
return null;
}
}

public static async Task<MemoryStream> ExportAsync(this DataTable table)
{
var stream = new MemoryStream();

//如果您在非商业环境中使用EPPlus
//根据Polyform非商业许可证：
ExcelPackage.LicenseContext = OfficeOpenXml.LicenseContext.NonCommercial;

using (ExcelPackage package = new ExcelPackage())
{
// add a new worksheet to the empty workbook
ExcelWorksheet worksheet = package.Workbook.Worksheets.Add("Sheet1");
//First add the headers
for (int i = 1; i <= table.Columns.Count; i++)
{
worksheet.Cells[1, i].Value = $"{(table.Columns[i - 1].Caption.IsNullOrWhiteSpace() ? table.Columns[i - 1].ColumnName : table.Columns[i - 1].Caption)}";
worksheet.Cells[1, i].Style.Font.Bold = true;
}
//worksheet.Cells[1, 1].Value = "ID";
//worksheet.Cells[1, 2].Value = "Name";
//worksheet.Cells[1, 3].Value = "Gender";
//worksheet.Cells[1, 4].Value = "Salary (in $)";

for (int i = 2; i <= table.Rows.Count; i++)
{
for (int j = 1; j <= table.Columns.Count; j++)
{
worksheet.Cells[i, j].Value = $"{table.Rows[i - 2][j - 1]}";
}
}

////Add values
//worksheet.Cells["A2"].Value = 1000;
//worksheet.Cells["B2"].Value = "Jon";
//worksheet.Cells["C2"].Value = "M";
//worksheet.Cells["D2"].Value = 5000;

//worksheet.Cells["A3"].Value = 1001;
//worksheet.Cells["B3"].Value = "Graham";
//worksheet.Cells["C3"].Value = "M";
//worksheet.Cells["D3"].Value = 10000;

//worksheet.Cells["A4"].Value = 1002;
//worksheet.Cells["B4"].Value = "Jenny";
//worksheet.Cells["C4"].Value = "F";
//worksheet.Cells["D4"].Value = 5000;

//package.Save(); //Save the workbook.
await package.SaveAsAsync(stream);

stream.Seek(0, SeekOrigin.Begin);//没这句话就格式错

return stream;
}
}

public static DataTable ToDataTable<T>(this IEnumerable<T> collection)
{
var props = typeof(T).GetProperties();
var dt = new DataTable();
dt.Columns.AddRange(props.Select(p =>
{
var col = new DataColumn(p.Name, p.PropertyType);

var attrdisplay = p.GetAttributes<DisplayAttribute>().FirstOrDefault();
if (attrdisplay != default)
{
if (!string.IsNullOrWhiteSpace(attrdisplay.Name))
{
col.Caption = attrdisplay.Name;
}
else

if (!string.IsNullOrWhiteSpace(attrdisplay.ShortName))
{
col.Caption = $"{attrdisplay.ShortName}";
}
else if (!string.IsNullOrWhiteSpace(attrdisplay.Description))
{
col.Caption = attrdisplay.Description;
}
}

var attrdisplayname = p.GetAttributes<DisplayNameAttribute>().FirstOrDefault();
if (attrdisplayname != default && !string.IsNullOrWhiteSpace(attrdisplayname.DisplayName))
{
col.Caption = $"{attrdisplayname.DisplayName}";
}

var attrdesc = p.GetAttributes<DescriptionAttribute>().FirstOrDefault();
if (attrdesc != default && !string.IsNullOrWhiteSpace(attrdesc.Description))
{
col.Caption = $"{attrdesc.Description}";
}

var attrcol = p.GetAttributes<ColumnAttribute>().FirstOrDefault();
if (attrcol != default && !string.IsNullOrWhiteSpace(attrcol.Name))
{
col.Caption = $"{attrcol.Name}";
}

return col;
}).ToArray());
if (collection.Count() > 0)
{
for (int i = 0; i < collection.Count(); i++)
{
ArrayList tempList = new ArrayList();
foreach (PropertyInfo pi in props)
{
object obj = pi.GetValue(collection.ElementAt(i), null);
tempList.Add(obj);
}
object[] array = tempList.ToArray();
dt.LoadDataRow(array, true);
}
}
return dt;
}

}
}