先上测试代码:
string connectionString = "Server=localhost;Initial Catalog=******;User ID=sa;Password=******;";
List<TestData> datas = null;
using (SqlConnection db = new SqlConnection(connectionString))
{
datas = db.Query<TestData>("SELECT * FROM TestData").ToList();
}
System.Console.WriteLine($"数据源对象 {typeof(TestData).GetProperties().Length} 个字段,共 {datas.Count} 条记录,大小 {BinarySerializeHelper.SerializeToBytes(datas).Length/1000/1000} M");
Task.Run(() =>
{
while (true)
{
System.Console.WriteLine($"{DateTime.Now} 内存 : {GC.GetTotalMemory(false) / 1000 / 1000} M");
Thread.Sleep(1000);
}
});
Stopwatch sw = new Stopwatch();
sw.Start();
byte[] bytes = ExcelHandlerFactory.CreateHandler(datas).CreateExcelBytes();
sw.Stop();
System.Console.WriteLine($"{DateTime.Now} 数据源转Excel文件字节数组耗时 : "+sw.ElapsedMilliseconds / 1000 +" 秒");
string path = @"C:\Users\Administrator\Desktop\1.xlsx";
FileStream fs = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write);
fs.Write(bytes);
fs.Dispose();
System.Console.ReadKey();
测试结果:
就是这内存占用有点高......
源码:
using System.Collections.Generic;
namespace Wjire.Excel
{
/// <summary>
/// ExcelHandler工厂
/// </summary>
public static class ExcelHandlerFactory
{
/// <summary>
/// 创建ExcelHandler
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="sources">数据源</param>
/// <param name="choosedFields">需要导出的字段,可不传,则导出所有字段</param>
/// <returns></returns>
public static ExcelHandler<T> CreateHandler<T>(IEnumerable<T> sources, HashSet<string> choosedFields = null)
{
return new ExcelHandler<T>(sources, choosedFields);
}
}
}
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
namespace Wjire.Excel
{
/// <summary>
/// 报表导出处理者
/// </summary>
public sealed class ExcelHandler<TSource>
{
/// <summary>
/// 数据源
/// </summary>
private readonly IEnumerable<TSource> _sources;
/// <summary>
/// 需要导出的列信息
/// </summary>
private readonly ColumnInfo[] _columnInfos;
/// <summary>
/// 工作簿
/// </summary>
private IWorkbook _workbook;
/// <summary>
/// 工作页
/// </summary>
private ISheet _sheet;
/// <summary>
/// 单元格样式
/// </summary>
private ICellStyle _cellStyle;
/// <summary>
/// 单元格样式提供器
/// </summary>
private ICellStyleProvider _provider;
internal ExcelHandler(IEnumerable<TSource> sources, HashSet<string> choosedFields)
{
_sources = sources;
_columnInfos = GetColumnInfosOfExport(choosedFields);
}
/// <summary>
/// 数据源转字节
/// </summary>
/// <returns></returns>
public byte[] CreateExcelBytes()
{
using (var ms = CreateExcelStream())
{
return ms.ToArray();
}
}
/// <summary>
/// 数据源转excel流
/// </summary>
/// <returns></returns>
public MemoryStream CreateExcelStream()
{
try
{
_workbook = new HSSFWorkbook();
_cellStyle = (_provider ?? DefaultCellStyleProvider.Singleton.Value).CreateCellStyle(_workbook);
int sheetIndex = 1;
CreateSheetWithHeader(sheetIndex);
int rowIndex = 1;
foreach (TSource entity in _sources)
{
//03版 excel 一个 _sheet 最多 65535 行
if (rowIndex == 65535)
{
sheetIndex++;
CreateSheetWithHeader(sheetIndex);
rowIndex = 1;
}
CreateDataRow(rowIndex, entity);
rowIndex++;
}
MemoryStream ms = new MemoryStream();
_workbook.Write(ms);
return ms;
}
finally
{
_workbook?.Close();
}
}
/// <summary>
/// 创建Sheet及列头
/// </summary>
private void CreateSheetWithHeader(int sheetIndex)
{
_sheet = _workbook.CreateSheet("第 " + sheetIndex + " 页");
//冻结首行首列
_sheet.CreateFreezePane(0, 1);
IRow header = _sheet.CreateRow(0);
for (int i = 0; i < _columnInfos.Length; i++)
{
ICell cell = header.CreateCell(i);
cell.SetCellValue(_columnInfos[i].CellDisplayAttribute.Name);
cell.CellStyle = _cellStyle;
//自适应宽度
_sheet.AutoSizeColumn(i);
}
}
/// <summary>
/// 创建数据行
/// </summary>
/// <param name="rowIndex">行索引</param>
/// <param name="entity">数据</param>
private void CreateDataRow(int rowIndex, object entity)
{
IRow dataRow = _sheet.CreateRow(rowIndex);
for (int i = 0; i < _columnInfos.Length; i++)
{
ICell cell = dataRow.CreateCell(i);
cell.CellStyle = _cellStyle;
object value = _columnInfos[i].PropertyInfo.GetValue(entity, null);
SetCellValue(value, cell);
}
}
/// <summary>
/// 设置单元格值
/// </summary>
/// <param name="value"></param>
/// <param name="cell"></param>
private void SetCellValue(object value, ICell cell)
{
if (value == null)
{
cell.SetCellValue(string.Empty);
return;
}
Type type = value.GetType();
switch (type.Name)
{
case "DateTime":
case "String":
case "Boolean":
cell.SetCellValue(value.ToString());
break;
case "Byte":
case "Int16":
case "Int32":
case "Int64":
case "Single":
case "Double":
case "Decimal":
cell.SetCellValue(Convert.ToDouble(value));
break;
default:
cell.SetCellValue(string.Empty);
break;
}
}
/// <summary>
/// 设置excel单元格样式提供器
/// </summary>
/// <param name="provider"></param>
/// <returns></returns>
public ExcelHandler<TSource> SetCellStyleProvider(ICellStyleProvider provider)
{
_provider = provider;
return this;
}
/// <summary>
/// 获取需要导出的列信息
/// </summary>
/// <param name="choosedFields"></param>
/// <returns></returns>
private ColumnInfo[] GetColumnInfosOfExport(HashSet<string> choosedFields)
{
ColumnInfo[] columnInfos = ColumnInfoContainer.GetColumnInfo(typeof(TSource));
return choosedFields?.Count > 0
? columnInfos.Where(w => choosedFields.Contains(w.PropertyInfo.Name)).ToArray()
: columnInfos;
}
}
}
using System.Reflection;
namespace Wjire.Excel
{
/// <summary>
/// 列信息
/// </summary>
public class ColumnInfo
{
internal PropertyInfo PropertyInfo { get; set; }
internal CellDisplayAttribute CellDisplayAttribute { get; set; }
}
}
using System;
namespace Wjire.Excel
{
/// <summary>
/// excel 单元格数据显示自定义特性类
/// </summary>
[AttributeUsage(AttributeTargets.Property)]
public sealed class CellDisplayAttribute : Attribute
{
/// <summary>
/// 自定义列名
/// </summary>
public string Name { get; set; }
/// <summary>
/// 构造函数
/// </summary>
/// <param name="name">自定义列名</param>
public CellDisplayAttribute(string name)
{
Name = name;
}
}
}
using NPOI.SS.UserModel;
namespace Wjire.Excel
{
/// <summary>
/// 单元格样式提供器接口
/// </summary>
public interface ICellStyleProvider
{
ICellStyle CreateCellStyle(IWorkbook workbook);
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
namespace Wjire.Excel
{
/// <summary>
/// 数据源列信息容器
/// </summary>
internal static class ColumnInfoContainer
{
private static readonly Dictionary<Type, ColumnInfo[]> Container = new Dictionary<Type, ColumnInfo[]>();
/// <summary>
/// 获取数据源列信息
/// </summary>
/// <param name="sourceType">数据源类类型</param>
/// <returns></returns>
internal static ColumnInfo[] GetColumnInfo(Type sourceType)
{
if (Container.TryGetValue(sourceType, out ColumnInfo[] infos))
{
return infos;
}
infos = sourceType
.GetProperties(BindingFlags.Public | BindingFlags.Instance)
.Where(propertyInfo => propertyInfo.GetCustomAttribute<CellDisplayAttribute>(true) != null)
.Select(propertyInfo => new ColumnInfo
{
PropertyInfo = propertyInfo,
CellDisplayAttribute = propertyInfo.GetCustomAttribute<CellDisplayAttribute>()
}).ToArray();
Container.Add(sourceType, infos);
return infos;
}
}
}
using NPOI.SS.UserModel;
using System;
namespace Wjire.Excel
{
/// <summary>
/// 默认单元格样式提供器
/// </summary>
internal class DefaultCellStyleProvider : ICellStyleProvider
{
internal static Lazy<DefaultCellStyleProvider> Singleton = new Lazy<DefaultCellStyleProvider>(() => new DefaultCellStyleProvider());
private DefaultCellStyleProvider()
{
}
/// <summary>
/// 创建单元格样式
/// </summary>
/// <param name="workbook"></param>
/// <returns></returns>
public ICellStyle CreateCellStyle(IWorkbook workbook)
{
ICellStyle cellStyle = workbook.CreateCellStyle();
cellStyle.Alignment = HorizontalAlignment.Center;
//cellStyle.VerticalAlignment = VerticalAlignment.Center;//垂直居中非常影响效率,不建议打开该功能
IFont font = workbook.CreateFont();
font.FontHeightInPoints = 11;
//font.Boldweight = 700;
cellStyle.SetFont(font);
//边框
//cellStyle.BorderBottom = BorderStyle.Thin;
//cellStyle.BorderLeft = BorderStyle.Thin;
//cellStyle.BorderRight = BorderStyle.Thin;
//cellStyle.BorderTop = BorderStyle.Thin;
return cellStyle;
}
}
}
几点说明:
1.NPOI 用的最新版本:2.4.1;
2.代码中用的 HSSFWorkbook ,不仅仅是为了兼容 word2003,在测试的时候发现,如果用 XSSFWorkbook ,耗时慢了N个数量级,不知道是不是哪里姿势不对;
3.单元格的宽度只在标题栏设置了,所以导出来的Excel可能比较丑.原因是:
1)如果根据单元格内容的长度来调整的话,由于每一个单元格内容的长度都肯能不一样,太耗时,没必要,不如鼠标点两下来得快;
2)虽然NPOI有个功能可以在一个sheet的数据填充完后,设置单元格的宽度自适应,但是测试了下,太太太太慢了.估计是在遍历所有的单元格,一个一个计算;
3)还有一个折中的办法,就是根据第一行数据的各个单元格内容来调整宽度,因为有些时候,数据对象每个属性的值的长度都不会差太多.但是当长度不一的时候,会让人误以为那些长的单元格的内容已经显示完了,所以也舍弃了这个功能.
4.测试的时候发现,如果把某一列的单元格设置成超链接,点击可以打开浏览器查看那种,非常非常非常非常慢.惨不忍睹.不知道是不是姿势不对,所以也舍弃了该功能.