NPOI大数据量多个sheet导出源码（原）

#region  NPOI大数据量多个sheet导出

/// <summary>
/// 大数据量多个sheet导出
/// </summary>
/// <typeparam name="T">数据源实体类</typeparam>
/// <param name="objList">数据源</param>
/// <param name="fileName">文件名称</param>
/// <param name="btyBytes">导出数据流</param>
/// <param name="columnInfo">显示列对应数据字典</param>
/// <param name="listCount">每个sheet包含数据条数</param>
/// <returns></returns>
public static bool ExportExcelTest<T>(List<T> objList, string fileName, ref byte[] btyBytes,
　　　　　　　　　　　　　　　　　　　　　　　　　　Dictionary<string, string> columnInfo = null,int listCount=10000)
{
bool bResult = false;
//在内存中生成一个Excel文件：
HSSFWorkbook book = new HSSFWorkbook();
if (objList != null && objList.Count > 0)
{
double sheetCount = Math.Ceiling((double)objList.Count / listCount);
for (int i = 0; i < sheetCount; i++)
{
ISheet sheet = null;
sheet = book.CreateSheet("sheet" + i);
sheet.DefaultRowHeight = 20 * 10;
List<T> list = new List<T>();
list = objList.Skip<T>(listCount * i).Take<T>(listCount).ToList();

int rowIndex = 0;
int StartColIndex = 0;
int colIndex = StartColIndex;

//创建表头样式
ICellStyle style = book.CreateCellStyle();
style.Alignment = HorizontalAlignment.Center;
style.WrapText = true;
IFont font = book.CreateFont();
font.FontHeightInPoints = 16;
font.Boldweight = (short)NPOI.SS.UserModel.FontBoldWeight.Bold;
font.FontName = "简体中文";
style.SetFont(font);//HEAD 样式

Type myType = null;
myType = objList[0].GetType();
//根据反射从传递进来的属性名信息得到要显示的属性
List<PropertyInfo> myPro = new List<PropertyInfo>();
PropertyInfo[] properties = myType.GetProperties();

#region 定义表头
int m = 0;
if (columnInfo != null)
{
var rowheader = sheet.CreateRow(0);
rowheader.Height = rowheader.Height = 20 * 20;
foreach (string cName in columnInfo.Keys)
{
PropertyInfo p = myType.GetProperty(cName);
if (p != null)
{
myPro.Add(p);
rowheader.CreateCell(m).SetCellValue(columnInfo[cName]);
m++;
}
}
}
#endregion
#region 定义表体并赋值
//如果没有找到可用的属性则结束
if (myPro.Count == 0) { return bResult; }
foreach (T obj in list)
{
int n = 0;
if (sheet != null)
{
rowIndex++;
var sheetrow = sheet.CreateRow(rowIndex);
sheetrow.Height = sheetrow.Height = 20 * 20;
foreach (PropertyInfo p in myPro)
{
dynamic val = p.GetValue(obj, null) ?? "";
string valtype = val.GetType().ToString();
if (valtype.ToLower().IndexOf("decimal", StringComparison.Ordinal) > -1)
{
val = Convert.ToDouble(val);
}
else if (valtype.ToLower().IndexOf("datetime", StringComparison.Ordinal) > -1)
{
val = val.ToString("yyyy-MM-dd HH:mm:ss");
if (val.Equals("0001-01-01 00:00:00"))
{
val = "";
}
}
sheetrow.CreateCell(n).SetCellValue(val);
n++;
}
}

}
#endregion
}
}
else
{
//在工作薄中建立工作表
HSSFSheet sheet = book.CreateSheet() as HSSFSheet;
sheet.SetColumnWidth(0, 30 * 256);
if (sheet != null) sheet.CreateRow(0).CreateCell(0).SetCellValue("暂无数据！");
}

try
{
HttpResponse rs = System.Web.HttpContext.Current.Response;
rs.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
rs.AppendHeader("Content-Disposition", "attachment;filename=" + fileName);
rs.ContentType = "application/ms-excel";
using (MemoryStream ms = new MemoryStream())
{
book.Write(ms);
rs.BinaryWrite(ms.ToArray());
ms.Flush();
}
}
catch (SystemException ex)
{
LogHelper.Write(ex);
}
catch (ApplicationException ex)
{
LogHelper.Write(ex);
}
return bResult;
}

#endregion