npoi 导出excel

首先用Vs自带的Nuget包管理器下载并安装npoi 2.0,如果没有NuGet程序包选项，在菜单-->工具-->扩展管理器中搜索NuGet。

然后写一个方法读取DataTable中的内容，并输出到MemoryStream中

这是我的NPOIHelper

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
using System.IO;
using NPOI.HSSF.UserModel;
using NPOI.HPSF;
using System.Text;
using NPOI.SS.Util;
using NPOI.SS.UserModel;

/// <summary>
///NPOIHelper 的摘要说明
/// </summary>
public static class NPOIHelper
{
public static HSSFWorkbook workbook; 
public static void CloseWorkBook()
{
workbook = null;
}
public static void OpenWorkBook() {
workbook = new HSSFWorkbook();
}
/// <summary>
/// DataTable导出到Excel的MemoryStream
/// </summary>
/// <param name="dtSource">源DataTable</param>
/// <param name="strHeaderText">表头文本</param>
public static void Export(DataTable dtSource, string strHeaderText) {

HSSFSheet sheet = (HSSFSheet)workbook.CreateSheet();

#region 右击文件 属性信息
{
DocumentSummaryInformation dsi = PropertySetFactory.CreateDocumentSummaryInformation();
dsi.Company = "北京通信科技有限公司";
workbook.DocumentSummaryInformation = dsi;

SummaryInformation si = PropertySetFactory.CreateSummaryInformation();
//si.Author = "文件作者信息"; //填加xls文件作者信息
//si.ApplicationName = "创建程序信息"; //填加xls文件创建程序信息
//si.LastAuthor = "最后保存者信息"; //填加xls文件最后保存者信息
//si.Comments = "作者信息"; //填加xls文件作者信息
//si.Title = "标题信息"; //填加xls文件标题信息
//si.Subject = "主题信息";//填加文件主题信息
si.CreateDateTime = DateTime.Now;
workbook.SummaryInformation = si;
}
#endregion

HSSFCellStyle dateStyle = (HSSFCellStyle)workbook.CreateCellStyle();
HSSFDataFormat format = (HSSFDataFormat)workbook.CreateDataFormat();
dateStyle.DataFormat = format.GetFormat("yyyy-mm-dd");

HSSFCellStyle tdStyle = (HSSFCellStyle)workbook.CreateCellStyle();
//设置单元格边框 
tdStyle.VerticalAlignment = VerticalAlignment.CENTER;//垂直居中
tdStyle.BorderBottom = BorderStyle.THIN;
tdStyle.BorderLeft = BorderStyle.THIN;
tdStyle.BorderRight = BorderStyle.THIN;
tdStyle.BorderTop = BorderStyle.THIN;
//取得列宽
int[] arrColWidth = new int[dtSource.Columns.Count];
foreach (DataColumn item in dtSource.Columns) {
arrColWidth[item.Ordinal] = Encoding.GetEncoding(936).GetBytes(item.ColumnName.ToString()).Length;
}
for (int i = 0; i < dtSource.Rows.Count; i++) {
for (int j = 0; j < dtSource.Columns.Count; j++) {
int intTemp = Encoding.GetEncoding(936).GetBytes(dtSource.Rows[i][j].ToString()).Length;
if (intTemp > arrColWidth[j]) {
arrColWidth[j] = intTemp;
}
}
}
int rowIndex = 0;
foreach (DataRow row in dtSource.Rows) {
#region 新建表，填充表头，填充列头，样式
if (rowIndex == 65535 || rowIndex == 0) {
if (rowIndex != 0) {
sheet = (HSSFSheet)workbook.CreateSheet();
}

#region 表头及样式
{
HSSFRow headerRow = (HSSFRow)sheet.CreateRow(0);
headerRow.HeightInPoints = 25;
headerRow.CreateCell(0).SetCellValue(strHeaderText);

HSSFCellStyle headStyle = (HSSFCellStyle)workbook.CreateCellStyle();
headStyle.Alignment = HorizontalAlignment.CENTER;
HSSFFont font = (HSSFFont)workbook.CreateFont();

font.FontHeightInPoints = 20;
font.Boldweight = 700;
headStyle.SetFont(font);
headerRow.GetCell(0).CellStyle = headStyle;
sheet.AddMergedRegion(new CellRangeAddress(0, 0, 0, dtSource.Columns.Count - 1));
//headerRow.Dispose();
}
#endregion


#region 列头及样式
{
HSSFRow headerRow = (HSSFRow)sheet.CreateRow(1);
HSSFCellStyle headStyle = (HSSFCellStyle)workbook.CreateCellStyle();
headStyle.Alignment = HorizontalAlignment.CENTER;
HSSFFont font = (HSSFFont)workbook.CreateFont();
//设置单元格边框 
headStyle.BorderBottom = BorderStyle.THIN;
headStyle.BorderLeft = BorderStyle.THIN;
headStyle.BorderRight = BorderStyle.THIN;
headStyle.BorderTop = BorderStyle.THIN;

font.FontHeightInPoints = 10;
font.Boldweight = 700;
headStyle.SetFont(font);
foreach (DataColumn column in dtSource.Columns) {
headerRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);
headerRow.GetCell(column.Ordinal).CellStyle = headStyle;

//设置列宽
sheet.SetColumnWidth(column.Ordinal, (arrColWidth[column.Ordinal] + 1) * 256);
}
//headerRow.Dispose();
}
#endregion

rowIndex = 2;
}
#endregion


#region 填充内容
HSSFRow dataRow = (HSSFRow)sheet.CreateRow(rowIndex);
foreach (DataColumn column in dtSource.Columns) {
HSSFCell newCell = (HSSFCell)dataRow.CreateCell(column.Ordinal);
newCell.CellStyle = tdStyle;

string drValue = row[column].ToString();
switch (column.DataType.ToString()) {
case "System.String"://字符串类型
newCell.SetCellValue(drValue);
break;
case "System.DateTime"://日期类型
DateTime dateV;
DateTime.TryParse(drValue, out dateV);
newCell.SetCellValue(dateV);

newCell.CellStyle = dateStyle;//格式化显示
break;
case "System.Boolean"://布尔型
bool boolV = false;
bool.TryParse(drValue, out boolV);
newCell.SetCellValue(boolV);
break;
case "System.Int16"://整型
case "System.Int32":
case "System.Int64":
case "System.Byte":
int intV = 0;
int.TryParse(drValue, out intV);
newCell.SetCellValue(intV);
break;
case "System.Decimal"://浮点型
case "System.Double":
double doubV = 0;
double.TryParse(drValue, out doubV);
newCell.SetCellValue(doubV);
break;
case "System.DBNull"://空值处理
newCell.SetCellValue("");
break;
default:
newCell.SetCellValue("");
break;
}

}
#endregion

rowIndex++;
}
using (MemoryStream ms = new MemoryStream()) {
workbook.Write(ms);
}
}

public static MemoryStream Export2(DataTable dt, string p) {
Export(dt,p);
MemoryStream ms = new MemoryStream();
ISheet sheet=workbook.GetSheet("Sheet1");
int FirstRow=2;
int LastRow=sheet.LastRowNum;
int Start=0;
int End=0;
string temp = "";
HSSFCellStyle dateStyle = (HSSFCellStyle)workbook.CreateCellStyle();
dateStyle.Alignment = HorizontalAlignment.RIGHT;
dateStyle.VerticalAlignment = VerticalAlignment.CENTER;
for (int i = FirstRow; i < LastRow; i++) {
for (int j = 1; j < 5; j++) {
if (j == 1)
{
IRow row=sheet.GetRow(i);
if (row == null) continue; //没有数据的行默认是null
if (row.GetCell(j) == null){continue;} //同理，没有数据的单元格都默认是null
ICell cell=row.GetCell(j);
string cellText=cell.StringCellValue;
if (cellText == temp)//上下行相等，记录要合并的最后一行
{
End = i;
}
else//上下行不等，记录
{
if (Start != End) {
for (int n = Start; n < End; n++) {
ICell tempcell=sheet.GetRow(n).GetCell(2);
tempcell.SetCellValue(""+( End-Start+1 ));
tempcell.CellStyle = dateStyle;
}
for (int m = 1; m < 5; m++) {
CellRangeAddress region = new CellRangeAddress(Start, End, m,m);
sheet.AddMergedRegion(region);
}

}
Start = i;
End = i;
temp = cellText;
}
}

}
}
workbook.Write(ms);
return ms;
}
}

 使用方法是:

NPOIHelper.OpenWorkBook();
DataTable dt=EconomicHelper4.GetSumProjectManager();
NPOIHelper.Export(dt,“管理");　　　　　　　　　　　　　　　　　　　　　　    //Export1用于生成DataTable
DataTable dt2 = EconomicHelper4.GetExtensionProjectManager();
MemoryStream ms = NPOIHelper.Export2(dt2, "数据");  　　　　　　　　　　//Export2用于合并单元格　　
Response.AddHeader("Content-Disposition", string.Format("attachment; filename={0}.xls", DateTime.Now.ToString("yyyyMMddHHmmssfff")));
Response.BinaryWrite(ms.ToArray());
ms.Close();
ms.Dispose();
NPOIHelper.CloseWorkBook();