数据导入Excel表格

后台代码：  

using BLL;
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.IO.MemoryMappedFiles;
using System.Linq;
using System.Web;
using System.Web.UI;

namespace EasyUI
{
    /// <summary>
    /// ExcelHandler 的摘要说明
    /// </summary>
    public class ExcelHandler : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            try
            {
                DataTable dt = new DataTable();
                dt = Service.Excel();//数据源
                string strFileName = "Excel";
                //创建空excel文件
                HSSFWorkbook workbook = new HSSFWorkbook();
                ISheet sheet = string.IsNullOrEmpty(strFileName) ? workbook.CreateSheet("Sheet1") : workbook.CreateSheet(strFileName);
                //表头
                IRow row = sheet.CreateRow(0);
                for (int i = 0; i < dt.Columns.Count; i++)
                {
                    ICell cell = row.CreateCell(i);
                    cell.SetCellValue(dt.Columns[i].ColumnName);
                    //创建列头的样式
                    HSSFCellStyle cellStyle = (HSSFCellStyle)workbook.CreateCellStyle();
                    //居中显示
                    cellStyle.Alignment = HorizontalAlignment.Center;
                    //垂直居中
                    cellStyle.VerticalAlignment = VerticalAlignment.Center;
                    HSSFFont font = (HSSFFont)workbook.CreateFont();
                    font.FontHeightInPoints = 12;
                    font.FontName = "宋体";
                    font.IsBold = true;
                    cellStyle.SetFont(font);
                    cell.CellStyle = cellStyle;
                }
                //数据
                int[] len = new int[dt.Columns.Count];
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    //行
                    IRow rows = sheet.CreateRow(i + 1);
                    for (int j = 0; j < dt.Columns.Count; j++)
                    {
                        //列
                        ICell cell = rows.CreateCell(j);
                        cell.SetCellValue(dt.Rows[i][j].ToString());
                        var lenTemp = dt.Rows[i][j].ToString().Length > dt.Columns[j].ColumnName.Length ? dt.Rows[i][j].ToString().Length : dt.Columns[j].ColumnName.Length;
                        if (lenTemp > len[j])
                        {
                            len[j] = lenTemp;
                        }
                    }
                }
                //自动设置列宽
                for (int i = 0; i < len.Length; i++)
                {
                    if (len[i] < 8)
                    {
                        len[i] = Convert.ToInt32(Math.Round(len[i] * 2.5));
                    }
                    else
                    {
                        len[i] = Convert.ToInt32(Math.Round(len[i] * 1.3));
                    }
                    sheet.SetColumnWidth(i, len[i] * 256);
                }
                string fileName = strFileName + DateTime.Now.ToString("yyMMddHHmmssfff") + ".xls";
                //写入到客户端
                MemoryStream ms = new MemoryStream(); //创建其支持存储区为内存的流
                //数据写入流中
                workbook.Write(ms);
                // 设置当前流的位置为流的开始
                ms.Seek(0, SeekOrigin.Begin);
                //防止中文乱码
                fileName = HttpUtility.UrlEncode(fileName);
                //设置输出编码格式
                //context.Response.ContentEncoding = System.Text.Encoding.UTF8;
                //设置输出流
                context.Response.ContentType = "application/vnd.ms-excel";
                //// 限制类型 
                //context.Response.AddHeader("content-type", "application/vnd.ms-excel");
                //下载后文件名
                context.Response.AddHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8)); 
                workbook = null;
                ms.Close();
                ms.Dispose();
                //实现文件下载
                context.Response.BinaryWrite(ms.ToArray());
               
            }
            catch (Exception ex)

            {

                context.Response.Write(ex.Message);

            }
            //ExportDataSetToExcel(dt, fileName, "sheet1");
        }
        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

返回前台后：  window.open("ExcelHandler.ashx");//打开浏览器窗口

别忘记在项目中引用NPOI