asp.net合并excel

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.OleDb; //导入命名空间
using System.IO;
using Excel = Microsoft.Office.Interop.Excel;
using System.Reflection;
using System.Data;
using EnterExcel.BLL;
using EnterExcel.Models;
public partial class JoinExcel : System.Web.UI.Page
{
 protected void Page_Load(object sender, EventArgs e)
 {
  if (!IsPostBack) { }
 }
 private static List<string> listFiles = new List<string>();
 List<Pencil> pencilList = new List<Pencil>();
 //“将Excel添加到集合中”事件
 protected void btnAdd_Click(object sender, EventArgs e)
 {
  listFiles.Add(this.fuSearchExcel.PostedFile.FileName);
 }
 //“导入Excel到界面”事件
 protected void btnJoinExcel_Click(object sender, EventArgs e)
 {
  //遍历集合
  foreach (string listFile in listFiles)
  {
   //将Excel路径循环赋给方法
   DataTable dt = CreateDataSource(listFile);
   foreach (DataRow row in dt.Rows)
   {
    Pencil pencil = new Pencil();
    pencil.Name = row[0].ToString();
    pencil.Type = row[1].ToString();
    pencil.Number = row[2].ToString();
    pencil.Unit = row[3].ToString();
    pencilList.Add(pencil);
   }
  }
  this.gvInfo.DataSource = LoadExcelFiles(pencilList);
  this.gvInfo.DataBind();
  listFiles.Clear();
 }
 List<Pencil> list = new List<Pencil>();
 public List<Pencil> LoadExcelFiles(List<Pencil> pencilList)
 {
  Pencil p = null;
  for (int i = 0; i < pencilList.Count; i++)