.Net读取Excel 返回DataTable实例代码

代码如下:
using System;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
using System.Data;
using System.IO;
using System.Linq;
using System.Web;
using System.Collections;
using System.Data.OleDb;
using NuctechProject.DTO.Bll;
using System.Collections.Generic;
namespace NuctechProject.Layouts.Project
{
    public partial class IntroductionPlan : LayoutsPageBase
    {
        string url = Common.rootUrl;
        private string _strConn; //导入excel时的连接
        string pmurl = Common.proUrl;
        private UserBLL bll = new UserBLL();
        protected void Page_Load(object sender, EventArgs e)
        {
            hidProid.Value = Request.QueryString["proid"];
        }
        protected void BtnOK_Click(object sender, EventArgs e)
        {
            DataTable excelTable = null;

            SPSecurity.RunWithElevatedPrivileges(delegate
            {
                if (BaseInfoTemplateFile.HasFile)
                {
                    List<string> noInput = new List<string>();
                    string strLoginName = HttpContext.Current.User.Identity.Name; //获取用户名
                    string folderTemp = strLoginName.Substring(strLoginName.LastIndexOf('//') + 1);
                    try
                    {
                        string extension = Path.GetExtension(BaseInfoTemplateFile.FileName); //获取文件的后缀
                        if (extension != null)
                        {