一个关于Excel的处理类（部分参考网络上）

using  System;
using  System.Data;
using  System.Configuration;
using  System.Web;
using  System.Web.Security;
using  System.Web.UI;
using  System.Web.UI.WebControls;
using  System.Web.UI.WebControls.WebParts;
using  System.Web.UI.HtmlControls;
using  System.Data.OleDb;
using  System.IO;
namespace  Northwind.Web.common
{
     public   class  ExcelHelper
    {
         // 将控件转换为Excel表
         public   static   void  ExportToExcel(Control c,  string  fileName)
        {
            HttpContext.Current.Response.Clear();
            HttpContext.Current.Response.Buffer  =   true ;
            HttpContext.Current.Response.Charset  =   " utf-7 " ; // 不行就改为utf-7
            HttpContext.Current.Response.AppendHeader( " Content-Disposition " ,  string .Format( " attachment;filename={0}.xls " , fileName));
            HttpContext.Current.Response.ContentEncoding  =  System.Text.Encoding.GetEncoding( " utf-7 " ); // 设置输出流为简体中文
            HttpContext.Current.Response.ContentType  =   " application/ms-excel " ; // 设置输出文件类型为excel文件。
             // this.EnableViewState = false;
            System.Globalization.CultureInfo myCItrad  =   new  System.Globalization.CultureInfo( " ZH-CN " ,  true );
            System.IO.StringWriter oStringWriter  =   new  System.IO.StringWriter(myCItrad);
            System.Web.UI.HtmlTextWriter oHtmlTextWriter  =   new  System.Web.UI.HtmlTextWriter(oStringWriter);
            c.RenderControl(oHtmlTextWriter);
            HttpContext.Current.Response.Write(oStringWriter.ToString());
            HttpContext.Current.Response.End();
        }
         // 判断有没有相同的列，暂时只支持一列
         public   static   bool  CanImport( string  filename,  string  sheetName,  string  column)
        {
             string  strConn  =   " Provider=Microsoft.Jet.OLEDB.4.0;Data Source= "   +  filename  +   " ;Extended Properties=Excel 8.0; " ;
             if  (column  !=   "" )
            {
                 using  (OleDbConnection conn  =   new  OleDbConnection(strConn))
                {
                    OleDbDataAdapter oada  =   new  OleDbDataAdapter( string .Format( " select {0} from [{1}$] group by {0} having count({0})=2 " , column, sheetName), strConn);
                    DataTable dt  =   new  DataTable();
                    oada.Fill(dt);
                    conn.Close();
                     if  (dt.Rows.Count  >   0 ) {  return   false ; }
                }
            }
             return   true ;
        }
         // 将excel数据转换为DataTable
         public   static  DataTable ImportToTable( string  filename,  string  sheetName)
        {
            DataTable dt  =   new  DataTable();
             string  strConn  =   " Provider=Microsoft.Jet.OLEDB.4.0;Data Source= "   +  filename  +   " ;Extended Properties=Excel 8.0; " ;
             using  (OleDbConnection conn  =   new  OleDbConnection(strConn))
            {
                OleDbDataAdapter oada  =   new  OleDbDataAdapter( string .Format( " select * from [{0}$] " , sheetName), strConn);
                oada.Fill(dt);
            }
             return  dt;
        }
         // 从gridview导出Excel
         public   static   void  ExportFromGridview( string  fileName, GridView gv)
        {
             HttpContext.Current.Response.Clear();
             HttpContext.Current.Response.Charset  =   " utf-7 " ;
             HttpContext.Current.Response.ContentEncoding  =  System.Text.Encoding.GetEncoding( " utf-7 " ); // 设置输出流为简体中文
        HttpContext.Current.Response.AddHeader(
             " content-disposition " ,  string .Format( " attachment; filename={0}.xls " , fileName));
        HttpContext.Current.Response.ContentType  =   " application/ms-excel " ;

         using  (StringWriter sw  =   new  StringWriter())
        {
             using  (HtmlTextWriter htw  =   new  HtmlTextWriter(sw))
            {
                 //   Create a form to contain the grid
                Table table  =   new  Table();

                 //   add the header row to the table
                 if  (gv.HeaderRow  !=   null )
                {
                    PrepareControlForExport(gv.HeaderRow);
                    table.Rows.Add(gv.HeaderRow);
                }

                 //   add each of the data rows to the table
                 foreach  (GridViewRow row  in  gv.Rows)
                {
                    PrepareControlForExport(row);
                    table.Rows.Add(row);
                }

                 //   add the footer row to the table
                 if  (gv.FooterRow  !=   null )
                {
                    PrepareControlForExport(gv.FooterRow);
                    table.Rows.Add(gv.FooterRow);
                }

                 //   render the table into the htmlwriter
                table.RenderControl(htw);

                 //   render the htmlwriter into the response
                HttpContext.Current.Response.Write(sw.ToString());
                HttpContext.Current.Response.End();
            }
        }
        }
         // 处理gridview里面的特殊控件，如下拉列表或文本框等
         private   static   void  PrepareControlForExport(Control control)
        {
             for  ( int  i  =   0 ; i  <  control.Controls.Count; i ++ )
            {
                Control current  =  control.Controls[i];
                 if  (current  is  LinkButton)
                {
                    control.Controls.Remove(current);
                    control.Controls.AddAt(i,  new  LiteralControl((current  as  LinkButton).Text));
                }
                 else   if  (current  is  ImageButton)
                {
                    control.Controls.Remove(current);
                    control.Controls.AddAt(i,  new  LiteralControl((current  as  ImageButton).AlternateText));
                }
                 else   if  (current  is  HyperLink)
                {
                    control.Controls.Remove(current);
                    control.Controls.AddAt(i,  new  LiteralControl((current  as  HyperLink).Text));
                }
                 else   if  (current  is  DropDownList)
                {
                    control.Controls.Remove(current);
                    control.Controls.AddAt(i,  new  LiteralControl((current  as  DropDownList).SelectedItem.Text));
                }
                 else   if  (current  is  CheckBox)
                {
                    control.Controls.Remove(current);
                    control.Controls.AddAt(i,  new  LiteralControl((current  as  CheckBox).Checked  ?   " True "  :  " False " ));
                }

                 if  (current.HasControls())
                {
                    PrepareControlForExport(current);
                }
            }
        }
    }
}