/// <summary> 
         /// 把DataTable内容导出伟excel并返回客户端 
         /// </summary> 
         /// <param name="dgData">待导出的DataTable</param> 
      
         public static void DataTable2Excel(System.Data.DataTable dtData) 
        { 
            System.Web.UI.WebControls.DataGrid dgExport = null; 
            // 当前对话 
            System.Web.HttpContext curContext = System.Web.HttpContext.Current; 
           // IO用于导出并返回excel文件 
            System.IO.StringWriter strWriter = null; 
            System.Web.UI.HtmlTextWriter htmlWriter = null; 

           if (dtData != null) 
           { 
                // 设置编码和附件格式               curContext.Response.ContentType = "application/vnd.ms-excel"; 
               curContext.Response.ContentEncoding =System.Text.Encoding.Default; 
               curContext.Response.Charset = ""; 
                
                // 导出excel文件 
                strWriter = new System.IO.StringWriter(); 
                htmlWriter = new System.Web.UI.HtmlTextWriter(strWriter); 
 
                // 为了解决dgData中可能进行了分页的情况，需要重新定义一个无分页的DataGrid 
                dgExport = new System.Web.UI.WebControls.DataGrid(); 
                dgExport.DataSource = dtData.DefaultView; 
                dgExport.AllowPaging = false; 
                dgExport.DataBind(); 
                 // 返回客户端 
                dgExport.RenderControl(htmlWriter);     
                curContext.Response.Write(strWriter.ToString()); 
                curContext.Response.End(); 
             

            } 


        }

         /// <summary> 
         /// 将DataTable数据导出到EXCEL，调用该方法后自动返回可下载的文件流 
         /// </summary> 
         /// <param name="dtData">要导出的数据源</param> 
         public static void DataTable1Excel(System.Data.DataTable dtData)
         {
             System.Web.UI.WebControls.GridView gvExport = null;
             // 当前对话 
             System.Web.HttpContext curContext = System.Web.HttpContext.Current;
             // IO用于导出并返回excel文件 
             System.IO.StringWriter strWriter = null;
             System.Web.UI.HtmlTextWriter htmlWriter = null;

             if (dtData != null)
             {
                 // 设置编码和附件格式 
                 curContext.Response.ContentType = "application/vnd.ms-excel";
                 curContext.Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");
                 curContext.Response.Charset = "utf-8";

                 // 导出excel文件 
                 strWriter = new System.IO.StringWriter();
                 htmlWriter = new System.Web.UI.HtmlTextWriter(strWriter);
                 // 为了解决gvData中可能进行了分页的情况，需要重新定义一个无分页的GridView 
                 gvExport = new System.Web.UI.WebControls.GridView();
                 gvExport.DataSource = dtData.DefaultView;
                 gvExport.AllowPaging = false;
                 gvExport.DataBind();

                 // 返回客户端 
                 gvExport.RenderControl(htmlWriter);
                 curContext.Response.Write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=gb2312\" />" + strWriter.ToString());
                 curContext.Response.End();
             }
         }




         /// <summary>
         /// 直接输出Excel
         /// </summary>
         /// <param name="dtData"></param>
         public static void DataTable3Excel(System.Data.DataTable dtData)
         {
             System.Web.UI.WebControls.DataGrid dgExport = null;
             // 当前对话
             System.Web.HttpContext curContext = System.Web.HttpContext.Current;
             // IO用于导出并返回excel文件
             System.IO.StringWriter strWriter = null;
             System.Web.UI.HtmlTextWriter htmlWriter = null;

             if (dtData != null)
             {
                 // 设置编码和附件格式
                 curContext.Response.ContentType = "application/vnd.ms-excel";
                 curContext.Response.ContentEncoding = System.Text.Encoding.Default;
                 curContext.Response.Charset = "";

                 // 导出excel文件
                 strWriter = new System.IO.StringWriter();
                 htmlWriter = new System.Web.UI.HtmlTextWriter(strWriter);

                 // 为了解决dgData中可能进行了分页的情况，需要重新定义一个无分页的DataGrid
                 dgExport = new System.Web.UI.WebControls.DataGrid();
                 dgExport.DataSource = dtData.DefaultView;
                 dgExport.AllowPaging = false;
                 dgExport.DataBind();

                 // 返回客户端
                 dgExport.RenderControl(htmlWriter);
                 curContext.Response.Write(strWriter.ToString());
                 curContext.Response.End();
             }
         }