个人学习代码保存:例12.读取GridView文件中的数据到Excel文件

前台代码：Default.aspx

<% @ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" EnableEventValidation = "false"  %>

<!-- EnableEventValidation = "false"  用GridView导出Execl的时候，会发生只能在执行 Render() 的过程中调用 RegisterForEventValidation的错误提示。  -->






<! DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >

< html  xmlns ="http://www.w3.org/1999/xhtml"   >
< head  runat ="server" >
     < title > 无标题页 </ title >
</ head >
< body >
     < form  id ="form1"  runat ="server" >
     < div >
         < asp:GridView  ID ="GridView1"  runat ="server" >
         </ asp:GridView >
    
     </ div >
         < asp:Button  ID ="Button1"  runat ="server"  OnClick ="Button1_Click"  Text ="导出Excel"   />
     </ form >
</ body >
</ html >

后台代码：Default.aspx.cs

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.SqlClient;






public   partial   class  _Default : System.Web.UI.Page 
{
    private static string connstr=ConfigurationManager.AppSettings["ConnectionString"].ToString();
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            this.GridView1.DataSource = GetData();
            this.GridView1.DataBind();
        }

    }

    public DataSet GetData()
    {
        SqlConnection con = new SqlConnection(connstr);
        if (con.State.Equals(ConnectionState.Closed))
        {
            con.Open();
        }
        string sql = "select *  from guestbook";
        SqlCommand cmd = new SqlCommand(sql,con);
        SqlDataAdapter sda = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        sda.Fill(ds);
        con.Close();
        return ds;
 
    }

    // 否则会出现:类型“GridView”的控件“GridView1”必须放在具有 runat=server 的窗体标记内。

    public override void VerifyRenderingInServerForm(Control control)
    {
        // Confirms that an HtmlForm control is rendered for 

    } 

    protected void Button1_Click(object sender, EventArgs e)
    {
        
        ExportDataGrid("online/ms-excel", "ddd.xls");
    }

    private void ExportDataGrid(string FileType, string FileName)
    {
        Response.Clear();
        Response.Buffer = true;
        Response.Charset = "utf-7";
        Response.AppendHeader("Content-Disposition", "attachment;filename=FileFlow.xls");
        Response.ContentEncoding = System.Text.Encoding.GetEncoding("utf-7");
        Response.ContentType = "application/ms-excel";
        this.EnableViewState = false;
        System.IO.StringWriter oStringWriter = new System.IO.StringWriter();
        System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);
        this.GridView1.RenderControl(oHtmlTextWriter);
        Response.Write(oStringWriter.ToString());
        Response.End();
    }

    

   
}