解决|问题|验证码
在网上找了一个验证码的源代码，使用后出现如下问题：不管你输入正确与否，都会提示验证码错误。后来经过在qq群里和csdn发贴咨询，得知是ie浏览器缓存问题。在经过他人的指点后改正了错误。源代码如下：
-------------------Validate.aspx------------------
<% Page Language="C#" %>
<% import namespace="System"%>
<% import namespace="System.IO"%>
<% import namespace="System.Drawing"%>
<% import namespace="System.Drawing.Imaging"%>
<% import namespace="System.Drawing.Drawing2D"%>
<script runat="server">
private Bitmap validateimage;
private Graphics g;
public void Page_Load(object Sender ,EventArgs e ){
Response.BufferOutput = true; //特别注意
Response.Cache.SetExpires(DateTime.Now.AddMilliseconds(-1));//特别注意
Response.Cache.SetCacheability(HttpCacheability.NoCache);//特别注意
Response.AppendHeader("Pragma", "No-Cache"); //特别注意
string VNum =MakeValidateCode( );
Session["VNum"]=VNum;//取得验证码，以便后来验证
ValidateCode(VNum);}
public void ValidateCode(string VNum)
{
validateimage = new Bitmap(60, 20, PixelFormat.Format24bppRgb);
g = Graphics.FromImage(validateimage);
g.FillRectangle(new LinearGradientBrush(new Point(0,0), new Point(110,20), Color.FromArgb(240,255,255,255),Color.FromArgb(240,255,255,255)),0,0,200,200);
g.DrawString(VNum, new Font("arial",11),new SolidBrush(Color.Red),new PointF(6,0));
g.Save();
MemoryStream ms=new MemoryStream();
validateimage.Save(ms,System.Drawing.Imaging.ImageFormat.Gif);
Response.ClearContent();
Response.ContentType="image/bmp";
Response.BinaryWrite(ms.ToArray());
Response.End();
}
string MakeValidateCode()
{
char[] s = new char[]{'0','1', '2','3','4','5','6','7','8','9','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
string num = "";
Random r = new Random();
for(int i = 0; i < 5; i++)
{
num += s[r.Next(0, s.Length)].ToString();
}
return num;
}
</script>
-----------------------register.aspx------------
<% Page Language="C#" AutoEventWireup="true" CodeFile="Register.aspx.cs" Inherits="MyRegister.Register" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">
<html xmlns="" >
<head runat="server">
<title>会员注册</title>
<LINK href="stylesheet.css" _fcksavedurl=""stylesheet.css"" _fcksavedurl=""stylesheet.css"" _fcksavedurl=""stylesheet.css"" type="text/css" rel="stylesheet">
</head>
<body>
<form id="form1" runat="server">
<div class="middle" 1px" >
<div >
<asp:Label ID="UserName" runat="server" Text="用户名：" ></asp:Label>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
</div>
<div >
<asp:Label ID="UserPsw" runat="server" Text="密码：" ></asp:Label>
<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox></div>
<div >
<asp:Label ID="Label2" runat="server" Text="确认密码：" ></asp:Label>
<asp:TextBox ID="TextBox6" runat="server"></asp:TextBox></div>
<div >
<asp:Label ID="Question" runat="server" Text="找回密码问题："></asp:Label>
<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox></div>
<div>
<asp:Label ID="Answer" runat="server" Text="找回密码答案："></asp:Label>
<asp:TextBox ID="TextBox4" runat="server"></asp:TextBox></div>
<div >
<asp:Label ID="Email" runat="server" Text="电子邮件："></asp:Label>
<asp:TextBox ID="TextBox5" runat="server"></asp:TextBox></div>
<div >
<asp:Label ID="Label1" runat="server" Text="验证码："></asp:Label>
<asp:TextBox ID="CheckCode" runat="server" Width="85px"></asp:TextBox>
<asp:Image id="Image1" runat="server" ImageUrl="Validate.aspx"></asp:Image></div>
<div>
<asp:Button ID="Button1" runat="server" Text="确定" /></div>
<div class="text">
<asp:Label ID="Message" runat="server" ></asp:Label></div>
</div>
</form>
</body>
</html>
-------------------------register.aspx.cs-------------------
using System;
using System.Data;
using System.Configuration;
using System.Collections;
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;
namespace MyRegister
{
public partial class Register : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
string checkcode = CheckCode.Text;
//Response.Write(Session["VNum"]);
if (checkcode == Session["VNum"].ToString() || Session["VNum"].ToString()==null)//注意Session["VNum"].ToString()，必须加上ToString()，因//为Session["VNum"]是对象。
Response.Redirect ("default.aspx");
else
Message.Text = "验证码错误或为空！";
}
}
}
---------------------------------
其中注释的地方应特别注意
