先照着网上找的代码做了一个Validcode.aspx.cs页，然后在另一个页面上拉了一个TEXTBOX控件，在后面加了一个 <iframe src="Validcode.aspx" height="25" width="100" scrolling="no" frameborder="0" marginwidth="0" marginheight="0" style="width: 60px; height: 22px"></iframe>
浏览时就可以显示出验证码来了
然后我在后台加代码
if (this.TextBox1.Text == Session["ValidCode"].ToString()) { Response.Write("验证成功！"); } else { Response.Write("验证失败！"); }出现错误：未将对象引用设置到对象的实例。
然后把代码去掉，又在页面上加了<IMG src="Validcode.aspx"/>
奇怪的事发生了，两张图片竟然显示不一样的验证码！！！到底要添哪一个？？？
我的前台页面
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="yzm.aspx.cs" Inherits="yzm" %><!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:TextBox ID="TextBox1" runat="server"></asp:TextBox> <iframe src="Validcode.aspx" height="25" width="100" scrolling="no" frameborder="0" marginwidth="0" marginheight="0" style="width: 60px; height: 22px"></iframe> <IMG src="Validcode.aspx"/> </div> </form></body></html>
Validcode.aspx.cs页
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;using System.Drawing;using System.Text;public partial class validcode : System.Web.UI.Page
{
private void Page_Load(object sender, System.EventArgs e)
{ this.CreateCheckCodeImage(GenerateCheckCode());
}
Web 窗体设计器生成的代码 private string GenerateCheckCode() { int number; char code; string checkCode = String.Empty; System.Random random = new Random(); for (int i = 0; i < 5; i++) { number = random.Next(); if (number % 2 == 0) code = (char)('0' + (char)(number % 10)); else code = (char)('A' + (char)(number % 26)); checkCode += code.ToString(); } //Response.Cookies.Add(new HttpCookie("CheckCode", checkCode)); Session["ValidCode"] = checkCode; return checkCode; } private void CreateCheckCodeImage(string checkCode) { if (checkCode == null || checkCode.Trim() == String.Empty) return; System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22); Graphics g = Graphics.FromImage(image); try { //生成随机生成器 Random random = new Random(); //清空图片背景色 g.Clear(Color.White); //画图片的背景噪音线 for (int i = 0; i < 25; i++) { int x1 = random.Next(image.Width); int x2 = random.Next(image.Width); int y1 = random.Next(image.Height); int y2 = random.Next(image.Height); g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2); } Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic)); System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true); g.DrawString(checkCode, font, brush, 2, 2); //画图片的前景噪音点 for (int i = 0; i < 100; i++) { int x = random.Next(image.Width); int y = random.Next(image.Height); image.SetPixel(x, y, Color.FromArgb(random.Next())); } //画图片的边框线 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1); System.IO.MemoryStream ms = new System.IO.MemoryStream(); image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); Response.ClearContent(); Response.ContentType = "image/Gif"; Response.BinaryWrite(ms.ToArray()); } finally { g.Dispose(); image.Dispose(); } }
}
