解析验证码
自己以前对验证码就很好奇，感觉它可以随机生成，很神奇，最近在看牛腩视频的时候，正好学到了验证码的时候，自己也做了一些整理，也好好的感悟了一下里面的原理。
后台登录界面
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="adminLogin.aspx.cs" Inherits="Web.admin.adminLogin" %>
<!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>后台登录-牛腩新闻发布系统</title>
<link href="../css/cssLogin.css" rel="stylesheet" type="text/css" />
<script language="javascript" type="text/javascript">
function changeCode() {
var imgNode = document.getElementById("vimg");
imgNode.src = "../handler/WaterMark.ashx?t=" + (new Date()).valueOf(); //这里价格时间的参数是为了防止浏览器缓存的问题
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div id="loginfrm" class="round1">
<h3>后台登录——牛腩新闻发布系统</h3>
<div id="login">
<img src="../image/niunanlogo.jpg" alt="牛腩logo" class="login_logo" />
<p>用户名：<asp:TextBox ID="txtUserName" runat="server" CssClass="textbox"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ErrorMessage="请输入用户名！" Text="*" ControlToValidate="txtUserName"></asp:RequiredFieldValidator>
</p>
<p>密 码：<asp:TextBox ID="txtPassword" runat="server" TextMode="Password" CssClass="textbox"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ErrorMessage="请输入密码！" Text="*" ControlToValidate="txtPassword"></asp:RequiredFieldValidator>
</p>
<p>验证码：<img src="../handler/WaterMark.ashx" id="vimg" alt="" onclick="changeCode()" />
<asp:TextBox ID="txtCode" runat="server" CssClass="textcode"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server" ErrorMessage="请输入验证码！" Text="*" ControlToValidate="txtCode"></asp:RequiredFieldValidator>
</p>
<p><asp:Button ID="btnLogin" runat="server" Text="登录" onclick="btnLogin_Click" /></p>
<asp:ValidationSummary ID="ValidationSummary1" runat="server" ShowMessageBox="true" ShowSummary="false" />
</div>
<div id="footer">版权所有 © <a href="http://niunan.javaeye.com">牛腩</a>&<a href="http://www.tg029.com"target="_blank">众志网</a></div>
</div>
</form>
</body>
</html>
C#代码
<SPAN style="FONT-SIZE: 18px">using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using BLL;
using System.Web.Security;
namespace Web.admin
{
public partial class adminLogin : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
//登录按钮
protected void btnLogin_Click(object sender, EventArgs e)
{
//判断验证码是否输入正确
string code = txtCode.Text.Trim().ToUpper();
string rightCode = Session["Code"].ToString();
if (code != rightCode)
{
Page.ClientScript.RegisterStartupScript(Page.GetType(), "message", "<script language='javascript' defer>alert('验证码输入错误！');</script>");
return;
}
string name = txtUserName.Text.Trim();
string pwd = txtPassword.Text.Trim();
//把密码转为Md5码的形式
pwd = FormsAuthentication.HashPasswordForStoringInConfigFile(pwd, "MD5");
bool b = LoginManager.Login(name,pwd);
//判断登录是否成功
if (b)
{
//登录成功
Session["admin"] = name;
Response.Redirect("Categorymanager.aspx");
}
else
{
Page.ClientScript.RegisterStartupScript(Page.GetType(), "message", "<script language='javascript' defer>alert('登录失败，请联系管理员！');</script>");
}
}
}
}</SPAN>
一般处理程序WaterMark.ashx的代码
<SPAN style="FONT-SIZE: 18px">using System;
using System.Web;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Web.SessionState;
namespace Web.handler
{
/// <summary>
/// WaterMark 的摘要说明
/// </summary>
public class WaterMark : IHttpHandler, IRequiresSessionState // 要使用session必须实现该接口,导入System.Web.SessionState命名空间
{
public void ProcessRequest(HttpContext context)
{
string checkCode = GenCode(5); // 产生5位随机字符
context.Session["Code"] = checkCode; //将字符串保存到Session中，以便需要时进行验证
System.Drawing.Bitmap image = new System.Drawing.Bitmap(70, 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
int i;
for (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.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
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);
context.Response.ClearContent();
context.Response.ContentType = "image/Gif";
context.Response.BinaryWrite(ms.ToArray());
}
finally
{
g.Dispose();
image.Dispose();
}
}
/// <summary>
/// 产生随机字符串
/// </summary>
/// <param name="num">随机出几个字符</param>
/// <returns>随机出的字符串</returns>
private string GenCode(int num)
{
string str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//"的一是在不了有和人这中大为上个国我以要他时来用们生到作地于出就分对成会可主发年动同工也能下过子说产种面而方后多定行学法所民得经十三之进着等部度家电力里如水化高自二理起小物现实加量都两体制机当使点从业本去把性好应开它合还因由其些然前外天政四日那社义事平形相全表间样与关各重新线内数正心反你明看原又么利比或但质气第向道命此变条只没结解问意建月公无系军很情者最立代想已通并提直题党程展五果料象员革位入常文总次品式活设及管特件长求老头基资边流路级少图山统接知较将组见计别她手角期根论运农指几九区强放决西被干做必战先回则任取据处队南给色光门即保治北造百规热领七海口东导器压志世金增争济阶油思术极交受联什认六共权收证改清己美再采转更单风切打白教速花带安场身车例真务具万每目至达走积示议声报斗完类八离华名确才科张信马节话米整空元况今集温传土许步群广石记需段研界拉林律叫且究观越织装影算低持音众书布复容儿须际商非验连断深难近矿千周委素技备半办青省列习响约支般史感劳便团往酸历市克何除消构府称太准精值号率族维划选标写存候毛亲快效斯院查江型眼王按格养易置派层片始却专状育厂京识适属圆包火住调满县局照参红细引听该铁价严";
char[] chastr = str.ToCharArray();
// string[] source ={ "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 code = "";
Random rd = new Random();
int i;
for (i = 0; i < num; i++)
{
//code += source[rd.Next(0, source.Length)];
code += str.Substring(rd.Next(0, str.Length), 1);
}
return code;
}
public bool IsReusable
{
get
{
return false;
}
}
}
}</SPAN>