动态生成验证码

来源：互联网发布：淘宝平面模特怎么找编辑：程序博客网时间：2024/05/16 05:26

动态生成验证码在很多地方可以用到，最近在学习牛腩视频的时候，正好看到了，就此简单总结一下。

为了简单方便，我们新建一个验证码测试的项目名为test，然后在项目中新建一个文件夹，在这个文件夹中添加一个“一般处理程序”页，命名为WaterMark.ashx ，效果如下：

WaterMark.ashx中的代码如下所示：

<%@ WebHandler Language="C#" Class="WaterMark" %>using System;using System.Web;using System.Drawing;using System.Drawing.Drawing2D;using System.Web.SessionState;public class WaterMark : IHttpHandler, IRequiresSessionState  // 要使用session必须实现该接口,记得要导入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";        char[] chastr = str.ToCharArray();        string code = "";        Random rd = new Random();        int i;        for (i = 0; i < num; i++)        {            code += str.Substring(rd.Next(0, str.Length), 1);        }        return code;    }    public bool IsReusable    {        get        {            return false;        }    }}

在Default.aspx中代码如下：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %><!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml"><head runat="server"><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>    <title>验证码实验</title>    <script lang ="javascript" type ="text/javascript" >        function changeCode() {            var imgNode = document.getElementById("vimg");            imgNode.src = "handler/WaterMark.ashx?t=" + (new Date()).valueOf();        }    </script>    </head><body>    <form id="form1" runat="server">    <div>        <%--<p>验证码1：<img src="handler/WaterMark.ashx" id="vimg" alt="" onclick="changeCode()" /></p>--%>        <p>验证码2：<asp:Image ID="vimg" runat="server" ImageUrl ="handler/WaterMark.ashx" onclick="changeCode()" /></p>    </div>    </form></body></html>

当验证输入的验证码与当前验证码是否一致时，代码如下：

        string code = txtCode.Text.Trim().ToUpper();  //用户输入的验证码        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>");            txtCode.Text = "";            return;        }

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