asp.net使用ashx生成图形验证码

来源：互联网发布：淘宝有没有岛国动作片编辑：程序博客网时间：2024/06/07 15:37

验证码的好处不用我多说，你们都懂的。我在网上看到有人把验证码直接写在aspx页面里，也就是说这种方式请求验证码等于请求一个页面，这样做很不科学。如下所示

 <form id="form1" runat="server">    <div>            <asp:Image ID="Image1" runat="server" ImageUrl="Default.aspx" />            <br />        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>        <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />        </div>    </form>

这个代码看着就觉得写代码的人比较欠揍，代码写成这样子着实郁闷。验证吗也不写点script做下切换。

下面我介绍一种方式来实现这样的功能

1.写个ashx生成图形验证码

using System;using System.Collections;using System.Data;using System.Linq;using System.Web;using System.Web.Services;using System.Web.Services.Protocols;using System.Xml.Linq;using System.Web.SessionState;using System.Drawing;namespace usechecknum.ashx{    /// <summary>    /// $codebehindclassname$ 的摘要说明    /// </summary>    [WebService(Namespace = "http://tempuri.org/")]    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]    public class doCreateNum : IHttpHandler,IRequiresSessionState    {        public void ProcessRequest(HttpContext context)        {            context.Response.ContentType = "text/html";            string checkCode = GetValidation(5);  // 产生5位随机验证码字符            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();            }        }        public string GetValidation(int num)        {            string str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; //"或者写汉字也行"            string validatecode = "";            Random rd = new Random();            for (int i = 0; i < num; i++)            {                validatecode += str.Substring(rd.Next(0, str.Length), 1);            }            return validatecode;                   }        public bool IsReusable        {            get            {                return false;            }        }    }}

2.在页面上显示验证码，因为我们生成的是图形，所以可以直接写在<img/>标签里，我们只要写段简单的脚本就可以点击鼠标切换验证码了

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="index.aspx.cs" Inherits="usechecknum._Default" %><!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>验证码的使用</title></head><script language="javascript" type="text/javascript">    function changeCode() {           var imgNode = document.getElementById("vimg");           imgNode.src = "ashx/doCreateNum.ashx?t=" + (new Date()).valueOf();  // 这里加个时间的参数是为了防止浏览器缓存的问题       }    </script><body>    <form id="form1" runat="server">     请输入验证码:<input type="text" name="checknum"/><img src="ashx/doCreateNum.ashx"  id="vimg" onclick="changeCode()" />    </form></body></html>

说了半天，该是时候看看生成的验证码长什么样了