验证码形成的部分在一个aspx文件中：
页面设置
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %> <!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></title> <style> #Image1 { cursor:pointer; } </style> </head> <body> <form id="form1" runat="server"> <div> 验证码：<asp:Image ID="Image1" runat="server" ImageUrl="tupian.aspx" /><%--ImageUrl指向一个Web窗口tupian.aspx 在该窗体中处理验证码--%> <asp:Label ID="Label1" runat="server" Text=""></asp:Label><br /><br /> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox><br /><%--输入验证码文本区--%> <asp:Button ID="Button1" runat="server" Text="登录" /> </div> </form> </body> </html> <script> var a = 0;//a的作用是使每次点击验证码图片都会变 document.getElementById("Image1").onclick = function () {//js更改属性，如果更改后的属性和以前的属性一样，不变 this.setAttribute("src", "tupian.aspx?id=" + a); a++; }; </script>
页面功能代码
using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class Default2 : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Button1.Click += Button1_Click; } void Button1_Click(object sender, EventArgs e) { if (TextBox1.Text.Trim().ToUpper() == Session["yzm"].ToString().ToUpper()) { Label1.Text = "正确"; } else { Label1.Text = "错误"; } } }
tupian.aspx代码页面（重点）
using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Drawing; public partial class tupian : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { //创建图片。位图 Bitmap bmap = new Bitmap(120,50);//宽：100px ；高：50px //绘制画布 Graphics g = Graphics.FromImage(bmap); Random r = new Random(); //创建颜色集合 List<Color> clist = new List<Color>(); clist.Add(Color.Peru); clist.Add(Color.Purple); clist.Add(Color.Pink); clist.Add(Color.PaleVioletRed); //绘制水印照片背景 g.FillRectangle(new SolidBrush(clist[r.Next(0,clist.Count)]),0,0,120,50); for (int h = 0; h < 6; h++)//位置不同，可以设置干扰线覆盖文字，还是文字覆盖干扰线 { //绘制干扰线 Pen p = new Pen(new SolidBrush(clist[r.Next(0, clist.Count)]), r.Next(0, 8)); g.DrawLine(p, r.Next(0, 120), r.Next(0, 50), r.Next(0, 120), r.Next(0, 50)); } //绘制验证码文字 string s = ""; string ss = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"; for (int i = 0; i < 4; i++) { s += ss.Substring(r.Next(0,ss.Length),1); } Session["yzm"] = s;//传验证码的值 //绘制文字格式和大小 Font f = new Font("宋体",30); //绘制画笔颜色，即文字颜色 Brush b = new SolidBrush(System.Drawing.Color.Red); //绘制水印 g.DrawString(s,f,b,1,5); //将水印照片存在”流“中，并且设定照片格式后缀 bmap.Save(Response.OutputStream,System.Drawing.Imaging.ImageFormat.Jpeg); //停止输出 Response.End(); } }
完！！