ASP.NET登录时验证码的制作与验证
ASP.NET 验证码的制作与校验(使用 cookie 传值)
(1)验证码应该是图片格式,不能是文字格式,即无法用鼠标选中。 (2)验证码上应该有噪点和干扰线条。 (3)验证码应该回避相似字符,如“0”和“o”“I”和“1”等。 (4)验证码至少是数字和字母(含大小写)的组合,不应该是单纯的数字或字母,可以出现汉字。应该实现输入验证码字母字母“不区分大小写”。验证码中的内容,应该是随机生成。 (5)验证码,可以通过点击图片或旁边文字实现“看不清,换一张”的功能。 (6)应当有个用于核对验证码输入是否正确的tbx和btn,当点击btn时,弹窗提示验证码输入的是正确或错误。
一、效果
制作验证码主要是利用了C#的GDI绘制,效果如下图所示:
二、代码实现
项目资源分布
主页 WebForm1.aspx
<!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></head><body> <form id="form1" runat="server"> <div> <asp:Label ID="Label1" runat="server" Text="验证码:" Font-Size="25px"></asp:Label> <asp:TextBox ID="tbx_imgcheckingcode" runat="server" Width="82px" Height="25px"></asp:TextBox> <asp:ImageButton ID="ibtn_imgcheckingcode" src="WebForm2.aspx" runat="server" Height="40px" Width="70px" οnclick="this.src=this.src+'?'" ToolTip="看不清我,就点一下我吧!" /> <a href="javascript:changeCode()" style="text-decoration: underline; font-size: 10px;">换一张</a><br /> <script type="text/javascript"> function changeCode() { document.getElementById('ibtn_imgcheckingcode').src = document.getElementById('ibtn_imgcheckingcode').src + '?'; } </script> <asp:Button ID="Button1" runat="server" Text="验证" OnClick="Button1_Click" /> </div> </form></body></html>
WebForm1.aspx.cs(注意 namespace 的引用,改成自己的项目名)
using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;namespace ImageCode{ public partial class WebForm1 : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { //引入验证码 url ibtn_imgcheckingcode.ImageUrl = "WebForm2.aspx"; } //使用cookie传值验证 protected void Button1_Click(object sender, EventArgs e) { string checkingcode = tbx_imgcheckingcode.Text; //收到cookie请求的对象 HttpCookie cookie_checkingcode = Request.Cookies["ImageV"]; //将验证码中的字母转为大写,进行校验 string scode = cookie_checkingcode.Value.ToUpper().ToString(); if (checkingcode.ToUpper()!= scode) { Response.Write("alert('验证码输入不正确!')"); } else { this.tbx_imgcheckingcode.Text = ""; Response.Write("alert('验证码输入正确')"); } } }}
验证码页面 WebForm2.aspx (什么都不用写)
<!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></head><body> <form id="form1" runat="server"> <div> </div> </form></body></html>
WebForm2.aspx.cs
注意using
引用
using System;using System.Collections.Generic;//引入画板using System.Drawing;using System.Drawing.Imaging;using System.IO;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;namespace ImageCode{ public partial class WebForm2 : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { string tmp = RndNum(4); //将验证码写入cookie HttpCookie a = new HttpCookie("ImageV", tmp); Response.Cookies.Add(a); this.ValidateCode(tmp); } private void ValidateCode(string VNum) {//创建位图对象 Bitmap Img = null; Graphics g = null //分配内存空间 MemoryStream ms = null; int gheight = VNum.Length * 12; Img = new Bitmap(gheight, 25); g = Graphics.FromImage(Img); //生成随机生成器 Random random = new Random(); //背景颜色 g.Clear(Color.White); //生成噪点随机颜色 for (int i = 0; i < 100; i++) { int x = random.Next(Img.Width); int y = random.Next(Img.Height); Img.SetPixel(x, y, Color.FromArgb(random.Next())); } //添加干扰线条 int z =6;//干扰线条数 for (int i = 0; i < z; i++) { int x1 = random.Next(Img.Width); int x2 = random.Next(Img.Width); int y1 = random.Next(Img.Height); int y2 = random.Next(Img.Height); //随机干扰线条颜色 int r = random.Next(255); int green = random.Next(255); int b = random.Next(255); g.DrawLine(new Pen(Color.FromArgb(r,green,b), 1), x1, y1, x2, y2);//根据坐标画线 } //文字字体 Font f = new Font("Arial Black ", 12); //文字颜色 SolidBrush s = new SolidBrush(Color.Blue); //画验证码 g.DrawString(VNum, f, s, 3, 3); ms = new MemoryStream(); //将验证码图片存入内存流,并将其以 "image/Jpeg" 格式输出 Img.Save(ms, ImageFormat.Jpeg); Response.ClearContent(); Response.ContentType = "image/Jpeg "; Response.BinaryWrite(ms.ToArray()); //显式释放资源 g.Dispose(); Img.Dispose(); Response.End(); } private string RndNum(int VcodeNum) { // //定义存放的字符串回避相似字符 string Vchar = "2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,J,K,M,N,P" + ",Q,R,S,T,U,V,W,X,Y,Z,a,b,c,d,e,f,g,h,g,k,m,n,p,q,r,s,t,u,v,w,x,y,z"; string[] VcArray = Vchar.Split(new Char[] { ',' }); string VNum = " "; int temp = -1; Random rand = new Random(); for (int i = 1; i < VcodeNum + 1; i++) { if (temp != -1) { rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks)); } int t = rand.Next(54); if (temp != -1 && temp == t) { return RndNum(VcodeNum); } temp = t; VNum += VcArray[t]; } return VNum; } }}