c#验证码实现~

验证码页面的前台代码默认即可不用管它，只需要要将其后台代码改为如下即可。 验证码生成文件：validate.aspx.cs using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using System.IO; using System.Drawing; using System.Drawing.Imaging; using System.Drawing.Drawing2D; public partial class validate : System.Web.UI.Page private Bitmap validateimage; private Graphics g; protected void Page_Load(object sender, EventArgs e) if (!IsPostBack) string VNum = MakeValidateCode(); Session“VNum“ = VNum; ValidateCode(VNum); public void ValidateCode(string VNum) validateimage = new Bitmap(42, 15, PixelFormat.Format24bppRgb); /生成图片的长和高 g = Graphics.FromImage(validateimage); g.FillRectangle(new LinearGradientBrush(new Point(0, 0), new Point(110, 20), Color.FromArgb(240, 255, 255, 255), Color.FromArgb(240, 255, 255, 255), 0, 0, 200, 200); g.DrawString(VNum, new Font(“arial“, 9), new SolidBrush(Color.Red), new PointF(1, 0); /上面的一句用来设定：验证码的字体大小、颜色、图片字前面空的格数 g.Save(); MemoryStream ms = new MemoryStream(); validateimage.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); Response.ClearContent(); Response.ContentType = “image/bmp“; Response.BinaryWrite(ms.ToArray(); Response.End(); string MakeValidateCode() char s = new char 2,3,4,5,6,7,8,9, a,b,c,d,e,f,g,h,i,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z, 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 ; /剔除了部分难以辨别的字符，还可加入汉字等字符 string num = “; Random r = new Random(); for (int i = 0; i 之间就 可以了） 注意：有一点要说明，当点击刷新时，validate.asp?后面一定要有一个参数，若没有这个无效 的参数，程序会认为你请求的是同一个文件，因而不会刷新的。这里的参数 abc是个随意的，只 起改变请求文件的作用。 以下为校验验证码是否输入正确的语句，放在Login.aspx.cs文件中 protected void Button1_Click(object sender, EventArgs e) string Time = DateTime.Now.ToString(); string ip = Request.UserHostAddress.ToString(); Sqlselete ss = new Sqlselete(); SqlInsert sl = new SqlInsert(); string text = this.TextBox1.Text.ToString();/获得用户输入的验证码 string chkcode = Session“validate“.ToString(); /获取系统生成的验证码 if (username.Text.Trim() = “) Response.Write(“alert(请输入帐号!); window.location.href=Login.aspx“); if (password.Text.Trim() = “) Response.Write(“alert(请输入密码!); window.location.href=Login.aspx“); if (string.IsNullOrEmpty(text) Response.Write(“alert(请输入验证码!); window.location.href=Login.aspx“); else if (chkcode != chkcode.ToUpper() /如果系统生成的不为大写则转换成大写形式 chkcode = chkcode.ToUpper(); if (text.ToUpper().Trim() = (chkcode.Trim() /将输入的验证码转换成大写并与系 统生成的比较 string UserName = this.username.Text.Trim(); string Password = password.Text.Trim(); if (ss.Login(UserName, Password) = false) /对账户密码进行验证 string State = “登录失败“; Response.Write(“alert(帐号或密码错误！)“); else Response.Write(“alert(登录成功！)“); Session“UserName“ = UserName; /记录用户名，可在其它模块中使用 用法： aaa = Session“UserName“.ToString() /以下的这几语句就是登入之后的操作了 string tt = “ qminoa = window.open(Default.aspx“ + “ + “,toolbar=no,menubar=no,titlebar=yes,directories=no,resizable=yes,status=yes,fullscreen =no,top=0;left=0,width=900,height=700);“; Response.Write(“); Response.Write(tt); Response.Write(“qminoa.moveTo(0,0);“); Response.Write(“qminoa.resizeTo(screen.availWidth,screen.availHeight);“); R