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The author:(作者)delvpublished in(发表于) 2014/1/24 9:10:16 Login控件也可添加图文验证码_[Asp.Net教程]
对asp.net提供的Login控件进行扩展,在密码后面加一图文验证功能以防止自动注册程序。1.添加imageValidate.aspx,在头部添加信息<% Response.Buffer = true ;%><% Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-1);%><% Response.Expires = 0 ;%><% Response.CacheControl = "no-cache" ; %>在imageValidate.aspx.cs中的代码如下:protected void Page_Load(object sender, EventArgs e) { //生成4位的验证码 /*string tmp = RndNum(4); HttpCookie cookie = new HttpCookie("ImageV", tmp); //Response.Cookies["ImageV"].Value=tmp; Response.Cookies.Add(cookie); this.ValidateCode(tmp);*/ CreateCheckCodeImage(GenerateCheckCode()); } private string GenerateCheckCode() { int number; char code; string checkCode = String.Empty; System.Random random = new Random(); for (int i = 0; i < 5; i++) { number = random.Next(); if (number % 2 == 0) code = (char)('0' + (char)(number % 10)); else code = (char)('A' + (char)(number % 26)); checkCode += code.ToString(); } Session["CheckCode"] = checkCode; //Response.Cookies.Add(new HttpCookie("CheckCode", checkCode)); return checkCode; } private void CreateCheckCodeImage(string checkCode) { if (checkCode == null || checkCode.Trim() == String.Empty) return; System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 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 for (int 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.FontStyle.Italic)); 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 for (int i = 0; i < 100; i++) { int x = random.Next(image.Width); int y = random.Next(image.Height); image.SetPixel(x, y, Color.FromArgb(random.Next())); } //画图片的边框线 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); Response.ClearContent(); Response.ContentType = "image/Gif"; Response.BinaryWrite(ms.ToArray()); } finally { g.Dispose(); image.Dispose(); } }这就是生成验证码的页面2.将这页面添加到login控件中:拖曳一Login控件,将之切换到模式下,在Html源文件中在表格中密码那行后添加: 验证码: 其中ImageUrl="~/public/imageValidate.aspx“ 的imageValidate.aspx指的就是我们第一步建立的文件。3.在login控件的authenticate事件中加入代码protected void Login1_Authenticate(object sender, AuthenticateEventArgs e) { TextBox txtImage = Login1.FindControl("txtImgValid") as TextBox; if (Session["CheckCode"] == null) { Response.Write(""); e.Authenticated = false; return; } if (String.Compare(Session["CheckCode"] .ToString(),txtImage.Text,true)!=0) { Response.Write(""); e.Authenticated = false; return; } e.Authenticated = true; }单击登录按钮后顺便将session清空protected void LoginButton_Click(object sender, EventArgs e) { Session["CheckCode"] = null; }运行结果如图:来源:网络
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