ASP.NET验证码实现-优快云博客

前台：

<asp:TextBox ID="TextBox5" runat="server"></asp:TextBox>
                                <img src="YanZheng.aspx" onclick="this.src='YanZheng.aspx?aaa='+new Date()" alt="" /><span
                                    style="color: Red; font-size: small;">图片看不清？点击重新得到验证码</span>
                                <asp:RequiredFieldValidator ID="RequiredFieldValidator5" runat="server" ControlToValidate="TextBox5"
                                    Display="Dynamic" ErrorMessage="不能为空"></asp:RequiredFieldValidator>

后台：

放到click事件中就行

if (Session["CheckCode"] == null)
                {
                    this.lbinfo.Text = "验证码生成错误";
                }
                else
                {
                    if (TextBox5.Text.ToUpper().Equals(Session["CheckCode"] + ""))
                    {
                        if (CheckBox1.Checked)
                        {
                            int number;
                            优快云Blogs.BLL.T_Users count = new BLL.T_Users();
                            number = count.GetRecordCount("U_Email=" + "'" + txtEmail.Text + "'");
                          else
                            {
                                优快云Blogs.Model.T_Users user = new 优快云Blogs.Model.T_Users();
                                user.U_Name = txtName.Text;
                                user.U_Email = txtEmail.Text;
                                user.U_Password = txtPassword.Text;
                                string activecode = Guid.NewGuid().ToString().Substring(0, 8);
                                user.ActiveCode = activecode;//生成激活码
                                优快云Blogs.BLL.T_Users buser = new 优快云Blogs.BLL.T_Users();
                                if (buser.Add(user) > 0)
                                {
                                    sendMail(txtEmail.Text, activecode);//给注册用户发邮件
                                    lbinfo.Text = "保存成功，请到邮箱激活！";
                                }
                                else
                                {
                                    lbinfo.Text = "很抱歉，保存失败！";
                                }
                            }
                        }
                                            }
                    else
                    {
                        this.lbinfo.Text = "验证码输入错误，请重新输入！";
                    }
                }

验证页：前台：

后台：

protected void Page_Load(object sender, EventArgs e)
        {
            CreateCheckCodeImage(GenerateCheckCode());//调用下面两个方法;
        }
        /// <summary>
        /// 生成验证码的随机数
        /// </summary>
        /// <returns>返回五位随机数</returns>
        private string GenerateCheckCode()
        {
            int number;
            char code;
            string checkCode = String.Empty;

Random random = new Random();

            for (int i = 0; i < 5; i++)//可以任意设定生成验证码的位数
            {
                number = random.Next();

                if (number % 2 == 0)
                    code = (char)('0' + (char)(number % 10));
                else
                    code = (char)('A' + (char)(number % 26));

checkCode += code.ToString();
}

            Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));//写入COOKIS
            Session["CheckCode"] = checkCode; //写入Session，可以任意选一下
            return checkCode;
        }

        /// <summary>
        /// 生成验证码图片
        /// </summary>
        /// <param name="checkCode"></param>
        private void CreateCheckCodeImage(string checkCode)
        {
            if (checkCode == null || checkCode.Trim() == String.Empty)
                return;

Bitmap image = new 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));
                LinearGradientBrush brush = new 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);

                MemoryStream ms = new MemoryStream();
                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                Response.ClearContent();
                Response.ContentType = "image/Gif";
                Response.BinaryWrite(ms.ToArray());
            }
            finally
            {//释放对象资源
                g.Dispose();
                image.Dispose();
            }
        }

验证码的验证