大小写字符及数字混合验证码 - 没有人烟

VerifyCode.aspx.cs

private void Page_Load(object sender, System.EventArgs e)
        {
            // 在此处放置用户代码以初始化页面
            Response.Buffer = true;
            string checkCode = CreateRandomCode(6);
            Session["CheckCode"] = checkCode;
            Session.Timeout = 1;
            CreateImage(checkCode);
        }

        Web 窗体设计器生成的代码#region Web 窗体设计器生成的代码
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
            //
            InitializeComponent();
            base.OnInit(e);
        }
        
        /**//// <summary>
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
        /// 此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {    
            this.Load += new System.EventHandler(this.Page_Load);

        }
        #endregion
        private string CreateRandomCode(int codeCount)
        {
            string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,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" ;
            string[] allCharArray = allChar.Split(\',\');
            string randomCode = "";
            int temp = -1;

            Random rand = new Random();
            for(int i = 0; i < codeCount; i++)
            {
                if(temp != -1)
                {
                    rand = new Random(i*temp*((int)DateTime.Now.Ticks));
                }
                int t = rand.Next(61);
                if(temp == t)
                {
                    return CreateRandomCode(codeCount);
                }
                temp = t;
                randomCode += allCharArray[t];
            }
            return randomCode;
        }

        private void CreateImage(string checkCode)
        {
            Response.Expires = -1;
            Response.AddHeader ("Pragma","no-cache");
            Response.AddHeader ("cache-ctrol","no-cache");
            int iwidth = (int)(checkCode.Length * 19);
            System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 35);
            Graphics g = Graphics.FromImage(image);
            Font f = new System.Drawing.Font("Arial", 18, System.Drawing.FontStyle.Regular);
            Brush b = new System.Drawing.SolidBrush(Color.RoyalBlue);
            //g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height);
            g.Clear(Color.AliceBlue);
            g.DrawString(checkCode, f, b, 5, 5);

            Pen blackPen = new Pen(Color.RoyalBlue, 0);
            Random rand = new Random();
            //随机产生的竖条
            for (int i=0;i<5;i++)
            {
                int x = rand.Next(image.Width);
                
                g.DrawLine(blackPen,x,0,x,image.Height);
                
            }
            
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            image.Save(ms,System.Drawing.Imaging.ImageFormat.Jpeg);
            Response.ClearContent();
            Response.ContentType = "image/Jpeg";
            Response.BinaryWrite(ms.ToArray());
            g.Dispose();
            image.Dispose();
        }

调用以及验证

验证码：<asp:TextBox id="VerifyCode" Width="50" runat="server"></asp:TextBox>
            <asp:Image id="VerifyCode2" ImageAlign="AbsMiddle" ImageUrl="VerifyCode.aspx" runat="server"></asp:Image>

private void Page_Load(object sender, System.EventArgs e)
        {
            // 在此处放置用户代码以初始化页面
            string checkCode; 
            if(Session["CheckCode"]!= null) 
            { 
                checkCode = Session["CheckCode"].ToString(); 
                Session.Abandon(); 
            }
            else
            {
                checkCode = "99999"; //验证码过期
            }
            ViewState["CheckCode"] = checkCode; 
        }

        Web 窗体设计器生成的代码#region Web 窗体设计器生成的代码
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
            //
            InitializeComponent();
            base.OnInit(e);
        }
        
        /**//// <summary>
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
        /// 此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {    
            this.btn_Reg.Click += new System.EventHandler(this.btn_Reg_Click);
            this.Load += new System.EventHandler(this.Page_Load);

        }
        #endregion

        private void btn_Reg_Click(object sender, System.EventArgs e)
        {
            
            if (VerifyCode.Text.Trim() != ViewState["CheckCode"].ToString())
            {
                if (ViewState["CheckCode"].ToString() == "99999")
                {
                    Response.Write("<script>alert(\"由于您放置时间过长,验证码失效!请刷新后输入!\");location=\'Login.aspx\'</script>");
                }
                else
                {
                    Response.Write("<script>alert(\"您输入的验证码不正确!请重新输入!\");location=\'Login.aspx\'</script>");
                }
            }
            else
            {
                .......                    
                }
                                
            }
            
        }