.net JS调用之验证码的实现

//前台‘验证码’代码<td height="20" align="left" > <asp:TextBox ID="txtYanzheng" runat="server" Width="80px"></asp:TextBox> <img alt="刷新" onclick="this.src='Image.aspx?id=' + Math.random() * 10000" src="Image.aspx" mce_src="Image.aspx" /> </td>//image.aspx 后台代码public partial class Image : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { JScript.CreateCheckCodeImage(JScript.GenerateCheckCode()); } } //JScript.cs （常用JS调用)//随机数+字母 public static string GenerateCheckCode() { int number; char code; string checkCode = String.Empty; System.Random random = new Random(); for (int i = 0; i < 4; i++) { number = random.Next(); if (number % 2 == 0) code = (char)('0' + (char)(number % 10)); else code = (char)('A' + (char)(number % 26)); checkCode += code.ToString(); } HttpContext.Current.Response.Cookies.Add(new HttpCookie("CheckCode", checkCode)); return checkCode; }//验证码图片 public static 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 < 2; 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.Black), 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); HttpContext.Current.Response.ClearContent(); HttpContext.Current.Response.ContentType = "image/Gif"; HttpContext.Current.Response.BinaryWrite(ms.ToArray()); } finally { g.Dispose(); image.Dispose(); } }

//登陆（验证）页面后台代码protected void Button1_Click(object sender, EventArgs e) { string code = txtYanzheng.Text.ToString(); if(String.Compare(Request.Cookies["CheckCode"].Value, code, true) != 0) { JScript.Alert("验证码错误，请输入正确的验证码。", Page); return; } else { if (ba.Exists(TextBox1.Text.ToString(), TextBox2.Text.ToString())) { Session["name"] = TextBox1.Text.ToString(); Response.Redirect("chenggong.aspx"); } else { Response.Write("NO"); } } }//JS常用调用(JScript.cs)/// 弹出JavaScript小窗口 /// </summary> /// <param name="js">窗口信息</param> public static void Alert(string message, Page page) { #region string js = @"<Script language='JavaScript'> alert('" + message + "');</Script>"; //HttpContext.Current.Response.Write(js); if (!page.ClientScript.IsStartupScriptRegistered(page.GetType(), "alert")) { page.ClientScript.RegisterStartupScript(page.GetType(), "alert", js); } #endregion }