验证码

 

首先创建一个aspx页面，用来生成验证码的图片。

 

public partial class ValidationCode : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { string checkCode = this.CreateRandomCode(6); Session["CheckCode"] = checkCode; CreateImage(checkCode); } 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,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(36); if (temp != -1 && temp == t) { return CreateRandomCode(codeCount); } temp = t; randomCode += allCharArray[t]; } return randomCode; } private void CreateImage(string checkCode) { System.Drawing.Bitmap image = new System.Drawing.Bitmap(Convert.ToInt32(Math.Ceiling((decimal)(checkCode.Length * 16))), 28); Graphics g = Graphics.FromImage(image); try { Random random = new Random(); g.Clear(Color.AliceBlue); 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.White), x1, y1, x2, y2); } Font font = new System.Drawing.Font("Arial", 14, System.Drawing.FontStyle.Bold); //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, new SolidBrush(Color.Red), 2, 2); 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())); } 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(); } } }

调用的页面：

<form id="form1" runat="server"> <div> <iframe src="ValidationCode.aspx" width="150px" height="40px" style="border:none;"></iframe> <asp:TextBox ID="txtValidationCode" runat="server"></asp:TextBox><asp:Label ID="lblResult" runat="server"></asp:Label><br /> <asp:Button ID="btnOK" runat="server" Text="OK" OnClick="btnOK_Click" /> </div> </form>

protected void btnOK_Click(object sender, EventArgs e) { if (this.txtValidationCode.Text.Trim().Equals(Session["CheckCode"].ToString(), StringComparison.CurrentCultureIgnoreCase)) { this.lblResult.Text = "OK"; } else { this.lblResult.Text = "ERROR"; } }