asp.net下產生英文字元數字驗證碼的代碼

using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using System.Drawing; using System.Drawing.Drawing2D; public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Bitmap bmp = new Bitmap(50, 25); Graphics g = Graphics.FromImage(bmp); SolidBrush sb = new SolidBrush(getColor()); g.DrawString(CheckNumber(), new Font("宋體", 16), sb, 0, 0); bmp.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Gif); } public static string CheckNumber() { string checkcode = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; int len = 4; string tmpstr = ""; int iRandNum; Random rnd = new Random(); for (int i = 0; i < len; i++) { iRandNum = rnd.Next(checkcode.Length); tmpstr += checkcode[iRandNum]; } return tmpstr; } private Color getColor() { Random r = new Random(); return Color.FromArgb(r.Next(256), r.Next(256), r.Next(256)); } }