<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title></title> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> </head> <body> <img src="WaterMark.ashx" id="vimg" alt="" onclick="document.getElementById('vimg').src='this.src+='+?;" title="看不清楚，点击换一张" /> </body> </html>
using System; using System.Web; using System.Drawing; using System.Drawing.Drawing2D; using System.Web.SessionState; public class WaterMark : IHttpHandler, IRequiresSessionState // 要使用session必须实现该接口,记得要导入System.Web.SessionState命名空间 { public void ProcessRequest(HttpContext context) { string checkCode = GenCode(5); // 产生5位随机字符 context.Session["Code"] = checkCode; //将字符串保存到Session中，以便需要时进行验证 System.Drawing.Bitmap image = new System.Drawing.Bitmap(70, 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 int i; for (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.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 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); context.Response.ClearContent(); context.Response.ContentType = "image/Gif"; context.Response.BinaryWrite(ms.ToArray()); } finally { g.Dispose(); image.Dispose(); } } /// <summary> /// 产生随机字符串 /// </summary> /// <param name="num">随机出几个字符</param> /// <returns>随机出的字符串</returns> private string GenCode(int num) { string str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; char[] chastr = str.ToCharArray(); // string[] source ={ "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 code = ""; Random rd = new Random(); int i; for (i = 0; i < num; i++) { //code += source[rd.Next(0, source.Length)]; code += str.Substring(rd.Next(0, str.Length), 1); } return code; } public bool IsReusable { get { return false; } } }
