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源程序如下:
using System;
using System.Drawing; using System.Drawing.Imaging; using System.Collections.Generic; using System.Text; using System.IO; using System.Web; /// <summary> /// /// ** asp.net(C#) 生成验证码 ** /// /// File: GenerateCheckCode.cs /// /// Author: 周振兴 (Zxjay 飘遥) /// /// Date: 07-04-10 /// /// http://www.cnblogs.com/zxjay /// /// </summary> public class GenerateCheckCode { private static string chkCode; public static MemoryStream GenCheckCode() { //颜色列表,用于验证码、噪线、噪点 Color[] color ={ Color.Tomato, Color.OrangeRed, Color.Olive, Color.Gold, Color.GreenYellow, Color.Blue, Color.LawnGreen, Color.Lime, Color.MediumSpringGreen, Color.Aqua, Color.RoyalBlue, Color.MediumBlue, Color.BlueViolet, Color.MediumOrchid, Color.Fuchsia, Color.DeepPink, Color.HotPink }; //字体列表,用于验证码 string[] font = { "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU" }; //验证码的字符集,去掉了一些容易混淆的字符 char[] character ={ '2', '3', '4', '5', '6', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W', 'X', 'Y' }; Random rnd = new Random(); chkCode = string.Empty; //生成验证码字符串 for (int i = 0; i < 4; i++) { chkCode += character[rnd.Next(character.Length)]; } HttpContext.Current.Session["checkcode"] = chkCode; Bitmap bmp = new Bitmap(100, 40); Graphics g = Graphics.FromImage(bmp); g.Clear(Color.White); //画噪线 for (int i = 0; i < 10; i++) { int x1 = rnd.Next(100); int y1 = rnd.Next(40); int x2 = rnd.Next(100); int y2 = rnd.Next(40); Color clr = color[rnd.Next(color.Length)]; g.DrawLine(new Pen(clr), x1, y1, x2, y2); } //画验证码字符串 for (int i = 0; i < chkCode.Length; i++) { string fnt = font[rnd.Next(font.Length)]; Font ft = new Font(fnt, 18); Color clr = color[rnd.Next(color.Length)]; g.DrawString(chkCode[i].ToString(), ft, new SolidBrush(clr), (float)i * 20 + 8, (float)8); } //画噪点 for (int i = 0; i < 100; i++) { int x = rnd.Next(bmp.Width); int y = rnd.Next(bmp.Height); Color clr = color[rnd.Next(color.Length)]; bmp.SetPixel(x, y, clr); } //画边框 Color col = color[rnd.Next(color.Length)]; g.DrawLine(new Pen(color[rnd.Next(color.Length)]), 0, 0, bmp.Width - 1, 0); g.DrawLine(new Pen(color[rnd.Next(color.Length)]), 0, 0, 0, bmp.Height - 1); g.DrawLine(new Pen(color[rnd.Next(color.Length)]), bmp.Width - 1, 0, bmp.Width - 1, bmp.Height - 1); g.DrawLine(new Pen(color[rnd.Next(color.Length)]), 0, bmp.Height - 1, bmp.Width - 1, bmp.Height - 1); //清除该页输出缓存,设置该页无缓存 HttpContext.Current.Response.Buffer = true; HttpContext.Current.Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0); HttpContext.Current.Response.Expires = 0; HttpContext.Current.Response.CacheControl = "no-cache"; HttpContext.Current.Response.AddHeader("Pragma", "No-Cache"); HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache); //将验证码图片写入内存流,并将其以 "image/Png" 格式输出 MemoryStream ms = new MemoryStream(); try { bmp.Save(ms, ImageFormat.Png); HttpContext.Current.Response.ClearContent(); HttpContext.Current.Response.ContentType = "image/Png"; return ms; } catch (Exception) { return null; } finally { //显式释放资源 bmp.Dispose(); g.Dispose(); } } } 使用方法如下: 新建名为 GenerateCheckCode.aspx 的文件,文件的内容为:
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