ASP.NET验证码实现（附源码）

 using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Drawing; using System.IO; namespace SecurityCodePic { public class DrawingSecurityCode { /// 
 /// 生成验证码，并返回 /// 
 ///  public string GetSecurityCode(int n) { string code = GenerateCheckCode(n); CreateCheckCodeImage(code); return code; } /// 
 /// 动态生成指定数目的随机数或字母 /// 
 /// 整数 /// 返回验证码字符串 private string GenerateCheckCode(int num) { int number;//定义变量 char code; string checkCode = String.Empty; //空字符串，只读 Random random = new Random(); //定义随机变量实例 for (int i=0; i  /// 根据验证码字符串生成验证码图片 ///  /// 验证码字符串 private void CreateCheckCodeImage(string checkCode) { if (checkCode == null || checkCode.Trim() == String.Empty) return; // 引用System.Drawing类库 Bitmap myImage = new Bitmap(80, 30);//生成一个指定大小的位图 Graphics graphics = Graphics.FromImage(myImage); //从一个位图生成一个画布 try { graphics.Clear(Color.White); //清除整个绘画面并以指定的背景色填充,这里是把背景色设为白色 Random random = new Random(); //实例化一个伪随机数生成器 //画图片的前景噪音点,这里有100个 for (int i = 0; i <100; i++) { int x = random.Next(myImage.Width); int y = random.Next(myImage.Height); myImage.SetPixel(x, y, Color.FromArgb(random.Next()));//指定坐标为x,y处的像素的颜色 } //画图片的背景噪音线,这里为2条 for (int i = 0; i <2; i++) { int x1 = random.Next(myImage.Width); int x2 = random.Next(myImage.Width); int y1 = random.Next(myImage.Height); int y2 = random.Next(myImage.Height); graphics.DrawLine(new Pen(Color.Black), x1, y1, x2, y2); //绘制一条坐标x1,y1到坐标x2,y2的指定颜色的线条，这里的线条为黑色 } Font font = new Font("Arial", 15, FontStyle.Bold); //定义特定的文本格式,这里的字体为Arial，大小为15,字体加粗 //根据矩形、起始颜色和结束颜色以及方向角度产生一个LinearGradientBrush实例---线性渐变 System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush( new Rectangle(0, 0, myImage.Width, myImage.Height),//在坐标0,0处实例化一个和myImage同样大小的矩形 Color.Blue, Color.Red, 1.2f, true); //绘制文本字符串 graphics.DrawString(checkCode, font, brush, 2, 2); //绘制有坐标对、宽度和高度指定的矩形---画图片的边框线 graphics.DrawRectangle(new Pen(Color.Silver), 0, 0, myImage.Width - 1, myImage.Height - 1); //创建其支持存储器为内存的流 MemoryStream ms = new MemoryStream(); //将此图像以指定格式保存到指定的流中 myImage.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); //这里是以gif的格式保存到内存中 HttpContext.Current.Response.ClearContent(); //清除缓冲区流中的所有内容输出 HttpContext.Current.Response.ContentType = "image/Gif"; //获取或设置输出流的HTTP MIME类型 HttpContext.Current.Response.BinaryWrite(ms.ToArray()); //将一个二进制字符串写入HTTP输出流 } finally { //释放占用资源 graphics.Dispose(); myImage.Dispose(); } } } } 

 using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace SecurityCodePic { /// 
 /// SecurityCode1 的摘要说明 /// 
 public class SecurityCode1 : IHttpHandler { public void ProcessRequest(HttpContext context) { DrawingSecurityCode sc = new DrawingSecurityCode(); string SecurityCode = sc.GetSecurityCode(6); } public bool IsReusable { get { return false; } } } } 

 <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="SecurityCode_Test.aspx.cs" Inherits="SecurityCodePic.SecurityCode_Test" %>