C#生成验证码

------生成方法一

pageload（object sender, eventarges e）

{

 string chkCode = string.Empty;
        //颜色列表，用于验证码、噪线、噪点
        Color[] color = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };
        //字体列表，用于验证码
        string[] font = { "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact" };
        //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();
        //生成验证码字符串
        for (int i = 0; i < 4; i++)
        {
            chkCode += character[rnd.Next(character.Length)];
        }
        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);
        }
        //清除该页输出缓存，设置该页无缓存
        Response.Buffer = true;
        Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0);
        Response.Expires = 0;
        Response.CacheControl = "no-cache";
        Response.AppendHeader("Pragma", "No-Cache");
        //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);
            Response.ClearContent();
            Response.ContentType = "image/Png";
            //Response.BinaryWrite(ms.ToArray());           
           
        }
        finally
        {
            //显式释放资源
            bmp.Dispose();
            g.Dispose();
        }

}

------生成方法二

<%@ WebHandler Language="C#" class="yzCodeHandler" %>

using System;
using System.Web;
using System.Drawing;

public class yzCodeHandler : IHttpHandler , System.Web.SessionState.IRequiresSessionState
{
    public string charSet = "2,3,4,5,6,8,9,A,B,C,D,E,F,G,H,J,K,M,N,P,R,S,U,W,X,Y";
    public void ProcessRequest (HttpContext context) {
        string validateCode = CreateRandomCode(4);       
        context.Session["ValidateCode"] = validateCode;      
        CreateImage(validateCode, context);  
    }
 
    public bool IsReusable {
        get {
            return false;
        }
    }
    /// <summary>   
    /// 生成验证码         
    /// <param name="n">位数</param>  
    /// <returns>验证码字符串</returns>  
    private string CreateRandomCode(int n)  
    {      
        string[] CharArray = charSet.Split(',');   
        string randomCode = "";      
        int temp = -1;      
        Random rand = new Random();     
        for (int i = 0; i < n; i++)      
        {        
            if (temp != -1)   
            {           
                rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
            }            int t = rand.Next(CharArray.Length - 1);  
            if (temp == t)            {         
                return CreateRandomCode(n);        
            }            temp = t;        
            randomCode += CharArray[t];  
        }      
        return randomCode;
    }
    private void CreateImage(string checkCode, HttpContext context)  
    {       
        int iwidth = (int)(checkCode.Length * 13);      
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 23);       
        Graphics g = Graphics.FromImage(image);       
        Font f = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Italic | System.Drawing.FontStyle.Bold));        // 前景色       
        Brush b = new System.Drawing.SolidBrush(Color.Black);        // 背景色      
        g.Clear(Color.White);        // 填充文字       
        g.DrawString(checkCode, f, b, 0, 1);        // 随机线条       
        Pen linePen = new Pen(Color.Gray, 0);        Random rand = new Random();       
        for (int i = 0; i < 5; i++)        {           
            int x1 = rand.Next(image.Width);           
            int y1 = rand.Next(image.Height);           
            int x2 = rand.Next(image.Width);           
            int y2 = rand.Next(image.Height);           
            g.DrawLine(linePen, x1, y1, x2, y2);       
        }        // 随机点       
        for (int i = 0; i < 30; i++)      
        {          
            int x = rand.Next(image.Width); 
            int y = rand.Next(image.Height);       
            image.SetPixel(x, y, Color.Gray);      
        }        // 边框      
        g.DrawRectangle(new Pen(Color.Gray), 0, 0, image.Width - 1, image.Height - 1);        // 输出图片 
        System.IO.MemoryStream ms = new System.IO.MemoryStream();       
        image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);     
        context.Response.ClearContent();      
        context.Response.ContentType = "image/Jpeg";   
        context.Response.BinaryWrite(ms.ToArray());   
        g.Dispose();      
        image.Dispose();
    }   
}

----------------

验证方法

 if (txtValidateCode.Text.ToUpper().Trim() == Session["ValidateCode"].ToString().ToUpper().Trim())
        {
            //true
        }
else
{
  //false
}