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.net中我喜欢的两种验证码

一背景很单一的全黑色验证码
第一步：处理图片
image.aspx.cs:

using System;
using System.Data;
using System.Configuration;
using System.Collections;
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.Imaging;
using System.IO;
using System.Drawing;

public partial class image : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
         //生成4位的验证码
   string tmp = RndNum(4);
   HttpCookie a = new HttpCookie("ImageV",tmp);
   Response.Cookies.Add(a);
   this.ValidateCode(tmp);
    }

    private void ValidateCode(string VNum)
    {
        Bitmap Img = null;
        Graphics g = null;
        MemoryStream ms = null;

        int gheight = VNum.Length * 12;
        Img = new Bitmap(gheight, 25);
        g = Graphics.FromImage(Img);
        //背景颜色
        g.Clear(Color.White);
        //文字字体
        Font f = new Font("Arial Black", 10);
        //文字颜色
        SolidBrush s = new SolidBrush(Color.Black);
        g.DrawString(VNum, f, s, 3, 3);
        ms = new MemoryStream();
        Img.Save(ms, ImageFormat.Jpeg);
        Response.ClearContent();
        Response.ContentType = "image/Jpeg";
        Response.BinaryWrite(ms.ToArray());

        g.Dispose();
        Img.Dispose();
        Response.End();
    }

    private string RndNum(int VcodeNum)
    {
        string Vchar = "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[] VcArray = Vchar.Split(new Char[] { ',' });
        string VNum = "";
        int temp = -1;

Random rand = new Random();

        for (int i = 1; i < VcodeNum + 1; i++)
        {
            if (temp != -1)
            {
                rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));
            }

            int t = rand.Next(35);
            if (temp != -1 && temp == t)
            {
                return RndNum(VcodeNum);
            }
            temp = t;
            VNum += VcArray[t];
        }
        return VNum;
    }
}

第二步：调用的页面上login.aspx
<asp:Image ID="Image1" runat="server" Src="image.aspx" /><br />

二有背景的彩色验证码(网站用)
代码如下：
第一步:CheckCode.aspx

public partial class CheckCode : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        this.CreateCheckCodeImage(GenerateCheckCode());

}

    private string GenerateCheckCode()
    {
        int number;
        char code;
        string checkCode = String.Empty;

System.Random random = new Random();

        for (int i = 0; i < 5; i++)
        {
            number = random.Next();

            if (number % 2 == 0)
                code = (char)('0' + (char)(number % 10));
            else
                code = (char)('A' + (char)(number % 26));

checkCode += code.ToString();
}

Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));

return checkCode;
}

    private void CreateCheckCodeImage(string checkCode)
    {
        if (checkCode == null || checkCode.Trim() == String.Empty)
            return;

System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 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
            for (int 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.GreenYellow), x1, y1, x2, y2);
}

            Font font = new System.Drawing.Font("Verdana", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
            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
            for (int i = 0; i < 80; i++)
            {
                int x = random.Next(image.Width);
                int y = random.Next(image.Height);

image.SetPixel(x, y, Color.FromArgb(random.Next()));
}

//画图片的边框线
g.DrawRectangle(new Pen(Color.Red), 0, 0, image.Width - 1, image.Height - 1);

            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
            Response.ClearContent();
            Response.ContentType = "image/Gif";
            Response.BinaryWrite(ms.ToArray());
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }
    }
}

第二步:在要调用的页面上
UseCheckCode.aspx
<img src="Tools/CheckCode.aspx" alt="验证码" style="width: 60px; height: 24px" />

第三步：新建一般处理程序
ValidateImageHandler.ashx
%@ WebHandler Language="C#" Class="ValidateImageHandler" %>

using System;
using System.Web;
using System.Web.SessionState;
using System.Drawing;
using System.Drawing.Imaging;
using System.Text;

/**//// <summary>
/// ValidateImageHandler 生成网站验证码功能
/// </summary>
public class ValidateImageHandler : IHttpHandler, IRequiresSessionState
{
    int intLength = 5;               //长度
    string strIdentify = "Identify"; //随机字串存储键值，以便存储到Session中
    public ValidateImageHandler()
    {
    }

    /**//// <summary>
    /// 生成验证图片核心代码
    /// </summary>
    /// <param name="hc"></param>
    public void ProcessRequest(HttpContext hc)
    {
        //设置输出流图片格式
        hc.Response.ContentType = "image/gif";

        Bitmap b = new Bitmap(200, 60);
        Graphics g = Graphics.FromImage(b);
        g.FillRectangle(new SolidBrush(Color.YellowGreen), 0, 0, 200, 60);
        Font font = new Font(FontFamily.GenericSerif, 48, FontStyle.Bold, GraphicsUnit.Pixel);
        Random r = new Random();

        //合法随机显示字符列表
        string strLetters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
        StringBuilder s = new StringBuilder();

        //将随机生成的字符串绘制到图片上
        for (int i = 0; i < intLength; i++)
        {
            s.Append(strLetters.Substring(r.Next(0, strLetters.Length - 1), 1));
            g.DrawString(s[s.Length - 1].ToString(), font, new SolidBrush(Color.Blue), i * 38, r.Next(0, 15));
        }

        //生成干扰线条
        Pen pen = new Pen(new SolidBrush(Color.Blue), 2);
        for (int i = 0; i < 10; i++)
        {
            g.DrawLine(pen, new Point(r.Next(0, 199), r.Next(0, 59)), new Point(r.Next(0, 199), r.Next(0, 59)));
        }
        b.Save(hc.Response.OutputStream, ImageFormat.Gif);
        hc.Session[strIdentify] = s.ToString(); //先保存在Session中，验证与用户输入是否一致
        hc.Response.End();

    }

    /**//// <summary>
    /// 表示此类实例是否可以被多个请求共用(重用可以提高性能)
    /// </summary>
    public bool IsReusable
    {
        get
        {
            return true;
        }
    }
}