刷新验证码（转载）

来源：互联网发布：vb浪涌保护器编辑：程序博客网时间：2024/05/01 20:22

生成随即图片
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;

public partial class common_CheckCode : System.Web.UI.Page
{
    private void Page_Load(object sender, System.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.Silver), x1, y1, x2, y2);
}

            Font font = new System.Drawing.Font("Arial", 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 < 100; 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.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);
            Response.ClearContent();
            Response.ContentType = "image/Gif";
            Response.BinaryWrite(ms.ToArray());
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }
    }
}

网页引用在引用页的ＣＳ里加上　　if (Request.Cookies["CheckCode"] == null)
        {
            Jscript.Alert("您的浏览器设置已被禁用 Cookies，您必须设置浏览器允许使用 Cookies 选项后才能使用本系统!");
            Jscript.GoHistory(-1);
            return;
        }

        if (String.Compare(Request.Cookies["CheckCode"].Value, validate.Text, true) != 0)
        {
            Jscript.Alert("验证码错误，请输入正确的验证码!");
            Jscript.GoHistory(-1);
            return;
        }
验证码要用ｃｏｏｋｉｅｓ存取所以要检测浏览器
最后在ｈｔｍｌ代码里加上
<img id="impanle"" src="common/CheckCode.aspx?" alt="看不清？单击"" onclick="this.src=this.src+'?' style="margin-right:40px;"/>

现在去单击你的验证码