【转载】ASP.NET 生成验证码

直接上code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.Drawing.Imaging;
 
namespace AnalyzerExtAuth.Common
{
    public partial class ValidateCodeImg : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            //验证码中可能会出现的字符集合
            String checkCodeString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
            //验证码字符集合的长度
            int length = checkCodeString.Length;
            //设置绘制验证码的字体,并设置为粗体并倾斜
            Font font = new Font("宋体", 24, (FontStyle.Bold | FontStyle.Italic));
            //绘制验证码的笔刷
            Brush brush = null;
            //绘制验证码文字的颜色
            Color brushColor = new Color();
            //验证码的字符串
            String checkCode = String.Empty;
            //当前要绘制的验证字符
            String code = String.Empty;
            //要生成的验证码图片对象
            Bitmap image = new Bitmap(80, 40);
            //绘图画板
            Graphics graphics = Graphics.FromImage(image);
            //填充背景为白色
            graphics.Clear(Color.White);
 
            //创建随机数对象
            Random random = new Random();
 
            int x1, x2, y1, y2;
            Pen pen = new Pen(Color.Silver);
            //画背景噪音线
            for (int i = 1; i <= 25; i++)
            {
                x1 = random.Next(image.Width);
                y1 = random.Next(image.Height);
                x2 = random.Next(image.Width);
                y2 = random.Next(image.Height);
                graphics.DrawLine(pen, x1, y1, x2, y2);
            }
 
            for (int i = 0; i < 4; i++)
            {
                //为了保证取的字符索引不超过0-35之间
                //取任何数的余数都肯定小于自身
                //采用当前时间的毫秒 % 验证码字符的总长度=当前验证字符
                int current = random.Next(DateTime.Now.Millisecond) % length;
                //截取验证字符
                code = checkCodeString.Substring(current, 1);
                //拼接到验证码的字符串
                checkCode += code;
                //随机生成验证码字符的颜色
                brushColor = Color.FromArgb(random.Next(256), random.Next(256), random.Next(256));
                //笔刷的颜色
                brush = new SolidBrush(brushColor);
                //绘制刚刚得到的字符串
                graphics.DrawString(code, font, brush, i * 15 + 2, 2);
            }
 
            Response.Clear();
            Response.ContentType = "image/pjpeg";
            //在Session中保存验证码字符串,以便与用户输入进行比较
            Session["CheckCode"] = checkCode;
            image.Save(Response.OutputStream, ImageFormat.Jpeg);
            image.Dispose();
            Response.End();
 
        }
    }
}

//验证控件
< img src = "ValidateCode.aspx" width = "60" height = "25" style = "cursor: pointer;" onclick = "this.src='ValidateCode.aspx?id'+Math.random()*10000" / >