asp.net 创建验证码

最新推荐文章于 2024-02-20 23:57:02 发布

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#验证码

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本文介绍了一种使用 C# 生成包含字母数字组合的验证码图片的方法。通过随机选择字符并绘制到图片上，同时加入干扰线来提高识别难度。该方法适用于网站登录等场景，帮助验证用户身份。

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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 WebApplication7
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            createCheckImage(checkcode());
        }

        public string checkcode()
        {
            string result = string.Empty;
            char[] resoure = new char[] { '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', 'A', 'B', 'D', 'D',
                'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 
                'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
            int length = 4;
            System.Random random = new Random();
            
            for (int i = 0; i < length; i++)
            {
                char t=resoure[random.Next(resoure.Length)];
                result += t;
            }



            return result;
        }
        public void createCheckImage(string code)
        {
            int wid = 80;
            int len = 40;
            System.Random random = new Random();
            System.Drawing.Bitmap image = new Bitmap(wid, len);
            System.Drawing.Graphics g = Graphics.FromImage(image);

            g.Clear(Color.White);
            for (int i = 0; i < 25; i++)
            {
                int x1 = random.Next(wid);
                int y1 = random.Next(len);
                int x2 = random.Next(wid);
                int y2 = random.Next(len);
                g.DrawLine(new Pen(Color.Silver),x1,y1,x2,y2);
            }
            Font font=new Font("Arial",20);


            int x=0,y=0;
            for (int i = 0; i < code.Length; i++)
            {
                char c = code[i];

                g.DrawString(c.ToString(), font, new SolidBrush(Color.Black), x, y);
                x += 17;
               // y += 10;
            }
            g.DrawRectangle(new Pen(new SolidBrush(Color.Black)), 0,0,wid-1,len-1);
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            image.Save(ms, ImageFormat.Gif);

            Response.ClearContent();
            Response.ContentType = "image/Gif";
            Response.BinaryWrite(ms.ToArray());


            g.Dispose();
            image.Dispose();
            
        }
    }
}