C# 生成简单验证码的代码

2015/05/02 37681

C#生成简单验证码的代码

html页面

<!--
    Document   : ASP.NET用一般处理程序生成验证码
    Created on : 2008-10-13 17：04
    Author     : 牛腩
-->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title></title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <script type="text/javascript">
        function change() {
            var imgNode = document.getElementById("vimg");
            imgNode.src = "WaterMark.ashx?t=" + (new Date()).valueOf();  // 这里加个时间的参数是为了防止浏览器缓存的问题
        }
    </script>
  </head>
  <body>
    <img src="WaterMark.ashx" id="vimg" alt="" /><input type="button" value="换一张图片" onclick="change()" />
  </body>
</html>

C#代码

//一般处理程序WaterMark.ashx的代码
<%@ WebHandler Language="C#" Class="WaterMark" %>
  
using System;
using System.Web;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Web.SessionState; 
  
public class WaterMark : IHttpHandler, IRequiresSessionState  // 要使用session必须实现该接口,记得要导入System.Web.SessionState命名空间
{
  
    public void ProcessRequest(HttpContext context)
    {
        string checkCode = GenCode(5);  // 产生5位随机字符
        context.Session["Code"] = checkCode; //将字符串保存到Session中，以便需要时进行验证
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(70, 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
            int i;
            for (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.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
            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);
            context.Response.ClearContent();
            context.Response.ContentType = "image/Gif";
            context.Response.BinaryWrite(ms.ToArray());
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }
    }
  
    /// <summary>
    /// 产生随机字符串
    /// </summary>
    /// <param name="num">随机出几个字符</param>
    /// <returns>随机出的字符串</returns>
    private string GenCode(int num)
    {
        string str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        char[] chastr = str.ToCharArray();
        // string[] source ={ "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 code = "";
        Random rd = new Random();
        int i;
        for (i = 0; i < num; i++)
        {
            //code += source[rd.Next(0, source.Length)];
            code += str.Substring(rd.Next(0, str.Length), 1);
        }
        return code;
  
    }
  
    public bool IsReusable
    {
        get
        {
            return false;
        }
    }
  
}

代码片段