.NET使用一般处理程序生成验证码!

  正在看CSDN上的ITCST上的王兴魁老师的AJAX技术入门,里面讲到了一个验证码的小程序,觉得蛮有用的,先记下来.

2024年11月28日22:13:46 改


watermark.ashx代码： 

<%@ WebHandler Language="C#" Class="WaterMark" %>

using System;
using System.Web;
using System.Drawing;
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(4);  // 产生4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();
        }
    }

    public bool IsReusable
    {
        get
        {
            return false;
        }
    }

    private string GenCode(int num)
    {
        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)];
        }
        return code;
    }

}
前端测试代码： 

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Login.aspx.cs" Inherits="Login" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title></title>
    <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>
    <form id="form1" runat="server">
        <div>
            <asp:TextBox ID="txtCaptcha" runat="server" Width="119px" MaxLength="6"
               
                TextMode="SingleLine" Placeholder="请输入验证码"></asp:TextBox>
            <img src="watermark.ashx" id="vimg" alt="" /><input type="button" value="换一张图片" onclick="change()" />

            <asp:Button ID="Button1" runat="server" Text="登录" OnClick="Button1_Click" />
        </div>
    </form>
</body>
</html>

测试代码后端： 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Login : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        string code = txtCaptcha.Text.Trim();
        string right_code = Session["Code"].ToString();
        if (code.ToLower() == right_code.ToLower())
        {
            Response.Write("验证码输入成功。");
        }
        else {
            Response.Write("验证码错误。");
        }
    }
}