动态生成验证码

知识点：

1. 对图像的操作

 

问题：

动态生成验证码

解决方案

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

using System;
using System.Web;
using System.Drawing;
using System.IO;

public class ValidateCode : IHttpHandler {
    
    public void ProcessRequest (HttpContext context) {
        context.Response.ContentType = "text/plain";
        //context.Response.Write("Hello World");
        Random r = new Random();
        int n = r.Next(10000,100000);
        CreateValidateGraphic(n.ToString(),context);
    }
    /// <summary>
    /// 创建验证码的图片
    /// </summary>
    /// <param name="containsPage">要输出到的page对象</param>
    /// <param name="validateNum">验证码</param>
    public void CreateValidateGraphic(string validateCode, HttpContext context)
    {
        Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 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);
            //画图片的干扰线
            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 Font("Arial", 12, (FontStyle.Bold | 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(validateCode, font, brush, 3, 2);
            //画图片的前景干扰点
            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);
            //保存图片数据
            MemoryStream stream = new MemoryStream();
            image.Save(stream, System.Drawing.Imaging.ImageFormat.Jpeg);
            //输出图片流
            context.Response.Clear();
            context.Response.ContentType = "image/jpeg";
            context.Response.BinaryWrite(stream.ToArray());
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }
    }

    public bool IsReusable {
        get {
            return false;
        }
    }

}