<%@ WebHandler Language="C#" Class="ValidataeCodeHandler" %>using System;
using System.Web;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;
using System.Drawing.Imaging;public class ValidataeCodeHandler : IHttpHandler, System.Web.SessionState.IRequiresSessionState
{public void ProcessRequest(HttpContext context){//请求类型：获取验证码图片，匹配验证码string type = context.Request["type"];if (type == "math"){if (string.IsNullOrEmpty(context.Request["code"]))context.Response.Write(2);else if (string.IsNullOrEmpty("" + context.Session["yqcode" + context.Request["id"]])){context.Response.Write(3);}else{if ("" + context.Session["yqcode" + context.Request["id"]] == context.Request["code"] + "")context.Response.Write(1);elsecontext.Response.Write(0);}}else{context.Response.ContentType = "image/gif";string validateCode = CreateValidateCode(context);//生成验证码 Bitmap bitmap = new Bitmap(imgWidth, imgHeight);//生成Bitmap图像 DisturbBitmap(bitmap); //图像背景 DrewValidateCode(bitmap, validateCode);//绘制验证码图像 bitmap.Save(context.Response.OutputStream, ImageFormat.Gif);//保存图像，等待输出
context.Response.Write(bitmap);}}//  private int codeLen = 4;//验证码长度 private int fineness = 85;//图片清晰度 private int imgWidth = 48;//图片宽度 private int imgHeight = 24;//图片高度 private string fontFamily = "Times New Roman";//字体名称 private int fontSize = 14;//字体大小 //private int fontStyle = 0;//字体样式 private int posX = 0;//绘制起始坐标X private int posY = 0;//绘制坐标Y private string CreateValidateCode(HttpContext context) //生成验证码
    {string validateCode = "";Random random = new Random();// 随机数对象 validateCode = random.Next(1000, 9999) + "";//for (int i = 0; i < codeLen; i++)//循环生成每位数值 //{//    int n = random.Next(10);//数字 //    validateCode += n.ToString();//}context.Session["yqcode" + context.Request["id"]] = validateCode;//保存验证码 这Session是在前台调用的。return validateCode;// 返回验证码
    }private void DisturbBitmap(Bitmap bitmap)//图像背景
    {Random random = new Random();//通过随机数生成 for (int i = 0; i < bitmap.Width; i++)//通过循环嵌套，逐个像素点生成
        {for (int j = 0; j < bitmap.Height; j++){if (random.Next(90) <= this.fineness)bitmap.SetPixel(i, j, Color.LightGray);}}}private void DrewValidateCode(Bitmap bitmap, string validateCode)//绘制验证码图像
    {Graphics g = Graphics.FromImage(bitmap);//获取绘制器对象 Font font = new Font(fontFamily, fontSize, FontStyle.Bold);//设置绘制字体 g.DrawString(validateCode, font, Brushes.Black, posX, posY);//绘制验证码图像
    }public bool IsReusable{get{return false;}}}