一般处理程序生成验证码

 

DrawingOnWebPage.ashx页

 

using System;
using System.Collections;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Xml.Linq;
using System.Drawing.drawing2d;
using System.Drawing;



namespace AspTechnicalBase
{
    /// <summary>
    /// $codebehindclassname$ 的摘要说明
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    public class DrawingOnWebPage : IHttpHandler
    {    /// <summary>
        /// 绘图的相关参数
        /// </summary>
        private const int ImageWidth = 600;  //指定验证码的宽度
        private const int ImageHeight = 100; //指定验证的高度
        private const int codeLength = 4;// 指定生成几个验证码

        /// <summary>
        /// 响应HTTP请求
        /// </summary>
        /// <param name="context">HTTP请求的上下文对象</param>
        public void ProcessRequest(HttpContext context)
        {
            string str = createCode( codeLength ) as string;
            //开辟一个ImageWidth像素宽、ImageHeight像素高的绘图缓冲区
            Bitmap bmp = new Bitmap(ImageWidth,ImageHeight);
            //创建绘图表面对象，引用这一绘图缓冲区
            Graphics g = Graphics.FromImage(bmp);

            //生成一个渐变的画刷
            Brush br = new LinearGradientBrush(new Point(0,0),new Point(ImageWidth,Color.Black,Color.Blue);
            //用渐变画刷填充绘图表面
            g.FillRectangle(br,g.ClipBounds);

           
            Font f = new Font("宋体",30);
            //输出文字
            g.DrawString(str,f,Brushes.Yellow,new PointF(40,20));

            //将结果输出到浏览器
            context.Response.ContentType = "Image/JPEG";
            context.Response.Clear();
            context.Response.BufferOutput = true;
            bmp.Save(context.Response.OutputStream,System.Drawing.Imaging.ImageFormat.Jpeg);

            //释放相关的绘图对象
            br.dispose();
            f.dispose();
            g.dispose();
            bmp.dispose();


        }
        /// <summary>
        /// 是否自动缓存此对象以供下次复用
        /// </summary>
        ///



        private string createCode( int codeLength )
        {
            string so = "1,2,3,4,5,6,7,8,9,a,b,c,d,e,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,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[] strArr = so.Split(',');
            string code = "";
            Random rand = new Random();
            for (int i = 0; i < codeLength; i++)
            {
                code += strArr[rand.Next(0,strArr.Length)];
            }

            return code;

        }
       




        public bool IsReusable
        {
            get
            {
                return false;
            }
        }

    }
}

 

 

然后是显示验证码的页面 的html中加入<img src="DrawingOnWebPage.ashx"  id="poloy" alt="点击刷新"  /> 在</head>之前一行加入javascript脚本语言如下(当然写在JS文件里面更好): <script type="text/javascript"> function reloadcode(){ document.getElementById("poloy").src ="DrawingOnWebPage.ashx"; } </script>