一般处理程序实现验证码

首先创建一个一般处理程序，添加代码如下：

public class Handler1 : IHttpHandler,System.Web.SessionState.IRequiresSessionState
    {
        private static Random random = new Random();
        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "image/jpeg";

            Image image = new Bitmap(60, 30);
           
            //随即产生一个四位数
            int code = random.Next(1000, 10000);
            string codeString = code.ToString();

            //验证码放进Session中以便代码回传的时候验证用户输入的验证码是否正确
            context.Session["Code"] = codeString;

            using (Graphics g = Graphics.FromImage(image))
            {
                g.Clear(Color.WhiteSmoke);
                StringFormat sf = new StringFormat();
                sf.Alignment = StringAlignment.Center;
                sf.LineAlignment = StringAlignment.Center;
                g.DrawString(codeString,new Font("Arial",14),Brushes.Blue,new RectangleF(0,0,image.Width,image.Height),sf);
                image.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }

在asp页面中调用上面的处理程序：

 <asp:Image ID="Image1" runat="server" ImageUrl="~/Handler1.ashx" />

以上代码就OK了。