ashx生成验证码存Session时的需要实现一个标记方法的接口IRquiresSessionState,否则存Session时会报错

using Common;
using System.Web;

using System.Web.SessionState;

namespace WebApp2019ASPX._09Session
{
    /// <summary>
    /// _04GenerateValidateCode 的摘要说明
    /// </summary>
    public class _04GenerateValidateCode : IHttpHandler,IRequiresSessionState
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/plain";
            //context.Response.Write("Hello World");
            //生成验证码图像过程 : ValicateCode实例化-->生成验证码文本--->存到Session中供与输入验证码比对--->文本生成验证码图片让用户参照输入
            ValidateCode vc = new ValidateCode();
            string strCode= vc.CreateValidateCode(4);
            context.Session["validateCodeSession"] = strCode;//供输入时提取与输入比对
            vc.CreateValidateGraphic(strCode, context);
        }

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