.net之特性(Attribute)

看了一些关于这方面的文档，自我总结：

    特性(Attribute)就是对一个方法或类做的一个额外的属性说明，也就是附加说明

下面是我自己抄的一个实例程序：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;

namespace SomeTest
{
    
    class Program
    {

        static void Main(string[] args)
        {
            demo d = new demo();
            string username = "Lucy";
            MethodInfo mi = d.GetType().GetMethod("Test");
            if (mi == null) return;
            AllowExecuteAttribute att = Attribute.GetCustomAttribute(mi,typeof(AllowExecuteAttribute)) as AllowExecuteAttribute;
            if (att == null) return;
            if (att.Check(username))
                Console.WriteLine("允许执行");
            else
                Console.WriteLine("不允许执行");


            Console.ReadKey();
        }
    }

    class demo
    {
        [AllowExecute("jack,Tom")]
        public void Test()
        { 
            
        }
    }

    /// <summary> 
    /// 标识某方法允许执行的用户 
    /// </summary> 
    public class AllowExecuteAttribute : Attribute
    {
        /// <summary> 
        ///  
        /// </summary> 
        /// <param name="allowedUsers">允许执行的用户名的串联字符串</param> 
        public AllowExecuteAttribute(string allowedUsers)
        {
            this._allowedUsers = allowedUsers;
        }
        private string _allowedUsers;

        public bool Check(string userName)
        {
            return this._allowedUsers.ToLower().IndexOf(userName.ToLower()) > -1;
        }
    }
}

下面是公司项目中MVC中对AuthorizeAttribute特性的一些使用方法：

public class SingleUserAuthorize : AuthorizeAttribute
    {
        [ValidateInput(false)]
        protected override bool AuthorizeCore(HttpContextBase httpContext)
        {
            Hashtable userOnline = (Hashtable)(httpContext.Application["Online"]);
            if (userOnline != null)
            {
                IDictionaryEnumerator idE = userOnline.GetEnumerator();
                string strkey = string.Empty;
                if (userOnline.Count > 0)
                {
                    while (idE.MoveNext())
                    {
                        //登录时判断保存的session是否与当前页面的session相同
                        if (userOnline.Contains(httpContext.Session.SessionID))
                        {
                            if (idE.Key != null && idE.Key.ToString().Equals(httpContext.Session.SessionID))
                            {
                                //判断当前session保存的值是否为被注销值
                                if (idE.Value != null && "XXXXXX".Equals(idE.Value.ToString()))
                                {
                                    //验证被注销则清空session
                                    userOnline.Remove(httpContext.Session.SessionID);
                                    httpContext.Application.Lock();
                                    httpContext.Application["Online"] = userOnline;
                                    httpContext.Response.Write("<script>top.location.href='/Home/Message?message=offline';</script>");
                                    httpContext.Response.End();
                                    return false;
                                }
                            }
                        }
                        else
                        {
                            return false;
                        }
                    }
                    return true;
                }
                else
                {
                    return false;
                }
            }
            return false;
        }
    }

感觉这个违背了特性的设计初衷啊