C# 之attribute

C# attribute  是不同于属性的， 我们自己写的attribute  姑且叫UserAttribute   继承于attribute 他的作用是什么。他只是做个标记，对类 属性做个标记。一个类或属性 或方法 可以有多个标记。 标记的目的是为了给别人使用时候，识别。从而做成相应的动作。貌似也实现了多态。使用方法 ：

1） 获得 Type  --> GetType

2)  获得Mothods --->GetMethods()

3) 获得Attributes -->GetCustomAttributes()

4) is 判断

using System;
using System.Reflection;
#region ll
namespace QueryAttribs
{
    public enum RemoteServers
    {
        JEANVALJEAN,
        JAVERT,
        COSETTE
    }
    public class RemoteObjectAttribute : Attribute
    {
        public RemoteObjectAttribute(RemoteServers Server)
        {
            this.server = Server;
        }
        protected RemoteServers server;
        public string Server
        {
            get
            {
               
                return RemoteServers.GetName(
                 typeof(RemoteServers), this.server);
            }
        }
    }
    [RemoteObject(RemoteServers.COSETTE)]
    class MyRemotableClass
    {
    }
    class Test
    {
        //[STAThread]
        //static void Main(string[] args)
        //{
        //    Type type = typeof(MyRemotableClass);
        //    foreach (Attribute attr in
        //     type.GetCustomAttributes(true))
        //    {
        //        RemoteObjectAttribute remoteAttr =
        //         attr as RemoteObjectAttribute;
        //        if (null != remoteAttr)
        //        {
        //            Console.WriteLine(
        //              "Create this object on {0}.",
        //              remoteAttr.Server);
        //        }
        //    }
        //    Console.ReadLine();
        //}
    }
}
#endregion


namespace MethodAttribs
{
  public class TransactionableAttribute : Attribute
  {
   public TransactionableAttribute()
   {
   }
  }
  class SomeClass
  {
   [Transactionable]
   public void Foo()
   {}
   public void Bar()
   {}
   [Transactionable]
   public void Goo()
   {}
  }
  class Test
  {
   [STAThread]
   static void Main(string[] args)
   {
       SomeClass ks = new SomeClass();
       MethodInfo[] arr=   ks.GetType().GetMethods();
        foreach (MethodInfo method in arr)
        foreach (Attribute attr in method.GetCustomAttributes(true))
        {
          if (attr is TransactionableAttribute)
          {
           Console.WriteLine(
            "{0} is transactionable.",
            method.Name);
          }
        }
        Console.WriteLine("#########");
    Type type = Type.GetType("MethodAttribs.SomeClass");
    foreach (MethodInfo method in type.GetMethods())
    {
     foreach (Attribute attr in
      method.GetCustomAttributes(true))
     {
      if (attr is TransactionableAttribute)
      {
       Console.WriteLine(
        "{0} is transactionable.",
        method.Name);
      }
     }
    }
    Console.ReadLine();
   }
  }
}