.NET: C#: Attribute

ref: http://www.uml.org.cn/net/200810135.asp

ref: http://blog.csdn.net/okvee/article/details/2610349

注意这么几个问题：

1. Attribute和Property的区别

2. Attribute在编译中就有了，与面向对象中的多态不一样

3. 常用的Attribute: AttributeUsage, Flags, DllImport, Serializable, Conditional, 自定义特性

4. 可以通过反射来获取信息

5. Attribute本质上是一个类

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using MySql.Data;
 using MySql.Data.Entity;
 using MySql.Data.MySqlClient;
 using System.IO;
 using System.Data;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Reflection;

 namespace test4
 {
     [Flags]
     public enum Animal
     {
         Dog = 0x0001,
         Cat = 0x0002,
         Duck = 0x0004,
         Chicken = 0x0008
     }
     [AttributeUsage(AttributeTargets.Class)]
     public class VersionAttribute : Attribute
     {
         public string Name { get; set; }
         public string Date { get; set; }
         public string Description { get; set; }
     }
     [Version(Name = "yingzhongwen", Date = "2015-06-25", Description = "yingzhongwen's class")]
     public class MyClass
     {
         public void SayHello()
         {
             Console.WriteLine("Hello, my .NET world.");
         }
     }
     class Program
     {
         [DllImport("User32.dll")]
         public static extern int MessageBox(int hParent, string msg, string caption, int type);
         static void Main(string[] args)
         {
             var info = typeof(MyClass);
             var classAttribute = (VersionAttribute)Attribute.GetCustomAttribute(info, typeof(VersionAttribute));
             Console.WriteLine(classAttribute.Name);
             Console.WriteLine(classAttribute.Date);
             Console.WriteLine(classAttribute.Description);
             object obj = Activator.CreateInstance(typeof(MyClass));
             MethodInfo mi = (typeof(MyClass)).GetMethod("SayHello");
             mi.Invoke(obj, null);

             Animal animals = Animal.Cat | Animal.Dog;
             Console.WriteLine(animals.ToString());
             Console.WriteLine((MessageBox(, )));
         }
     }
 }