.NET: C#: Attribute

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using MySql.Data;
 6 using MySql.Data.Entity;
 7 using MySql.Data.MySqlClient;
 8 using System.IO;
 9 using System.Data;
10 using System.Diagnostics;
11 using System.Runtime.InteropServices;
12 using System.Reflection;
13 
14 namespace test4
15 {
16     [Flags]
17     public enum Animal
18     {
19         Dog = 0x0001,
20         Cat = 0x0002,
21         Duck = 0x0004,
22         Chicken = 0x0008
23     }
24     [AttributeUsage(AttributeTargets.Class)]
25     public class VersionAttribute : Attribute
26     {
27         public string Name { get; set; }
28         public string Date { get; set; }
29         public string Description { get; set; }
30     }
31     [Version(Name = "yingzhongwen", Date = "2015-06-25", Description = "yingzhongwen‘s class")]
32     public class MyClass
33     {
34         public void SayHello()
35         {
36             Console.WriteLine("Hello, my .NET world.");
37         }
38     }
39     class Program
40     {
41         [DllImport("User32.dll")]
42         public static extern int MessageBox(int hParent, string msg, string caption, int type);
43         static void Main(string[] args)
44         {
45             var info = typeof(MyClass);
46             var classAttribute = (VersionAttribute)Attribute.GetCustomAttribute(info, typeof(VersionAttribute));
47             Console.WriteLine(classAttribute.Name);
48             Console.WriteLine(classAttribute.Date);
49             Console.WriteLine(classAttribute.Description);
50             object obj = Activator.CreateInstance(typeof(MyClass));
51             MethodInfo mi = (typeof(MyClass)).GetMethod("SayHello");
52             mi.Invoke(obj, null);
53 
54             Animal animals = Animal.Cat | Animal.Dog;
55             Console.WriteLine(animals.ToString());
56             Console.WriteLine((MessageBox(0, "How to use attribute in .NET", "anytao_net", 0)));
57         }     
58     }
59 }