obj.GetType().GetCustomAttributes

  1 using System;
  2 using System.Collections.Generic;
  3 using System.ComponentModel;
  4 using System.Data;
  5 using System.Drawing;
  6 using System.Text;
  7 using System.Reflection;
  8 using System.Windows.Forms;
  9 
 10 
 11 using System.Threading;
 12 
 13 using System.Collections.Specialized;
 14 
 15 namespace Test123
 16 {
 17     public partial class Form1 : Form
 18     {
 19 
 20         public Form1()
 21         {
 22             InitializeComponent();
 23         }
 24 
 25         private void Form1_Load(object sender, EventArgs e)
 26         {
 27 
 28         }
 29 
 30         public class TestAttri : Attribute
 31         {
 32             public string JJ { get; set; }
 33         }
 34 
 35         [TestAttri(JJ = "8899")]
 36         public class ClassTest2 : ClassTest { }
 37 
 38         public abstract class ClassTest { }
 39 
 40         private void button3_Click(object sender, EventArgs e)
 41         {
 42             ClassTest obj = new ClassTest2();
 43             Type type = obj.GetType();
 44             TestAttri att = GetCustomAttribute<TestAttri>(type, false);
 45             //(TestAttri)type.GetCustomAttributes(typeof(TestAttri), false).GetValue(0);
 46             //或者 (TestAttri)obj.GetType().GetCustomAttributes(typeof(TestAttri), false)[0];
 47             att.JJ = "rich";
 48 
 49             //需要特别注意的地方：
 50             //GetCustomAttributes 方法每次都返回新的实例
 51             //每次获取 io 的 CustomAttributes 都是一个新的副本
 52 
 53             MessageBox.Show(att.JJ);
 54 
 55             ((TestAttri)obj.GetType().GetCustomAttributes(typeof(TestAttri), false)[0]).JJ = "jigjig";
 56             MessageBox.Show(((TestAttri)obj.GetType().GetCustomAttributes(typeof(TestAttri), false)[0]).JJ);
 57         }
 58 
 59         private static Dictionary<MemberInfo, Object> _dicCache1 = new Dictionary<MemberInfo, Object>();
 60         private static Dictionary<MemberInfo, Object> _dicCache2 = new Dictionary<MemberInfo, Object>();
 61 
 62         public static TAttribute[] GetCustomAttributes<TAttribute>(MemberInfo member, Boolean inherit)
 63         {
 64             if (member == null)
 65             {
 66                 return new TAttribute[0];
 67             }
 68 
 69             // 根据是否可继承，分属两个缓存集合
 70             var cache = inherit ? _dicCache1 : _dicCache2;
 71 
 72             Object obj = null;
 73             if (cache.TryGetValue(member, out obj))
 74             {
 75                 return (TAttribute[])obj;
 76             }
 77             lock (cache)
 78             {
 79                 if (cache.TryGetValue(member, out obj))
 80                 {
 81                     return (TAttribute[])obj;
 82                 }
 83                 var atts = member.GetCustomAttributes(typeof(TAttribute), inherit) as TAttribute[];
 84                 var att = atts == null ? new TAttribute[0] : atts;
 85                 cache[member] = att;
 86                 return att;
 87             }
 88         }
 89 
 90         public static TAttribute GetCustomAttribute<TAttribute>(MemberInfo member, Boolean inherit)
 91         {
 92             var atts = member.GetCustomAttributes<TAttribute>(inherit);
 93             if (atts == null || atts.Length < 1)
 94             {
 95                 return default(TAttribute);
 96             }
 97             return atts[0];
 98         }
 99 
100     }
101 
102 }