C# 反射通过GetCustomAttributes方法，获得自定义特性

http://blog.csdn.net/litao2/article/details/17633107

使用反射访问： 自定义属性的信息和对其进行操作的方法。

一、实例1

1、代码：

 如：System.Attribute[] attrs=System.Attribute.GetCustomAttributes(typeof(FirstClass));

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {

            PrintAuthorInfo(typeof(FirstClass));
            PrintAuthorInfo(typeof(SecondClass));
            PrintAuthorInfo(typeof(ThirdClass));
            Console.ReadKey();
        }

        private static void PrintAuthorInfo(System.Type t)
        {
            System.Console.WriteLine("
类型的 System.Type 对象是：{0}", t);
            System.Attribute[] attrs = System.Attribute.GetCustomAttributes(t);  //反射获得用户自定义属性

            foreach (System.Attribute attr in attrs)
            {
                if (attr is Author)
                {
                    Author a = (Author)attr;
                    System.Console.WriteLine("   名称：{0}, 版本： {1:f}", a.GetName(), a.version);
                }
            }
        }
    }



    [System.AttributeUsage(System.AttributeTargets.Class |
                       System.AttributeTargets.Struct,
                       AllowMultiple = true)
    ]//自定义特性类(应用特性的程序元素（是类或结构）,程序元素可以指定多个特性)
    public class Author : System.Attribute
    {
        string name;
        public double version;

        public Author(string name)
        {
            this.name = name;
            version = 1.0;  // Default value
        }

        public string GetName()
        {
            return name;
        }
    }

    [Author("H. Ackerman")]
    public class FirstClass
    {
        // ...
    }

    // No Author attribute
    public class SecondClass
    {
        // ...
    }

    [Author("H. Ackerman"), Author("M. Knott", version = 2.0)]
    public class ThirdClass
    {
        //程序元素可以指定多个特性
    }


}

 

2、效果：

二、实例2

1、代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Linq.Expressions;
using System.Collections.Specialized;
using System.Reflection;
using System.Data.Linq.Mapping;
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {

            PropertyInfo[] propertys = typeof(FirstClass).GetProperties();//返回FirstClass的所有公共属性
            if (propertys != null && propertys.Length > 0)
            {
                foreach (PropertyInfo p in propertys)
                {
                    object[] objAttrs = p.GetCustomAttributes(typeof(ColumnAttribute), true);//获取自定义特性
                    //GetCustomAttributes(要搜索的特性类型，是否搜索该成员的继承链以查找这些特性)
                    if (objAttrs != null && objAttrs.Length > 0)
                    {
                        ColumnAttribute attr = objAttrs[0] as ColumnAttribute;
                        Console.WriteLine("自定义特性Name："+p.Name+", 元数据："+attr);
                    }
                };
            }
            Console.ReadKey();
        }

    }



    public class FirstClass
    {
        private int _newsid = 0;

        /// <summary>
        /// 主键
        /// </summary>
        [Column(Name = "NewsId", DbType = "int", IsPrimaryKey = true, CanBeNull = false, IsDbGenerated = true)]
        public int NewsId
        {
            get
            {
                return this._newsid;
            }
            set
            {
                this._newsid = value;
            }
        }

        private string _newsimage = string.Empty;

        /// <summary>
        /// 资讯标题图片
        /// </summary>
        [Column(Name = "NewsImage", DbType = "varchar", IsPrimaryKey = false, CanBeNull = false, IsDbGenerated = false)]
        public string NewsImage
        {
            get
            {
                return this._newsimage;
            }
            set
            {
                this._newsimage = value;
            }
        }
    }
}

2、效果

其他：

FullName（获得System.Type的完全限定名，包括命名空间）

三、实例3 （设置指定实例 属性 的值）

FirstClass fClass = new FirstClass();
PropertyInfo pInstance = typeof(FirstClass).GetProperty("NewsId");//搜索具有指定名称的公共属性
pInstance.SetValue(fClass, 11, null);//设置指定实例 属性 的值

Console.WriteLine("新闻ID:"+fClass.NewsId);
Console.WriteLine("新闻图片:"+fClass.NewsImage);

//在4px的库内操作获取打印机

trv_LabelInvoice.Nodes.Clear();

string strText = string.Empty;
FieldInfo[] fields = typeof(EnumPrintName).GetFields();
foreach (FieldInfo field in fields)
{
strText = field.Name;

object[] arrAttributes = field.GetCustomAttributes(typeof(Attribute), true);
if (arrAttributes != null)
{
EnumAttribute objEnumAttribute = arrAttributes.FirstOrDefault(x => x.GetType().Name.Equals(typeof(EnumAttribute).Name)) as EnumAttribute;
if (objEnumAttribute != null)
{
strText = objEnumAttribute.Description;
}
}

if (trv_LabelInvoice.Nodes.IndexOfKey(field.Name) < 0)
{
trv_LabelInvoice.Nodes.Add(field.Name, strText);
}
}