关于特性的理解和使用

将特性插入，就是插入一个标志？然后再类typeof中存在一（字段？方法？）对多（特性）

 

当调用特性的方法的时候就是调用想对应类的 方法；

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace 特性
{
    class Program
    {
        static void Main(string[] args)
        {
            A a = new A() {mypeproty=""};
            bAttribute.IsPropetyNull(a);
            aAttribute.print();
            System.Console.Read();
        }
        public class bAttribute : System.Attribute
        {
            /// <summary>
            /// 检查应用是否为空？为空返回true;
            /// </summary>
            /// <param name="ob"></param>
            /// <returns></returns>
            static public bool IsPropetyNull(object ob)
            {
                var ObType = ob.GetType();
                foreach (var propety in ObType.GetProperties())
                {
                    var atrributes = propety.GetCustomAttributes(typeof(bAttribute), false);
                    if (atrributes.Length > 0)
                    {
                        if (propety.GetValue(ob) == null)

                        {
                            Console.WriteLine("为空");
                            return true;
                        }
                        else
                        {
                            Console.WriteLine("不为空");
                            return false;
                        }
                    }



                }
                Console.WriteLine("不为空");
                return false;
            }

        }
        public class aAttribute : System.Attribute
        {
            public static void print()
            {
                Console.WriteLine("hello, a Attribute!");
            }
        }

        class A
        {
           [bAttribute]
            

            public string mypeproty
            {
                set;
                get;
            }
            //[a]
            [bAttribute]
            public string myid
            {
                set;

using System.Reflection;

// An enumeration of animals. Start at 1 (0 = uninitialized).
public enum Animal
{
    // Pets.
    Dog = 1,
    Cat,
    Bird,
}

// A custom attribute to allow a target to have a pet.
public class AnimalTypeAttribute : Attribute
{
    // The constructor is called when the attribute is set.
    public AnimalTypeAttribute(Animal pet)
    {
        thePet = pet;
        Console.WriteLine("what a fuck programe!");
    }

    // Keep a variable internally ...
    protected Animal thePet;

    // .. and show a copy to the outside world.
    public Animal Pet
    {
        get { return thePet; }
        set { thePet = value; }
    }
}

// A test class where each method has its own pet.
class AnimalTypeTestClass
{
    [AnimalType(Animal.Dog)]
    public void DogMethod() { }

    [AnimalType(Animal.Cat)]
    public void CatMethod() { }

    [AnimalType(Animal.Bird)]
    public void BirdMethod() { }
}

class DemoClass
{
    static void Main(string[] args)
    {
        AnimalTypeTestClass testClass = new AnimalTypeTestClass();
        Type type = testClass.GetType();
        // Iterate through all the methods of the class.
        foreach (MethodInfo mInfo in type.GetMethods())
        {
            // Iterate through all the Attributes for each method.
            foreach (Attribute attr in
                Attribute.GetCustomAttributes(mInfo))
            {
                // Check for the AnimalType attribute.
                if (attr.GetType() == typeof(AnimalTypeAttribute))
                    Console.WriteLine(
                        "Method {0} has a pet {1} attribute.",
                        mInfo.Name, ((AnimalTypeAttribute)attr).Pet);
            }

           
        }
        Console.Read();
    }
}
/*
 * Output:
 * Method DogMethod has a pet Dog attribute.
 * Method CatMethod has a pet Cat attribute.
 * Method BirdMethod has a pet Bird attribute.
 */

 

get;

            }

        }
    }
}

 

以上

IsPropetyNull 是自定义的特性，它并没有改写 system.Attribute 的特性函数；

对于特性可以标志（？）字段或者方法的时候 调用构造函数，然后当需要的时候 创建对象？
以上是msdn上的 例子

系统定义的特性有哪些？

 

using System.Reflection;
// An enumeration of animals. Start at 1 (0 = uninitialized).public enum Animal{    // Pets.    Dog = 1,    Cat,    Bird,}
// A custom attribute to allow a target to have a pet.public class AnimalTypeAttribute : Attribute{    // The constructor is called when the attribute is set.    public AnimalTypeAttribute(Animal pet)    {        thePet = pet;        Console.WriteLine("what a fuck programe!");    }
    // Keep a variable internally ...    protected Animal thePet;
    // .. and show a copy to the outside world.    public Animal Pet    {        get { return thePet; }        set { thePet = value; }    }}
// A test class where each method has its own pet.class AnimalTypeTestClass{    [AnimalType(Animal.Dog)]    public void DogMethod() { }
    [AnimalType(Animal.Cat)]    public void CatMethod() { }
    [AnimalType(Animal.Bird)]    public void BirdMethod() { }}
class DemoClass{    static void Main(string[] args)    {        AnimalTypeTestClass testClass = new AnimalTypeTestClass();        Type type = testClass.GetType();        // Iterate through all the methods of the class.        foreach (MethodInfo mInfo in type.GetMethods())        {            // Iterate through all the Attributes for each method.            foreach (Attribute attr in                Attribute.GetCustomAttributes(mInfo))            {                // Check for the AnimalType attribute.                if (attr.GetType() == typeof(AnimalTypeAttribute))                    Console.WriteLine(                        "Method {0} has a pet {1} attribute.",                        mInfo.Name, ((AnimalTypeAttribute)attr).Pet);            }
                   }        Console.Read();    }}/* * Output: * Method DogMethod has a pet Dog attribute. * Method CatMethod has a pet Cat attribute. * Method BirdMethod has a pet Bird attribute. */