[C#] 语法之Attribute

在c#中,定义类的成员,可以定义Property称为属性.Attribute就称为特性.

 

在FCL中,有内置的Attribute.如:

Condition[Attribute]:在什么条件可以调用.(只能作用于返回值为void的方法上)

Obsolete:方法弃用.支持禁用.

代码1:

class Program

    {

        static void Main(string[] args)

        {

            Func();

            Console.ReadLine();

        }



        [Obsolete("you can use Func to replace this",true)]

        private static void Test()

        {

            Console.WriteLine("noooo");

        }



        private static void Func()

        {

            Console.WriteLine("yesss");

        }

    }

    class T

    {

        [Conditional("DEBUG")]

        public static void M(string str)

        {

            Console.WriteLine("Method{0}", str);

        }

    }

内置Attribute

 

自定义Attribute:

代码2:

[AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = false)]

    public class HelpAttribute : Attribute

    {

        public HelpAttribute(string str)

        {

            HelpStr = str;

        }

        public string Name { get; set; }

        public string HelpStr { get; set; }

    }

自定义Attribute

AttributeTargets.Class：作用目标只能是类.

AllowMultiple:是否可以在一个元素上多次作用特性.

Inherited:当目标被继承时,特性是否也继承.

 

反射获取类的Attribute信息:

代码3:

class Program

    {

        static void Main(string[] args)

        {

            var attrs = typeof(MyClass).GetCustomAttributes(false);

            for (int i = 0; i < attrs.Length; i++)

            {

                var attr = attrs[i] as HelpAttribute;

                if (attr != null) Console.WriteLine(attr.HelpStr + attr.Name);

            }

            Console.ReadLine();

        }

    }



    [Help("good", Name = " class")]

    class MyClass

    {



    }

反射获取特性信息