經過聲明Attribute屬性改變不一樣類的輸出效果

時間 2019-11-10

原文原文鏈接

ConsoleApplication--控制檯應用程序ide

首先建立基類：函數

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

namespace Attribute_Exercise
{
    /// <summary>
    /// 此處的註釋不影響編譯和運行，只是給開發者提供幫助
    /// </summary>  
    //[some Attribute]  e.g.
    [Obsolete] //[Obsolete]、[Obsolete("")]、[Obsolete("",true/false)]  Obsolete的構造函數 F12查看 
    [Serializable]
    public class BasicClass
    {
        //基類屬性、字段
        public int ID { set; get; }

        public string Name { set; get; }

    }
            
    public class AClass:BasicClass
    {
    
    }

    public class BClass : BasicClass
    { 
    
    }

    public class CClass : BasicClass
    { 
    
    }
}

View Code

其次自定義一個Attribute：this

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

namespace Attribute_Exercise
{
    /// <summary>
    /// 自定義一個Attribute：somename+Attribute
    /// 使用時：[somename]
    /// </summary>
    public class CustomizedAttribute:Attribute
    {
        //如下是構造函數
        public CustomizedAttribute()
        { 
           //空
        }

        public CustomizedAttribute(string msg)
        { 
        
        }

        public CustomizedAttribute(string msg, bool err)
        { 
            
        }

        //字段
        public string Msg;
        public bool Err;

               



    }

    public class esleCusomizedAttribute : Attribute
    { 
    
    }
}

View Code

在主入口中：spa

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

namespace Attribute_Exercise
{
    class Program
    {
        static void Main(string[] args)
        {
            //主要運用了繼承的機制
            BasicClass bc = new BasicClass() { ID=1,Name="基類1"};
            Console.WriteLine("基類ID：{0}  ；基類類名：{1}",bc.ID,bc.Name);
            Console.ReadLine();
        }
    }
}

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先看看基類的效果:
3d

下面進入主題--如何在不改變基類及其繼承類的對象的狀況下，僅僅經過聲明Attribute，使得這些繼承類具備不一樣的行爲或者效果？code

1.聲明Attribute：在BasicClass.cs Line 23處增長 [Customized] ;對象

2.增長相應Attribute的方法：blog

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;//反射
using System.Text;
using System.Threading.Tasks;

namespace Attribute_Exercise
{
    public class AttributeActivities
    {
        public static void OutPut<T>(T t) where T : BasicClass
        {
            Type type=t.GetType();
            Attribute attribute = type.GetCustomAttribute(typeof(CustomizedAttribute));//注意  using System.Reflection;
            if (attribute != null && attribute is CustomizedAttribute)
            {
                CustomizedAttribute customizedAttr = attribute as CustomizedAttribute;

                Console.WriteLine("當前類額外的Attribute：{0}",
                    customizedAttr.ToString().Substring(customizedAttr.ToString().IndexOf(".")+1));
                Console.WriteLine("+++++++++++++++++++++++++++++++++++++++++++++++++");
            }
            
        }
    }
}

View Code

3.在程序主入口調用方法：繼承

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

namespace Attribute_Exercise
{
    class Program
    {
        static void Main(string[] args)
        {
            //主要運用了繼承的機制
            BasicClass bc = new BasicClass() { ID=1,Name="基類1"};
            Console.WriteLine("基類ID：{0}  ；基類類名：{1}",bc.ID,bc.Name);
            Console.WriteLine("*************************************************");
            AttributeActivities.OutPut<AClass>(new AClass()
            {
                ID=2,
                Name="AClass"                
            });
            Console.WriteLine("*************************************************");
            AttributeActivities.OutPut<BClass>(new BClass()
            {
                ID = 3,
                Name = "BClass"
            });
            Console.WriteLine("*************************************************");
            AttributeActivities.OutPut<CClass>(new CClass()
            {
                ID = 4,
                Name = "CClass"
            });

            Console.ReadLine();
        }
    }
}

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結果截圖：
ci

是否是感受很神奇呢？並無對這個繼承類作任何修改，只是多了個聲明，而後附加相應的方法就實現了擁有不一樣Attribute的類具備不一樣的效果。

讀者也能夠本身擴展其它的方法試試哦。。。

補充：

Attribute裏增長：

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

namespace Attribute_Exercise
{
    /// <summary>
    /// 自定義一個Attribute：somename+Attribute
    /// 使用時：[somename]
    /// </summary>
    public class CustomizedAttribute:Attribute
    {
        //如下是構造函數
        public CustomizedAttribute()
        { 
           //空
        }

        public CustomizedAttribute(string msg)
        {
            
        }

        public CustomizedAttribute(string msg, bool err)
        { 
            
        }

        //字段
        public string Msg;
        public bool Err;

        //增長部分
        //擴展方法
        public int Number;
        public void DoSomeThing(string msg)
        {
            if (Err)
            {
                Console.WriteLine("{0}--{1}",msg,DateTime.Now);
            }
        }
        public CustomizedAttribute(string msg, int number, bool err) 
        {
            this.Msg = msg;
            this.Number = number;
            this.Err = err;
        }




               
    }

    public class esleCusomizedAttribute : Attribute
    { 
    
    }
}

View Code

方法調用：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;//反射
using System.Text;
using System.Threading.Tasks;

namespace Attribute_Exercise
{
    public class AttributeActivities
    {
        public static void OutPut<T>(T t) where T : BasicClass
        {
            Type type=t.GetType();
            Attribute attribute = type.GetCustomAttribute(typeof(CustomizedAttribute));//注意  using System.Reflection;
            if (attribute != null && attribute is CustomizedAttribute)
            {
                CustomizedAttribute customizedAttr = attribute as CustomizedAttribute;

                Console.WriteLine("當前類額外的Attribute：{0}",
                    customizedAttr.ToString().Substring(customizedAttr.ToString().IndexOf(".")+1));
                Console.WriteLine("+++++++++++++++++++++++++++++++++++++++++++++++++");
                //調用擴展方法
                customizedAttr.DoSomeThing(t.Name);
            }
            
        }
    }
}

View Code

在繼承類前聲明Attribute：

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

namespace Attribute_Exercise
{
    /// <summary>
    /// 此處的註釋不影響編譯和運行，只是給開發者提供幫助
    /// </summary>  
    //[some Attribute]  e.g.
    [Obsolete] //[Obsolete]、[Obsolete("")]、[Obsolete("",true/false)]  Obsolete的構造函數 F12查看 
    [Serializable]   
    public class BasicClass
    {
        //基類屬性、字段
        public int ID { set; get; }
       
        public string Name { set; get; }

    }
     //聲明Attribute
    [Customized]   
    public class AClass:BasicClass
    {
    
    }
    //聲明擴展Attribute的構造函數
    [Customized("",1,true)]
    public class BClass : BasicClass
    { 
    
    }

    public class CClass : BasicClass
    { 
    
    }
}