ConsoleApplication--控制台应用程序
首先创建基类：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks; namespace Attribute_Exercise
{
/// <summary>
/// 此处的注释不影响编译和运行，只是给开发者提供帮助
/// </summary>
//[some Attribute] e.g.
[Obsolete] //[Obsolete]、[Obsolete("")]、[Obsolete("",true/false)] Obsolete的构造函数 F12查看
[Serializable]
public class BasicClass
{
//基类属性、字段
public int ID { set; get; } public string Name { set; get; } } public class AClass:BasicClass
{ } public class BClass : BasicClass
{ } public class CClass : BasicClass
{ }
}
其次自定义一个Attribute：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks; namespace Attribute_Exercise
{
/// <summary>
/// 自定义一个Attribute：somename+Attribute
/// 使用时：[somename]
/// </summary>
public class CustomizedAttribute:Attribute
{
//以下是构造函数
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
{ }
}
在主入口中：
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)
{
//主要运用了继承的机制
BasicClass bc = new BasicClass() { ID=,Name="基类1"};
Console.WriteLine("基类ID：{0} ；基类类名：{1}",bc.ID,bc.Name);
Console.ReadLine();
}
}
}
先看看基类的效果:
下面进入主题--如何在不改变基类及其继承类的对象的情况下，仅仅通过声明Attribute，使得这些继承类具有不同的行为或者效果？
1.声明Attribute：在BasicClass.cs Line 23处增加 [Customized] ;
2.增加相应Attribute的方法：
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("当前类额外的Attribute：{0}",
customizedAttr.ToString().Substring(customizedAttr.ToString().IndexOf(".")+));
Console.WriteLine("+++++++++++++++++++++++++++++++++++++++++++++++++");
} }
}
}
3.在程序主入口调用方法：
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)
{
//主要运用了继承的机制
BasicClass bc = new BasicClass() { ID=,Name="基类1"};
Console.WriteLine("基类ID：{0} ；基类类名：{1}",bc.ID,bc.Name);
Console.WriteLine("*************************************************");
AttributeActivities.OutPut<AClass>(new AClass()
{
ID=,
Name="AClass"
});
Console.WriteLine("*************************************************");
AttributeActivities.OutPut<BClass>(new BClass()
{
ID = ,
Name = "BClass"
});
Console.WriteLine("*************************************************");
AttributeActivities.OutPut<CClass>(new CClass()
{
ID = ,
Name = "CClass"
}); Console.ReadLine();
}
}
}
结果截图：
是不是感觉很神奇呢？ 并没有对这个继承类做任何修改，只是多了个声明，然后附加相应的方法就实现了拥有不同Attribute的类具有不同的效果。
读者也可以自己扩展其它的方法试试哦。。。
补充：
Attribute里增加：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks; namespace Attribute_Exercise
{
/// <summary>
/// 自定义一个Attribute：somename+Attribute
/// 使用时：[somename]
/// </summary>
public class CustomizedAttribute:Attribute
{
//以下是构造函数
public CustomizedAttribute()
{
//空
} public CustomizedAttribute(string msg)
{ } public CustomizedAttribute(string msg, bool err)
{ } //字段
public string Msg;
public bool Err; //增加部分
//扩展方法
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
{ }
}
方法调用：
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("当前类额外的Attribute：{0}",
customizedAttr.ToString().Substring(customizedAttr.ToString().IndexOf(".")+));
Console.WriteLine("+++++++++++++++++++++++++++++++++++++++++++++++++");
//调用扩展方法
customizedAttr.DoSomeThing(t.Name);
} }
}
}
在继承类前声明Attribute：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks; namespace Attribute_Exercise
{
/// <summary>
/// 此处的注释不影响编译和运行，只是给开发者提供帮助
/// </summary>
//[some Attribute] e.g.
[Obsolete] //[Obsolete]、[Obsolete("")]、[Obsolete("",true/false)] Obsolete的构造函数 F12查看
[Serializable]
public class BasicClass
{
//基类属性、字段
public int ID { set; get; } public string Name { set; get; } }
//声明Attribute
[Customized]
public class AClass:BasicClass
{ }
//声明扩展Attribute的构造函数
[Customized("",,true)]
public class BClass : BasicClass
{ } public class CClass : BasicClass
{ }
}
结果：
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