C#特性学习笔记二

实例探讨:

自定义了一个特性类：

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[AttributeUsage(AttributeTargets.Class|AttributeTargets.Method)]

class WahAttribute:System.Attribute

{

private string description;

public string Description

{

get { return description; }

set { description = value; }

}

private string author;

public string Author

{

get { return author; }

set { author = value; }

}

public WahAttribute(string desc)

{

this.description = desc;

}

}

[c-sharp] view plaincopyprint?

namespace attributeDemo

{

public class Teacher

{

private string name;

public string Name

{

get { return name; }

set { name = value; }

}

private int age;

public int Age

{

get { return age; }

set { age = value; }

}

private string sex;

public string Sex

{

get { return sex; }

set { sex = value; }

}

//只有用户名为wah的才可以调用此方法

[Wah("this is my attribute test", Author = "wah", Description = "test")]

public string getMessage()

{

return "好好学习，天天向上";

}

[Wah("this is with parameters test",Author="wanggaihui",Description="test with parameters")]

public int Test(int a,int b)

{

return a+b;

}

}

}

namespace attributeDemo
{
public class Teacher
{
private string name;

public string Name
{
get { return name; }
set { name = value; }
}
private int age;

public int Age
{
get { return age; }
set { age = value; }
}
private string sex;

public string Sex
{
get { return sex; }
set { sex = value; }
}
//只有用户名为wah的才可以调用此方法
[Wah("this is my attribute test", Author = "wah", Description = "test")]
public string getMessage()
{
return "好好学习，天天向上";
}
[Wah("this is with parameters test",Author="wanggaihui",Description="test with parameters")]
public int Test(int a,int b)
{
return a+b;
}
}
}

处理特性类：

[c-sharp] view plaincopyprint?

private void button_Click(object sender, EventArgs e)

{

//得到类型

Type type = typeof(Teacher);

//得到此类型所有方法

MethodInfo[] methods = type.GetMethods();

foreach (MethodInfo method in methods)

{

//得到此方法的所有特性

object[] attributes = method.GetCustomAttributes(false);

foreach (object o in attributes)

{

//判断是否是自己定义的特性

if (o.GetType() == typeof(WahAttribute))

{

//强转取得值

WahAttribute waha = (WahAttribute)o;

this.listBox1.Items.Add("author=" + waha.Author);

this.listBox1.Items.Add("description=" + waha.Description);

}

}

}

}

private void button_Click(object sender, EventArgs e)
{
//得到类型
Type type = typeof(Teacher);
//得到此类型所有方法
MethodInfo[] methods = type.GetMethods();
foreach (MethodInfo method in methods)
{
//得到此方法的所有特性
object[] attributes = method.GetCustomAttributes(false);
foreach (object o in attributes)
{
//判断是否是自己定义的特性
if (o.GetType() == typeof(WahAttribute))
{
//强转取得值
WahAttribute waha = (WahAttribute)o;
this.listBox1.Items.Add("author=" + waha.Author);
this.listBox1.Items.Add("description=" + waha.Description);
}
}
}
}

C#特性可以应用于各种类型和成员。加在类前面的是类特性，加在方法前面的是方法特性。无论他们被用在哪里，无论他们之间有什么区别，特性的最主要的目的就是自描述。并且因为特性是可以由自己定制的，而不仅仅局限于.net提供的那几个现成的，因此给C#程序开发带来了很大的灵活性。