ASP中的类：踏上继承与多态性的奇妙征途

1. 继承

继承是指从现有类创建新类。子类继承了父类的所有成员（属性和方法），并且可以添加自己的新成员。继承允许代码重用，因为子类可以复用父类中的代码。

演示代码：

Class Animal
    Public Property Name As String
    Public Sub MakeSound()
        Console.WriteLine("Animal makes sound")
    End Sub
End Class

Class Dog Inherits Animal
    Public Property Breed As String
    Public Overrides Sub MakeSound()
        Console.WriteLine("Dog barks")
    End Sub
End Class

Dim animal As New Animal()
animal.Name = "Animal"
animal.MakeSound()

Dim dog As New Dog()
dog.Name = "Dog"
dog.Breed = "Golden Retriever"
dog.MakeSound()

输出：

Animal makes sound
Dog barks

2. 多态性

多态性是指子类可以覆盖父类的方法。当调用父类的方法时，实际调用的方法取决于运行时对象的类型。这允许子类提供父类方法的特定实现。

演示代码：

Class Animal
    Public Property Name As String
    Public Virtual Sub MakeSound()
        Console.WriteLine("Animal makes sound")
    End Sub
End Class

Class Dog Inherits Animal
    Public Property Breed As String
    Public Overrides Sub MakeSound()
        Console.WriteLine("Dog barks")
    End Sub
End Class

Class Cat Inherits Animal
    Public Property Species As String
    Public Overrides Sub MakeSound()
        Console.WriteLine("Cat meows")
    End Sub
End Class

Dim animals As New List(Of Animal)
animals.Add(New Dog() With {.Name = "Dog", .Breed = "Golden Retriever"})
animals.Add(New Cat() With {.Name = "Cat", .Species = "Siamese"})

For Each animal In animals
    animal.MakeSound()
Next

输出：

Dog barks
Cat meows

ASP中的类以及继承和多态特性为开发人员提供了强大的工具。通过这些特性，开发人员可以轻松构建可重用、灵活且可扩展的应用程序。