vb.net - 一桌多班

Question

假设我有一个这样的数据库结构：

create table Product(id int not null identity,Name varchar(30))
INSERT INTO Product VALUES ('ProductA')
INSERT INTO Product VALUES ('ProductB')

和这样的类结构：

    Imports System.Data.SqlClient

Public Class Product

    Protected ProductName As String

    Public Overridable Sub Display()

    End Sub

End Class

Public Class ProductA
    Inherits Product

    Public Sub New(ByVal product As String)
        ProductName = product
    End Sub

    Public Overrides Sub Display()
        'Specific logic to display product A
    End Sub

End Class

Public Class ProductB
    Inherits Product

    Public Sub New(ByVal product As String)
        ProductName = product
    End Sub

    Public Overrides Sub Display()
        'Specific logic to display product B
    End Sub

End Class

Public Class Form1

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim p1 As Product
        Dim p2 As Product

        p1 = New ProductA("ProductA")
        p2 = New ProductB("ProductB")
        p1.Display()
        p2.Display()
    End Sub
End Class

有一个属性（产品）可以标识该类与哪个产品相关。这对我来说看起来不正确。有没有更好的建模方法？这类似于 NHibernate 的鉴别器概念（在这种情况下我没有使用 NHibernate）。

Answer 1

随着您的最新更改，您应该将构造函数移动到基类。除此之外，设计还不错。

Public Class Product

    Protected ProductName As String

    Public Sub New(ByVal product As String)
        ProductName = product
    End Sub

    Public Overridable Sub Display()

    End Sub

End Class

Public Class ProductA
    Inherits Product

    Public Overrides Sub Display()
        'Specific logic to display product A
    End Sub

End Class

此外，在您的声明中，您可以使用继承的类：

Dim p1 As ProductA
Dim p2 As ProductB