(200-06-18) VB.NET 類別規劃

2010-06-18

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VB.NET

摘要:(200-06-18) VB.NET 類別規劃

Webmod06.rarClass 類別

具有分類的意義

使用 "特徵" (Attribute) 分類

不使用功能分類Method * Method 程序 ( 行為或功能 )

如用功能分會有可能沒辦法在集合內 (如：電話(接,聽) 網路電話[不等於電話])

Method "飛"<--- 抽象描述(超人飛,鳥飛)

例: Employee(員工)[原型]--->工程師 , 業務員

類別


Namespace Domain.IT
    'public Modifier修飾詞-可見度
    '編譯產生父類別為System.Object
    Public Class Employee
        '類別層級變數(Data Field)
        Private _id As String
        Private _name As String
        '實現封裝特性(private 私用 -可見度限這一個類別內)
        Private _salary As Decimal
        Private _birthDate As DateTime
        Private _sex As String
        ' 編譯產生預設建構子 空參數


        '屬性存取(程序)
        Public Property Salary() As Decimal
            Get
                Return _salary
            End Get
            Set(ByVal value As Decimal)
                If (value > 0) Then
                    _salary = value
                End If
            End Set
        End Property

        Public Property Id() As String
            Get
                Return Me._id
            End Get
            Set(ByVal value As String)
                Me._id = value

            End Set
        End Property

        Public Property Name() As String
            Get
                Return Me._name
            End Get
            Set(ByVal value As String)
                Me._name = value
            End Set
        End Property

        Public Property BirthDate() As DateTime
            Get
                Return Me._birthDate
            End Get
            Set(ByVal value As DateTime)
                If (value <= System.DateTime.Now) Then
                    Me._birthDate = value
                End If

            End Set
        End Property

        Public Property Sex() As String
            Get
                Return Me._sex
            End Get
            Set(ByVal value As String)
                Me._sex = value
            End Set
        End Property
    End Class
End Namespace

主程式


Imports mod06.Domain.IT
Module TestEmployee
    '主程式
    Public Sub Main()
        '定義區域變數
        Dim emp As Employee = Nothing
        '建構物件Cosntructor
        '= 將起始位址給 emp
        emp = New Employee() '使用預設建構子(沒有寫編譯產生)
        Dim emp2 As Employee = Nothing
        emp2 = emp  'emp將位址複製一份給emp2 emp and emp2參考同一個員工物件

        emp.id = "0001" '字串物件位址給id儲存
        emp.name = "'eric"
        ''程序性思考(非物件思考)
        'Dim s As Decimal = -10000
        ''If s > 0 Then
        ''    emp.salary = s
        ''End If
        'Setter 
        emp.Salary = 10000
        '屬性getter
        Dim r As Decimal = emp.Salary
        System.Console.WriteLine(r.ToString())

        '呼叫員工繼承的Object功能
        System.Console.WriteLine(emp.ToString())

    End Sub
End Module

補充：類別層級變數一定有預設值

屬性 As 資料表的欄位

Property (屬性) 未用使不暫空間等到使用時才動態載入 (Later Binding)

屬性 As 資料表欄位


Partial Class _Default
    Inherits System.Web.UI.Page
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        '陣列
        Dim emp(3) As Employee
        emp(0) = New Employee() With {.Id = "00001", .Name = "eric", .Salary = 10000, .Sex = "男性", .BirthDate = New DateTime(2000, 1, 1)}
        emp(1) = New Employee() With {.Id = "00002", .Name = "linda", .Salary = 10000, .Sex = "女性", .BirthDate = New DateTime(2000, 1, 1)}
        emp(2) = New Employee() With {.Id = "00003", .Name = "barry", .Salary = 10000, .Sex = "男性", .BirthDate = New DateTime(2000, 1, 1)}
        emp(3) = New Employee() With {.Id = "00004", .Name = "Candy", .Salary = 10000, .Sex = "女性", .BirthDate = New DateTime(2000, 1, 1)}
        '資料繫結
        Me.GridView1.DataSource = emp
        Me.GridView1.DataBind()
    End Sub
End Class

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