三层 之 充值

在三层的地方也炖了不少时间了，再炖就烂了，找好了时机，趁大家不注意，总结一下：

从上面的这幅导图中，就可以看到，由U层（表示层） 引用 B层（逻辑判断层）和 Entity（实体“层”），由 B层 引用 D层和实体层，由D层引用实体层，也就是

只能单向引用，不可反复

下面，还是由实例来说明耕层之间的关系：

充值之界面：

                     

充值之U层：

<pre name="code" class="vb">Public Class Form1

    Private Sub btnOK_Click(sender As Object, e As EventArgs) Handles btnOK.Click
        Try
            Dim eUser2 As New EntityRecharge.RechargeInfo
            Dim eUser3 As EntityRecharge.RechargeInfo

            eUser2.IDcard = Trim(txtIDcard.Text)
            eUser2.AddCash = Trim(txtAddCash.Text)

            Dim mgr As New RechargeBLL.RechargeManager
            eUser3 = mgr.RechargeSc(eUser2)
        Catch ex As Exception
            MessageBox.Show(ex.Message.ToString())
        End Try
        

    End Sub

    Private Sub btnCancel_Click(sender As Object, e As EventArgs) Handles btnCancel.Click
        Me.Close()
    End Sub
End Class

充值之B层：

<pre name="code" class="vb">Public Class RechargeManager
    Public Function RechargeSc(ByVal User As RechargeInfo) As EntityRecharge.RechargeInfo
        Dim rDAO As New RechargeDAL.RechargeDAO
        Dim eUser1 As Boolean

        eUser1 = rDAO.SelectUser(User)        '寻找卡号
        If eUser1 = False Then                '返回FALSE 代表  查找失败，也就是卡号未注册
            Throw New Exception("卡号不存在，充值失败")
        Else
            eUser1 = rDAO.UpdateCash(User)     '查找成功，执行充值操作
            If eUser1 = True Then
                MsgBox("充值成功")
            Else
                Throw New Exception("充值失败")
            End If
        End If
        Return User

    End Function
End Class

充值之D层：

Public Class RechargeDAO
    Public conn As New SqlConnection("server=.;database=Login;user id=sa;password=li")

    Public Function SelectUser(ByVal User As RechargeInfo) As Boolean
        Dim eUser As New EntityRecharge.RechargeInfo
        Dim reader As SqlDataReader
        'Dim intNum1 As Integer
        Dim sql As String = "SELECT * FROM Recharge WHERE IDcard=@IDcard"
        Dim cmd As New SqlCommand(sql, conn)


        cmd.CommandText = sql                     '获取SQL语句的具体内容
        cmd.CommandType = CommandType.Text         '获取上述SQL语句的具体类型，在此为Select
        cmd.Parameters.Add(New SqlParameter("@IDcard", User.IDcard)) '若用成eUser.UserName则会出现参数未传递的错误提示
        'MsgBox(conn.State)
        conn.Open()
        reader = cmd.ExecuteReader
        While reader.Read
            eUser.IDcard = reader.GetInt32(0)
        End While
        conn.Close()
        If eUser.IDcard = Nothing Then
            Return False
        Else
            Return True
        End If
    End Function

    Public Function UpdateCash(ByVal User As RechargeInfo) As Boolean
        Dim intNum As Integer
        Dim eUser As New EntityRecharge.RechargeInfo
        Dim sql As String = "INSERT INTO Recharge (IDcard,AddCash,Cash) VALUES (@IDcard,@AddCash,@Cash)"
        Dim cmd As New SqlCommand(sql, conn)

        cmd.CommandText = sql
        cmd.CommandType = CommandType.Text
        cmd.Parameters.Add(New SqlParameter("@IDcard", User.IDcard))
        cmd.Parameters.Add(New SqlParameter("@AddCash", User.AddCash))
        cmd.Parameters.Add(New SqlParameter("@Cash", 11 + User.AddCash))
        conn.Open()                   '打开连接
        intNum = cmd.ExecuteNonQuery()     '返回 受影响行数
        conn.Close()        '关闭连接
        If intNum = 1 Then
            Return True
        Else
            Return False       '返回 处理结果
        End If

    End Function

End Class

Entity层：

<pre name="code" class="vb">Public Class RechargeInfo
    Dim _idcard As Integer
    Dim _cash As Integer
    Dim _addcash As Integer

    Public Property IDcard As Integer          '设置IDcard属性
        Get
            Return _idcard
        End Get
        Set(value As Integer)
            _idcard = value
        End Set
    End Property
    Public Property AddCash As Integer          '设置AddCash属性
        Get
            Return _addcash
        End Get
        Set(value As Integer)
            _addcash = value
        End Set
    End Property
    Public Property Cash As Integer             '设置Cash属性
        Get
            Return _cash
        End Get
        Set(value As Integer)
            _cash = value
        End Set
    End Property
End Class

其实吧，这篇和登录那片是差不多的，不一样的地方是，这次在查询的时候，我都用的是Boolean返回值，也就是说，我不需要你查询的数据，我只需要你查询的结果代表的意义，有没有这条数据，有就直接告诉我有，没有就直接告诉我没有，不需要再去比对