重构版机房收费系统构建思路

重构机房收费系统已经一周了快，从最开始的毫无头绪，到现在的思路明晰，真是经过了各种煎熬啊。以下是我的包图：

重构版机房收费系统构建思路

这里用一个接口来解耦了B层和D层。这样B层和D层互相就没有了直接联系。工厂用反射和配置文件来访问数据库，这样换数据库也不用改D层代码，只要把字符串“SQLserver”改成其他数据库的名字如：“access”。就可以访问access数据库了。

以一个注册新学生为例：

ChargeFactory中的代码：

'生产一个istudent接口。用到了反射和配置文件，这里U层的APP.config已经配置好。

Imports System.Reflection'引入反射Imports System.ConfigurationImports [Interface]Public Class studentFactory    Private Shared ReadOnly AssemblyName As String = "ChargeDAL"    Private Shared ReadOnly db As String = ConfigurationManager.AppSettings("DB")    Public Function CreateIStudent() As IStudent        Dim istudent As [Interface].IStudent        Dim className As String = "ChargeDAL" + "." + db + "StudentD"        istudent = CType(Assembly.Load(AssemblyName).CreateInstance(className), IStudent)        Return istudent    End FunctionEnd Class

Interface中的代码：

Public Interface IStudent

    Function Register(enstudent As ChargeEntity.Student) As Integer

End Interface

ChargeDAL中的代码：

Imports System.Data
Imports System.Data.SqlClient
Imports ChargeDAL.SQLHelper
Imports [Interface]
Public Class StudentD
    Implements [Interface].IStudent
'学生注册方法
    Public Function Register(enstudent As ChargeEntity.Student) As Integer Implements [Interface].IStudent.Register
        Dim strSQL As String
        Dim regSqlHelper As New ChargeDAL.SQLHelper '实例化一个SQLhelper
        Dim intReg As Integer
        strSQL = "insert into student(cardID,name,stuID,sex,department,grade,class,balance,state,remark) values (@CardID,@name,@stuID,@sex,@department,@grade,@class,@balance,@state,@remark)" '添加到数据库
        Dim sqlPara As SqlParameter() =
            {
                New SqlParameter("@CardID", enstudent.CardID),
                New SqlParameter("@balance", enstudent.Balance),
                New SqlParameter("@name", enstudent.Name),
                New SqlParameter("@stuID", enstudent.StuID),
                New SqlParameter("@sex", enstudent.Sex),
                New SqlParameter("@department", enstudent.Department),
                New SqlParameter("@grade", enstudent.Grade),
                New SqlParameter("@class", enstudent.ClassID),
                New SqlParameter("@state", enstudent.State),
                New SqlParameter("@remark", enstudent.Remark)
            }
        intReg = regSqlHelper.ParaDataManager(strSQL, CommandType.Text, sqlPara) '调用sqlhelper的增删改（有参数）方法，返回一个integer，若是0则添加失败，1则是添加成功了1条记录
        Return intReg
    End Function
End Class

ChargeBLL层的代码：

'判断是否添加成功
Public Class RegisterManager
    Public Function Register(enstudent As ChargeEntity.Student) As Boolean
        Dim studentFactory As New ChargeFactory.studentFactory'定义一个新工厂
        Dim istudent As [Interface].IStudent'定义一个接口
        istudent = studentFactory.CreateIStudent()'实现工厂的创建接口方法，赋值于istudent

        Dim intReg As Integer
        intReg = istudent.Register(enstudent)'实现接口的Register方法，避免和D层打交道
        If intReg = 0 Then
            Return False
        Else
            Return True
        End If

    End Function
End Class

ChargeUI层的代码：

Public Class frmRegisterUI

    Private Sub btnOk_Click(sender As Object, e As EventArgs) Handles btnOk.Click
        Dim enstudent As New ChargeEntity.Student '定义一个实体
        Dim regManager As New ChargeBLL.RegisterManager

        enstudent.CardID = Trim(txtCardID.Text)
        enstudent.StuID = Trim(txtStuID.Text)
        enstudent.Name = Trim(txtName.Text)
        enstudent.Balance = CDec(Trim(txtBalance.Text))
        enstudent.Sex = cmbSex.Text
        enstudent.Department = Trim(txtDepartment.Text)
        enstudent.Grade = Trim(txtGrade.Text)
        enstudent.ClassID = Trim(txtClassID.Text)
        enstudent.Remark = Trim(txtRemark.Text)
        enstudent.State = Trim(txtState.Text)
        txtShowBalance.Text = txtBalance.Text

        If regManager.Register(enstudent) = False Then '通过B层的判断，反馈注册信息。
            MsgBox("注册失败")
        Else
            MsgBox("注册成功")
        End If
    End Sub
End Class

这样就实现了注册功能，外观模式还没加上去，就先不写了。

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重构版机房收费系统构建思路

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