机房收费系统重构（五）—登陆窗口完整版

     在上上篇。《机房收费系统重构（3）》。中主要是介绍了自己关于DAL层，工厂层。以及接口层，还有实体层的理解。可是好多读者再问我。你的代码呢，我在这解释一下。就是我仅仅是写出关于那几部分的理解，并没有写贴出代码让大家研究的。可是不能顺应民心的文章不是好文章，所以我在这篇文章中，将机房收费登录中七层中全部的代码，贴出来供大家拍砖斧正。还有最后我在谈谈针对BLL层和外观层的理解。

     首先我所说的七层是针对UI层，外观层，BLL层，DAL层，工厂层，实体层，接口层七层组成。

     实现登录窗口，要明确。先要查询用户是否存在，然后将登录信息写入数据库，这两个主要步骤。

首先来看看我数据库中用到的两个表：

    这样能方便读者更easy理解后面的代码：

    一.首先看看实体层的代码吧

（1）用户表实体层：

Public Class MO_Login
  
    Private _userID As String
    Private _level As String
    Private _password As String
    Private _userName As String
    Private _computer As String


    Public Shared UserHead As String  ' 设置全局变量
    Public Shared UserLevel As String

    Public Property UserID() As String
        Get
            Return _userID
        End Get
        Set(value As String)
            _userID = value
        End Set
    End Property
    Public Property PassWord() As String
        Get
            Return _password
        End Get
        Set(value As String)
            _password = value
        End Set
    End Property
    Public Property level() As String
        Get
            Return _level
        End Get
        Set(value As String)
            _level = value
        End Set
    End Property
    Public Property UserName() As String
        Get
            Return _userName
        End Get
        Set(value As String)
            _userName = value
        End Set
    End Property
    Public Property Computer() As String
        Get
            Return _computer
        End Get
        Set(value As String)
            _computer = value
        End Set
    End Property
End Class

Public Class MO_Worklog
    Private _userID As String
    Private _level As String
    Private _loginDataTime As String
    Private _computer As String
    Private _status As String

    Public Shared Property Login_DataTime As String


    Public Property UserID() As String
        Get
            Return _userID
        End Get
        Set(value As String)
            _userID = value
        End Set
    End Property
    Public Property level() As String
        Get
            Return _level
        End Get
        Set(value As String)
            _level = value
        End Set
    End Property
    Public Property LoginDataTime() As String
        Get
            Return _loginDataTime
        End Get
        Set(value As String)
            _loginDataTime = value
        End Set
    End Property
    Public Property Computer() As String
        Get
            Return _computer
        End Get
        Set(value As String)
            _computer = value
        End Set
    End Property
    Public Property Status() As String
        Get
            Return _status
        End Get
        Set(value As String)
            _status = value
        End Set
    End Property
End Class

Public Class frmLogin

    Private Sub btnOK_Click(sender As Object, e As EventArgs) Handles btnOK.Click
        Dim login As New Model.MO_Login
        Dim falogin As New Facade.FA_Login     '实例化过程

        Dim strResult As String

        login.UserID = txtUserName.Text        '赋值过程
        login.PassWord = txtPassWord.Text

        Model.MO_Login.UserHead = txtUserName.Text

        Dim worklog As New Model.MO_Worklog    '实例化工作记录
        worklog.LoginDataTime = Date.Now.ToString("yyyy-mm-dd hh:mm:ss")  '上机时间
        worklog.Status = "正在值班"                                       '工作状态
        worklog.UserID = Model.MO_Login.UserHead
        worklog.Computer = System.Net.Dns.GetHostName().ToString()        '本地计算机

        strResult = falogin.FLogin(login, worklog)                        '传參返回过程

        Select Case strResult                                             '推断过程
            Case "输入有误"
                MsgBox("输入有误。请又一次输入")
            Case "登录成功"
                MsgBox("登录成功")

                Model.MO_Worklog.Login_DataTime = worklog.LoginDataTime
                Me.Hide()
                'frmMain.Show()
        End Select

    End Sub

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

Imports BLL
Public Class FA_Login
    Public Function FLogin(ByVal user As Model.MO_Login, worklog As Model.MO_Worklog) As String
        Dim UserBLL As New BLL.BL_Login

        If UserBLL.IsnotNull(user, worklog) = False Then
            Return "输入有误"
        Else
            Return "登录成功"
        End If
    End Function
End Class

<pre name="code" class="vb">Imports IDAL
Public Class BL_Login
    Public Function IsnotNull(ByVal user As Model.MO_Login, ByVal worklog As Model.MO_Worklog) As Boolean
        Dim IUser As IDAL.ILogin                          '注意接口类型不能实例化。
        Dim factory As New Factory.LoginFactory           '实例化工厂
        Dim IWorklog As IDAL.IWorklog

        IUser = factory.CreateUserInfo()                  '工厂创建接口，DAL实现接口。BLL调用工厂
        IWorklog = factory.CreateWorklog()

        If IUser.User_Login(user).UserID = "" Then        '假设为空
            Return False                                  'Boolean值为false
        Else
            worklog.level = IUser.User_Login(user).level   '传參数。将查询到的用户类型传给worklog实体层。在后面的增删改中应用。

            If IWorklog.SaveWorkLog(worklog) Then          '假设查询到用户存在，就開始将登录信息写入数据库中。

                Return True
            End If
            Return True
        End If

    End Function
End Class

  五.工厂层代码：

Imports System.Reflection '加入反射的引用
Imports System.Configuration '加入配置文件的引用
Imports IDAL
Public Class LoginFactory
    '利用反射+配置文件+抽象工厂
    Dim strDB As String = System.Configuration.ConfigurationSettings.AppSettings("strSqlConnection")
    '表示读取配置文件。假设配置文件里是SQLserver数据库就訪问，假设是别的就放訪问别的，不须要更改代码
    'Dim strQueryWorkLog As String = System.Configuration.ConfigurationSettings.AppSettings("strSqlConnection")
    '创建用户表工厂
    Public Function CreateUserInfo() As ILogin
        Return CType(Assembly.Load("DAL").CreateInstance("DAL" & "." & "DA_Login"), ILogin)
    End Function
    Public Function CreateWorklog() As IWorklog
        Return CType(Assembly.Load("DAL").CreateInstance("DAL" & "." & "DA_Worklog"), IWorklog)
    End Function

End Class

（1）用户查询接口

Public Interface ILogin
    Function User_Login(ByVal user As Model.MO_Login) As Model.MO_Login
End Interface

Public Interface IWorklog
    Function SaveWorkLog(ByVal worklog As Model.MO_Worklog) As Boolean
End Interface

（1）用户查询DAL

Imports System.Data.SqlClient
Imports System.Data
Imports IDAL
Public Class DA_Login : Implements IDAL.ILogin

    Public Function User_Login(user As Model.MO_Login) As Model.MO_Login Implements IDAL.ILogin.User_Login
        Dim sqlparams As SqlParameter() = {New SqlParameter("@UserID", user.UserID), New SqlParameter("@Password", user.PassWord)} '传递參数过程
        Dim cmdText As String = "select * from T_UserInfo where UserName =@UserID and PassWord =@Password"                         '查询数据库
        Dim aUser As New Model.MO_Login  '实例化过程

        Dim helper As New SqlHelper
        Dim cmdType As CommandType = New CommandType()
        cmdType = CommandType.Text       '定义命令类型为存储过程
        Dim table As DataTable           '实例化一个过程
        '在这里想解释一个，因为函数返回參数是实体层。可是这里定义的table是一个Datable类型。所以系统无法进行转换。
所以我定义了一个aUser进行中转。
        table = helper.ExecuteQuery(cmdText, cmdType, sqlparams) '定义返回值
        If table.Rows.Count <> 0 Then
            aUser.UserID = table.Rows(0).Item("UserID")
            aUser.PassWord = table.Rows(0).Item("PassWord")
            aUser.level = table.Rows(0).Item("level")
            aUser.UserName = table.Rows(0).Item("UserName")
        End If
        Return aUser
    End Function
End Class

Imports System.Data.SqlClient
Imports System.Data
Imports IDAL
Public Class DA_Worklog : Implements IDAL.IWorklog
    Public Function SaveWorkLog(worklog As Model.MO_Worklog) As Boolean Implements IWorklog.SaveWorkLog
        Dim strText As String = "INSERT INTO T_WorkLog(UserID,level,LoginDateTime,Computer,Status)VALUES (@UserID,@level,@LoginDateTime,@Computer,@Status)"
        Dim sqlparams As SqlParameter() = {New SqlParameter("@UserID", worklog.UserID), New SqlParameter("@level", worklog.level), New SqlParameter("@LoginDateTime", worklog.LoginDataTime), New SqlParameter("@Computer", worklog.Computer), New SqlParameter("@Status", worklog.Status)}
        Dim cmdType As CommandType = CommandType.Text
        Dim helper As New SqlHelper
        Return helper.ExecuteNonQuery(strText, cmdType, sqlparams)
    End Function
End Class

    最后说一下关于BLL和外观层的理解吧。从代码看。仿佛感觉外观层没有什么作用，是的，关于登录窗口小功能的实现，没有太大的必要用外观层，可是以后要敲一个庞大的窗口时，我们须要将U层和B层解耦，那么外观层的作用就彰显出来了。关于BLL和外观事实上没有什么想说的。最想说的是数据类型的转换，由于层与层之间传递參数和返回參数的过程须要用到相同类型的数据，可是将数据类型都设置为Datatable和string或者实体类型是不可能。希望大家在今后写程序过程中注意就能够了。

   本片文章代码较多。希望大家拍砖斧正。。