? ? ?在上上篇。《機房收費系統(tǒng)重構(gòu)（3）》。中主要是介紹了自己關(guān)于DAL層，工廠層。以及接口層，還有實體層的理解。可是好多讀者再問我。你的代碼呢，我在這解釋一下。就是我僅僅是寫出關(guān)于那幾部分的理解，并沒有寫貼出代碼讓大家研究的。可是不能順應(yīng)民心的文章不是好文章，所以我在這篇文章中，將機房收費登錄中七層中全部的代碼，貼出來供大家拍磚斧正。還有最后我在談?wù)勧槍LL層和外觀層的理解。

? ? ?首先我所說的七層是針對UI層，外觀層，BLL層，DAL層，工廠層，實體層，接口層七層組成。

? ? ?實現(xiàn)登錄窗口，要明確。先要查詢用戶是否存在，然后將登錄信息寫入數(shù)據(jù)庫，這兩個主要步驟。

首先來看看我數(shù)據(jù)庫中用到的兩個表：

??

? ? 這樣能方便讀者更easy理解后面的代碼：

? ? 一.首先看看實體層的代碼吧

（1）用戶表實體層：

Public Class MO_LoginPrivate _userID As StringPrivate _level As StringPrivate _password As StringPrivate _userName As StringPrivate _computer As StringPublic Shared UserHead As String ' 設(shè)置全局變量Public Shared UserLevel As StringPublic Property UserID() As StringGetReturn _userIDEnd GetSet(value As String)_userID = valueEnd SetEnd PropertyPublic Property PassWord() As StringGetReturn _passwordEnd GetSet(value As String)_password = valueEnd SetEnd PropertyPublic Property level() As StringGetReturn _levelEnd GetSet(value As String)_level = valueEnd SetEnd PropertyPublic Property UserName() As StringGetReturn _userNameEnd GetSet(value As String)_userName = valueEnd SetEnd PropertyPublic Property Computer() As StringGetReturn _computerEnd GetSet(value As String)_computer = valueEnd SetEnd Property End Class（2）工作記錄實體層：

Public Class MO_WorklogPrivate _userID As StringPrivate _level As StringPrivate _loginDataTime As StringPrivate _computer As StringPrivate _status As StringPublic Shared Property Login_DataTime As StringPublic Property UserID() As StringGetReturn _userIDEnd GetSet(value As String)_userID = valueEnd SetEnd PropertyPublic Property level() As StringGetReturn _levelEnd GetSet(value As String)_level = valueEnd SetEnd PropertyPublic Property LoginDataTime() As StringGetReturn _loginDataTimeEnd GetSet(value As String)_loginDataTime = valueEnd SetEnd PropertyPublic Property Computer() As StringGetReturn _computerEnd GetSet(value As String)_computer = valueEnd SetEnd PropertyPublic Property Status() As StringGetReturn _statusEnd GetSet(value As String)_status = valueEnd SetEnd Property End Class? ?二.接著來看看UI層的吧：

Public Class frmLoginPrivate Sub btnOK_Click(sender As Object, e As EventArgs) Handles btnOK.ClickDim login As New Model.MO_LoginDim falogin As New Facade.FA_Login '實例化過程Dim strResult As Stringlogin.UserID = txtUserName.Text '賦值過程login.PassWord = txtPassWord.TextModel.MO_Login.UserHead = txtUserName.TextDim worklog As New Model.MO_Worklog '實例化工作記錄worklog.LoginDataTime = Date.Now.ToString("yyyy-mm-dd hh:mm:ss") '上機時間worklog.Status = "正在值班" '工作狀態(tài)worklog.UserID = Model.MO_Login.UserHeadworklog.Computer = System.Net.Dns.GetHostName().ToString() '本地計算機strResult = falogin.FLogin(login, worklog) '傳參返回過程Select Case strResult '推斷過程Case "輸入有誤"MsgBox("輸入有誤。請又一次輸入")Case "登錄成功"MsgBox("登錄成功")Model.MO_Worklog.Login_DataTime = worklog.LoginDataTimeMe.Hide()'frmMain.Show()End SelectEnd SubPrivate Sub btnCancel_Click(sender As Object, e As EventArgs) Handles btnCancel.ClickEndEnd Sub End Class ? ?三.外觀層代碼：

Imports BLL Public Class FA_LoginPublic Function FLogin(ByVal user As Model.MO_Login, worklog As Model.MO_Worklog) As StringDim UserBLL As New BLL.BL_LoginIf UserBLL.IsnotNull(user, worklog) = False ThenReturn "輸入有誤"ElseReturn "登錄成功"End IfEnd Function End Class ? ?四.BLL層代碼：<pre name="code" class="vb">Imports IDAL Public Class BL_LoginPublic Function IsnotNull(ByVal user As Model.MO_Login, ByVal worklog As Model.MO_Worklog) As BooleanDim IUser As IDAL.ILogin '注意接口類型不能實例化。Dim factory As New Factory.LoginFactory '實例化工廠Dim IWorklog As IDAL.IWorklogIUser = factory.CreateUserInfo() '工廠創(chuàng)建接口，DAL實現(xiàn)接口。BLL調(diào)用工廠IWorklog = factory.CreateWorklog()If IUser.User_Login(user).UserID = "" Then '假設(shè)為空Return False 'Boolean值為falseElseworklog.level = IUser.User_Login(user).level '傳參數(shù)。將查詢到的用戶類型傳給worklog實體層。在后面的增刪改中應(yīng)用。

If IWorklog.SaveWorkLog(worklog) Then '假設(shè)查詢到用戶存在，就開始將登錄信息寫入數(shù)據(jù)庫中。

Return True End If Return True End If End Function End Class

? 五.工廠層代碼：

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+抽象工廠Dim strDB As String = System.Configuration.ConfigurationSettings.AppSettings("strSqlConnection")'表示讀取配置文件。假設(shè)配置文件里是SQLserver數(shù)據(jù)庫就訪問，假設(shè)是別的就放訪問別的，不須要更改代碼'Dim strQueryWorkLog As String = System.Configuration.ConfigurationSettings.AppSettings("strSqlConnection")'創(chuàng)建用戶表工廠Public Function CreateUserInfo() As ILoginReturn CType(Assembly.Load("DAL").CreateInstance("DAL" & "." & "DA_Login"), ILogin)End FunctionPublic Function CreateWorklog() As IWorklogReturn CType(Assembly.Load("DAL").CreateInstance("DAL" & "." & "DA_Worklog"), IWorklog)End FunctionEnd Class? 六.接口層代碼：

（1）用戶查詢接口

Public Interface ILoginFunction User_Login(ByVal user As Model.MO_Login) As Model.MO_Login End Interface（2）將操作記錄寫入數(shù)據(jù)庫代碼：

Public Interface IWorklogFunction SaveWorkLog(ByVal worklog As Model.MO_Worklog) As Boolean End Interface? 七.最后是DAL層代碼：

（1）用戶查詢DAL

Imports System.Data.SqlClient Imports System.Data Imports IDAL Public Class DA_Login : Implements IDAL.ILoginPublic Function User_Login(user As Model.MO_Login) As Model.MO_Login Implements IDAL.ILogin.User_LoginDim sqlparams As SqlParameter() = {New SqlParameter("@UserID", user.UserID), New SqlParameter("@Password", user.PassWord)} '傳遞參數(shù)過程Dim cmdText As String = "select * from T_UserInfo where UserName =@UserID and PassWord =@Password" '查詢數(shù)據(jù)庫Dim aUser As New Model.MO_Login '實例化過程Dim helper As New SqlHelperDim cmdType As CommandType = New CommandType()cmdType = CommandType.Text '定義命令類型為存儲過程Dim table As DataTable '實例化一個過程'在這里想解釋一個，因為函數(shù)返回參數(shù)是實體層。可是這里定義的table是一個Datable類型。所以系統(tǒng)無法進行轉(zhuǎn)換。

所以我定義了一個aUser進行中轉(zhuǎn)。 table = helper.ExecuteQuery(cmdText, cmdType, sqlparams) '定義返回值 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

（2）操作記錄寫入代碼DAL

Imports System.Data.SqlClient Imports System.Data Imports IDAL Public Class DA_Worklog : Implements IDAL.IWorklogPublic Function SaveWorkLog(worklog As Model.MO_Worklog) As Boolean Implements IWorklog.SaveWorkLogDim 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.TextDim helper As New SqlHelperReturn helper.ExecuteNonQuery(strText, cmdType, sqlparams)End Function End Class ? ? ??事實上這些代碼也不全。少了關(guān)于工廠反射的配置部分的內(nèi)容，還有就是SqlHelper。

SqlHelper，在我《機房收費重構(gòu)（4）》中有非常具體的介紹。

在這就不寫了。

? ? 最后說一下關(guān)于BLL和外觀層的理解吧。從代碼看。仿佛感覺外觀層沒有什么作用，是的，關(guān)于登錄窗口小功能的實現(xiàn)，沒有太大的必要用外觀層，可是以后要敲一個龐大的窗口時，我們須要將U層和B層解耦，那么外觀層的作用就彰顯出來了。關(guān)于BLL和外觀事實上沒有什么想說的。最想說的是數(shù)據(jù)類型的轉(zhuǎn)換，由于層與層之間傳遞參數(shù)和返回參數(shù)的過程須要用到相同類型的數(shù)據(jù)，可是將數(shù)據(jù)類型都設(shè)置為Datatable和string或者實體類型是不可能。希望大家在今后寫程序過程中注意就能夠了。

? ?本片文章代碼較多。希望大家拍磚斧正。。

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