机房重构---七层登录

前言：

从C#版三层登录开始，到VB.NET版三层登录，再到VB.NET版七层登录，一步步走向机房重构的正规化，其中也经历了很多的波折。刚开始不知道从哪里下手，不断的查询各种资料，慢慢了解，终于有了进展，还是蛮开心的。我的建议是如果实在不知道如何下手，没有思路，别停滞不前，不防先从简单的代码敲起，不断敲，不断查询学习，敲着敲着就会慢慢培养出感觉来。

七层构成：

七层和三层相比，多了一个外观层（Facade）、一个接口层（IDAL）、还多了一个工厂层（Factory）。关于sqlHelper可以单独放到一个包中（如下图），也可以和DAL层放到一起。

七层登录：

U层：

接受用户传来的数据，传给外观层，再由外观层传给B层进行相应的判断。

'**********************************************'文件名：frmLogin'作者：袁甜梦'小组：袁甜梦'说明:'创建日期：2016/2/29 19:40:40'版本号：V1.0.0.0'**********************************************Imports EntityImports FacadePublic Class frmLogin    Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click        '进行输入框的判断        If txtUserName.Text = "" Then            MsgBox("请输入用户名!", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)            txtUserName.Focus()            Exit Sub        End If        If IsNumeric(txtUserName.Text) = False Then            MsgBox("用户名请输入数字！", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)            txtUserName.Text = ""            Exit Sub        End If        If txtPassword.Text = "" Then            MsgBox("请输入密码！", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)            txtPassword.Focus()            Exit Sub        End If        Try            '实例化所需的各层的类            Dim Facade As New Facade.LoginFacade            Dim UserInfo As New Entity.LoginUserInfo            UserInfo.UserName = txtUserName.Text.Trim            UserInfo.Password = txtPassword.Text            Dim strResult As Boolean            '将U层的信息传入外观层，然后再有外观层传入B层进行判断            strResult = Facade.CheckUser(UserInfo)            If strResult = False Then   '判断用户是否存在                MsgBox("该用户不存在，请重新输入！", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)                txtUserName.Text = ""                txtPassword.Text = ""                txtUserName.Select()                txtUserName.Focus()            End If            Dim table As DataTable            table = Facade.CheckPwd(UserInfo)            If Trim(txtPassword.Text) = Trim(table.Rows(0).Item(2)) Then                MsgBox("登录成功！")                Me.Hide()                txtUserName.Text = ""                txtPassword.Text = ""            End If        Catch ex As Exception            MsgBox("用户不存在或密码不正确！")            txtPassword.Text = ""            txtUserName.Text = ""            txtUserName.Select()            txtUserName.Focus()        End Try    End Sub    Private Sub btnCancel_Click(sender As Object, e As EventArgs) Handles btnCancel.Click        Me.Close()    End SubEnd Class

Facade层：

解耦U层和B层。

'**********************************************'文件名：LoginFacade'作者：袁甜梦'小组：袁甜梦'说明:'创建日期：2016/2/29 19:11:40'版本号：V1.0.0.0'**********************************************Imports BLLImports EntityPublic Class LoginFacade    '判断用户是否存在    Public Function CheckUser(ByVal UserInfo As Entity.LoginUserInfo) As Boolean        Dim IsUserExists As New BLL.LoginBLL        Dim flag As Boolean        flag = IsUserExists.Checkuser(UserInfo)        If flag = True Then            Return True        Else            Return False        End If    End Function    '判断密码是否正确    Public Function CheckPwd(ByVal UserInfo As Entity.LoginUserInfo) As DataTable        Dim IsPwdExists As New BLL.LoginBLL        Dim table As DataTable        table = IsPwdExists.Checkpwd(UserInfo)        Return table    End FunctionEnd Class

BLL层：

'**********************************************'文件名：LoginBLL'作者：袁甜梦'小组：袁甜梦'说明:'创建日期：2016/2/29 17:30:53'版本号：V1.0.0.0'**********************************************Imports IDALImports EntityImports FactoryPublic Class LoginBLL    '检查用户是否存在    Public Function Checkuser(ByVal UserInfo As Entity.LoginUserInfo) As Boolean        Dim Factory As New Factory.LoginFactory        Dim IUser As IDAL.LoginIUserInfo        '调用创建用户的工厂方法        IUser = Factory.CreateIUser() '调用工厂的CreateIUser方法创建IUser接口实例        Dim table As New DataTable        Dim flag As Boolean        table = IUser.selectUser(UserInfo)        If table.Rows.Count = 0 Then            flag = False        Else            flag = True        End If        Return flag    End Function    '检查用户密码是否正确    Public Function Checkpwd(ByVal UserInfo As Entity.LoginUserInfo) As DataTable        Dim Factory As New Factory.LoginFactory        Dim IUser As IDAL.LoginIUserInfo        Dim table As DataTable        IUser = Factory.CreateIUser        table = IUser.selectUser(UserInfo)        Return table    End FunctionEnd Class

Factory层：

'**********************************************'文件名：LoginFactory'作者：袁甜梦'小组：袁甜梦'说明:'创建日期：2016/2/29 17:36:26'版本号：V1.0.0.0'**********************************************Imports System.Reflection '反射Imports System.Configuration '配置文件Imports System.DataImports IDALPublic Class LoginFactory    Private Shared ReadOnly AssemblyName As String = "DAL" '数据程序集名称，命名空间DAL    Dim strDB As String = System.Configuration.ConfigurationSettings.AppSettings("DB")    Public Function CreateIUser() As LoginIUserInfo        Dim classname As String = "DAL" + "." + strDB + "LoginDAL" '要实例化的D层的名称        'Dim classname As String = "DAL" + "." + "LoginDAL"        Dim IUser As LoginIUserInfo        'CType函数将返回表达式显示的转换为指定的数据类型、对象、结构、类或接口后的结果        IUser = CType(Assembly.Load(AssemblyName).CreateInstance(classname), LoginIUserInfo) '返回LoginIUserInfo        Return IUser    End FunctionEnd Class

IDAL层：

Imports EntityPublic Interface LoginIUserInfo    '判断用户是否存在    Function selectUser(ByVal UserInfo As Entity.LoginUserInfo) As DataTableEnd Interface

DAL层：

'**********************************************'文件名：LoginDAL'作者：袁甜梦'小组：袁甜梦'说明:'创建日期：2016/3/1 15:24:24'版本号：V1.0.0.0'**********************************************Imports EntityImports IDALImports SqlHelperImports System.Data.SqlClient    Public Class LoginDAL : Implements IDAL.LoginIUserInfo        '实现接口中的方法        Private sqlHelper As New SqlHelper.sqlhelper        '判断用户是否存在        Public Function selectUser(UserInfo As LoginUserInfo) As DataTable Implements LoginIUserInfo.selectUser            Dim sql As String '中间变量，用于存储从数据库中查到的信息        Dim table As DataTable        '声明并实例化参数数组        Dim sqlParams As SqlParameter() = {New SqlParameter("@UserName", UserInfo.UserName),                                              New SqlParameter("@Password", UserInfo.Password)}        sql = "select * from Users where UserName=@UserName and Password=@Password"        '调用sqlHelper类中的ExecSelect方法来执行查询并获取返回值            table = sqlHelper.ExecSelect(sql, CommandType.Text, sqlParams)            Return table        End Function    End Class

sqlHelper层：

'**********************************************'文件名：sqlhelper'作者：袁甜梦'小组：袁甜梦'说明:'创建日期：2016/2/29 16:07:28'版本号：V1.0.0.0'**********************************************Imports System.DataImports System.Data.SqlClientImports System.ConfigurationPublic Class sqlhelper    '数据库连接    Dim strConnction As String = "Server=YUAN; Database=StudentInfo;User ID=sa;Password=930201"    Dim conn As New SqlConnection(strConnction)    Dim cmd As New SqlCommand    Public Function ExecSelect(ByVal cmdText As String, ByVal cmdType As CommandType, ByVal paras As SqlParameter()) As DataTable        Dim sqlAdapter As SqlDataAdapter '定义数据适配器        Dim dt As New DataTable        Dim ds As New DataSet        '给cmd赋值        cmd.CommandText = cmdText 'cmdText为所要执行的sql语句        cmd.CommandType = cmdType '命令执行的类型        cmd.Connection = conn        cmd.Parameters.AddRange(paras) '参数添加        sqlAdapter = New SqlDataAdapter(cmd) '实例化Adapter        Try            sqlAdapter.Fill(ds) '用adapter将dataset填充            dt = ds.Tables(0) 'datatable为dataSet的第一个表            cmd.Parameters.Clear() '清除参数        Catch ex As Exception            MsgBox("数据库操作")        Finally            Call CloseCmd(cmd) '销毁cmd命令        End Try        Return dt    End Function    Public Sub CloseCmd(ByVal cmd As SqlCommand)        If Not IsNothing(cmd) Then 'cmd命令存在            cmd.Dispose() '销毁            cmd = Nothing        End If    End SubEnd Class

Entity层：

'**********************************************'文件名：LoginEntity'作者：袁甜梦'小组：袁甜梦'说明:'创建日期：2016/2/29 15:41:43'版本号：V1.0.0.0'**********************************************Public Class LoginUserInfo    '设置用户名属性    Private _username As String    Public Property UserName As String        Get            Return _username        End Get        Set(value As String)            _username = value        End Set    End Property    Private _password As String    '设置密码的属性    Public Property Password As String        Get            Return _password        End Get        Set(value As String)            _password = value        End Set    End PropertyEnd Class

配置文件：

<?xml version="1.0" encoding="utf-8" ?><configuration>  <startup>    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />  </startup>  <appSettings>    <add key="connstring" value="Server=YUAN;Database=StudentInfo;User ID=sa;Password=930201"/>  </appSettings ></configuration>

运行结果：

注意：

在运行之前需要更改DAL的编译路径，否则会出现错误。

错误提示：

路径更改方法：