我自己写机房的时候，看很多高人的博客，各种的借鉴，当初务必的纠结，现在整个机房敲完了，写这篇博客给大家一个整体上的、简单理解的七层，期望大家看完这篇文章之后，不会这个纠结了。

首先大家得看了我的上一篇博客：

http://www.jb51.cc/article/p-hlmbvbyh-bme.html

我再说就会好说一点，大家只要理解了那张包图之后就可以了。

首先我还是拿最老套、最简单、最先开始的例子Login开始：

1、我们要知道Login需要那几步：查询user表，判断用户是否存在；在worklog中添加用户日志。

2、需要的数据库设计：

这里我就不另外建表，这样大家看的更熟悉，是吧？

3、建立Entity

实体是根据表来建立的，也就是说，表中有几个字段，Entity的LoginEntity和WorklogEntity类就有几个property。

本着面面俱到的原则，我就晒晒代码，大家别嫌我麻烦：

'**************************
'文 件 名：UserLogin
'命名空间：Entity
'内    容：
'功    能：
'文件关系：
'作    者：邱慕夏
'小    组：邱慕夏
'生成日期：2014-06-07 17:27:28
'版 本 号：V1.0.0.0
'修改日志：
'版权说明：
'***************************
Public Class LoginEntity
#Region "定义变量"
    Private _userID As String
    Private _level As String
    Private _Head As String
    Private _password As String
    Private _oldpassword As String
    Private _userName As String
    Private _computer As String

#End Region
    Public Shared UserHead As String              '设置全局变量
    Public Shared UserLevel As String
    Public Property UserID() As String            '将T_User_DAL表中的每一个实体都传上去，实体是根据表来建的，不是功能
        Get
            Return _userID
        End Get
        Set(ByVal value As String)
            _userID = value
        End Set
    End Property
    Public Property Level() As String
        Get
            Return _level
        End Get
        Set(ByVal value As String)
            _level = value
        End Set
    End Property
    Public Property Head() As String
        Get
            Return _Head
        End Get
        Set(ByVal value As String)
            _Head = value
        End Set
    End Property
    Public Property Password() As String
        Get
            Return _password
        End Get
        Set(ByVal value As String)
            _password = value
        End Set
    End Property
    Public Property OldPassword() As String
        Get
            Return _oldpassword
        End Get
        Set(ByVal value As String)
            _oldpassword = value
        End Set
    End Property
    Public Property UserName() As String
        Get
            Return _userName
        End Get
        Set(ByVal value As String)
            _userName = value
        End Set
    End Property
    Public Property computer() As String
        Get
            Return _computer
        End Get
        Set(ByVal value As String)
            _computer = value
        End Set
    End Property

End Class

上面是LoginEntity的，下面是Worklog的：

'**************************
'文 件 名：WorkLogEntity
'命名空间：Entity
'内    容：
'功    能：
'文件关系：
'作    者：邱慕夏
'小    组：邱慕夏
'生成日期：2014/6/15 11:07:47
'版 本 号：V1.0.0.0
'修改日志：
'版权说明：
'***************************
Public Class WorkLogEntity
    Private _userid As String
    Private _level As String
    Private _loginDateTime As String
    Private _logoutDateTime As String
    Private _computer As String
    Private _status As String
    Public Shared Property Login_DateTime As String


    Public Property UserID() As String
        Get
            Return _userid
        End Get
        Set(ByVal value As String)
            _userid = value
        End Set
    End Property
    Public Property Level() As String
        Get
            Return _level
        End Get
        Set(ByVal value As String)
            _level = value
        End Set
    End Property
    Public Property LoginDateTime() As String
        Get
            Return _loginDateTime
        End Get
        Set(ByVal value As String)
            _loginDateTime = value
        End Set
    End Property
    Public Property logoutDateTime() As String
        Get
            Return _logoutDateTime
        End Get
        Set(ByVal value As String)
            _logoutDateTime = value
        End Set
    End Property
    Public Property Computer() As String
        Get
            Return _computer
        End Get
        Set(ByVal value As String)
            _computer = value
        End Set
    End Property
    Public Property Status() As String
        Get
            Return _status
        End Get
        Set(ByVal value As String)
            _status = value
        End Set
    End Property
End Class

以上都是准备工作，由于篇幅，看下一篇。