ORM(二)数据层的定义和实现。

在上一节中我们讲述了对OQL接口的定义和介绍。有了这部份的支持，我们今天来看看对数据操作的接口定义。

上面显示的数据提供器IDataProvider它直接继承了.Net框架的IDbCommand接口，我现在不知道为什么这样定义了，不知道这样定义有没有问题。


下面是对IDataProvider实现在的SQLServerDataProvider类。

Public Class SQLServerDataProvider

Implements Lily.Core.DataProvider.IDataProvider

#Region "成员变量"

Private md_Command As SqlClient.SqlCommand

Private md_Connection As SqlClient.SqlConnection

Private md_Tran As SqlClient.SqlTransaction

'是否自动关闭连接

Private md_blnAutoCloseConnection As Boolean = True

#End Region

#Region "类实例化"

''' -----------------------------------------------------------------------------

''' <summary>

''' 类实例化.

''' </summary>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Private Sub New()

End Sub

''' -----------------------------------------------------------------------------

''' <summary>

''' 类实例化

''' </summary>

''' <param name="connection">实例化所使用的连接对象.</param>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Sub New(ByVal connection As SqlClient.SqlConnection)

Me.InitConnection(connection)

End Sub

''' -----------------------------------------------------------------------------

''' <summary>

''' 类实例化.

''' </summary>

''' <param name="connectionString">连接字符串</param>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Sub New(ByVal connectionString As String)

Dim conn As New SqlClient.SqlConnection(connectionString)

Me.InitConnection(conn)

End Sub

'数据对象初始化

Private Sub InitConnection(ByVal connection As IDbConnection)

'连接对象

Me.md_Connection = connection

'创建命令对象

Me.md_Command = New SqlClient.SqlCommand

'命令对象的默认命令类型

Me.md_Command.CommandType = CommandType.Text

End Sub

#End Region

#Region "类公共属性"

#End Region

#Region "IDataProvider接口实现"

''' -----------------------------------------------------------------------------

''' <summary>

''' 开始一个事务.

''' </summary>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Sub BeginTransaction() Implements IDataProvider.BeginTransaction

Me.Open()

Me.Transaction = Me.Connection.BeginTransaction

End Sub

''' -----------------------------------------------------------------------------

''' <summary>

''' 关闭连接.

''' </summary>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Sub Close() Implements IDataProvider.Close

If Me.md_Connection Is Nothing Then

Return

Else

If Not Me.Command Is Nothing Then

Me.Command.Parameters.Clear()

End If

'连接没有打开

If Me.md_Connection.State <> ConnectionState.Open Then

Return

Else

'当前实例没有开启事务

If Me.Transaction Is Nothing Then

'自动关闭连接

If Me.AutoCloseConnection Then

Me.md_Connection.Close()

End If

End If

End If

End If

End Sub

''' -----------------------------------------------------------------------------

''' <summary>

''' 提交事务.

''' </summary>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Sub Commit() Implements IDataProvider.Commit

Me.Transaction.Commit()

Me.Close()

End Sub

''' -----------------------------------------------------------------------------

''' <summary>

''' 把查询结果填充到datatable对象

''' </summary>

''' <param name="datatable">要填充的datatable对象.</param>

''' <returns></returns>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Overloads Function Fill(ByVal datatable As System.Data.DataTable) As Integer Implements IDataProvider.Fill

Try

Me.Open()

DebugCommandText()

Dim da As SqlClient.SqlDataAdapter = New SqlClient.SqlDataAdapter(Me.Command)

Return da.Fill(datatable)

Catch ex As Exception

Throw New Lily.core.DataProvider.DataProviderException(ex.Message, ex)

Finally

Me.Close()

End Try

End Function

''' -----------------------------------------------------------------------------

''' <summary>

''' 把查询结果填充到datatset对象

''' </summary>

''' <param name="datatset">要填充的datatset对象.</param>

''' <returns></returns>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Overloads Function Fill(ByVal datatset As System.Data.DataSet) As Integer Implements IDataProvider.Fill

Try

Me.Open()

Dim da As SqlClient.SqlDataAdapter = New SqlClient.SqlDataAdapter(Me.Command)

DebugCommandText()

Return da.Fill(datatset)

Catch ex As Exception

Throw New Lily.core.DataProvider.DataProviderException(ex.Message, ex)

Finally

Me.Close()

End Try

End Function

''' -----------------------------------------------------------------------------

''' <summary>

''' 打开连接.

''' </summary>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Sub Open() Implements IDataProvider.Open

If Me.md_Connection.State <> ConnectionState.Open Then

Me.md_Connection.Open()

End If

End Sub

''' -----------------------------------------------------------------------------

''' <summary>

''' 回滚事务.

''' </summary>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Sub Rollback() Implements IDataProvider.Rollback

Me.Transaction.Rollback()

Me.Close()

End Sub

''' -----------------------------------------------------------------------------

''' <summary>

''' 试图取消命令的执行.

''' </summary>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Sub Cancel() Implements System.Data.IDbCommand.Cancel

Me.Command.Cancel()

End Sub

''' -----------------------------------------------------------------------------

''' <summary>

''' 获取或设置针对数据源运行的文本命令。

''' </summary>

''' <value></value>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Property CommandText() As String Implements System.Data.IDbCommand.CommandText

Get

Return Me.Command.CommandText

End Get

Set(ByVal Value As String)

Me.Command.CommandText = Value

End Set

End Property

''' -----------------------------------------------------------------------------

''' <summary>

''' 获取或设置在终止执行命令的尝试并生成错误之前的等待时间。

''' </summary>

''' <value></value>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Property CommandTimeout() As Integer Implements System.Data.IDbCommand.CommandTimeout

Get

Return Me.Command.CommandTimeout

End Get

Set(ByVal Value As Integer)

Me.Command.CommandTimeout = Value

End Set

End Property

''' -----------------------------------------------------------------------------

''' <summary>

''' 指示或指定如何解释CommandText 属性。

''' </summary>

''' <value></value>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Property CommandType() As System.Data.CommandType Implements System.Data.IDbCommand.CommandType

Get

Return Me.Command.CommandType

End Get

Set(ByVal Value As System.Data.CommandType)

Me.Command.CommandType = Value

End Set

End Property

''' -----------------------------------------------------------------------------

''' <summary>

''' 获取或设置IDbCommand 的此实例使用的

''' </summary>

''' <value></value>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Property Connection() As System.Data.IDbConnection Implements System.Data.IDbCommand.Connection

Get

Return Me.md_Connection

End Get

Set(ByVal Value As System.Data.IDbConnection)

md_Connection = Value

End Set

End Property

''' -----------------------------------------------------------------------------

''' <summary>

''' 创建一个参数对象.已设置了参数名称,参数的名称是根据GUID产生的避免了重复.

''' </summary>

''' <returns></returns>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Overloads Function CreateParameter() As System.Data.IDbDataParameter Implements System.Data.IDbCommand.CreateParameter

Return Me.Command.CreateParameter

End Function

''' -----------------------------------------------------------------------------

''' <summary>

''' 针对.NET Framework 数据提供程序的Connection 对象执行SQL 语句，并返回受影响的行数。

''' </summary>

''' <returns></returns>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Function ExecuteNonQuery() As Integer Implements System.Data.IDbCommand.ExecuteNonQuery

Try

Me.Open()

DebugCommandText()

Dim i As Integer = Me.Command.ExecuteNonQuery

Return i

Catch ex As Exception

Throw New Lily.core.DataProvider.DataProviderException(ex.Message, ex)

Finally

Me.Close()

End Try

End Function

''' -----------------------------------------------------------------------------

''' <summary>

''' 已重载。针对Connection 执行CommandText，并生成IDataReader。

''' </summary>

''' <returns></returns>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Overloads Function ExecuteReader() As System.Data.IDataReader Implements System.Data.IDbCommand.ExecuteReader

Try

Me.Open()

DebugCommandText()

Return Me.Command.ExecuteReader

Catch ex As Exception

Throw New Lily.core.DataProvider.DataProviderException(ex.Message, ex)

End Try

End Function

''' -----------------------------------------------------------------------------

''' <summary>

''' 已重载。针对Connection 执行CommandText，并生成IDataReader。

''' </summary>

''' <param name="behavior"></param>

''' <returns></returns>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Overloads Function ExecuteReader(ByVal behavior As System.Data.CommandBehavior) As System.Data.IDataReader Implements System.Data.IDbCommand.ExecuteReader

Try

Me.Open()

DebugCommandText()

Return Me.Command.ExecuteReader(behavior)

Catch ex As Exception

Throw New Lily.Core.DataProvider.DataProviderException(ex.Message, ex)

End Try

End Function

''' -----------------------------------------------------------------------------

''' <summary>

''' 执行查询，并返回查询所返回的结果集中第一行的第一列。忽略额外的列或行。

''' </summary>

''' <returns></returns>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Function ExecuteScalar() As Object Implements System.Data.IDbCommand.ExecuteScalar

Try

Me.Open()

DebugCommandText()

Dim obj As Object = Me.Command.ExecuteScalar

Return obj

Catch ex As Exception

Throw New Lily.core.DataProvider.DataProviderException(ex.Message, ex)

Finally

Me.Close()

End Try

End Function

''' -----------------------------------------------------------------------------

''' <summary>

''' 执行插入语句并返回自动增量的值.

''' </summary>

''' <returns></returns>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Function ExecuteIncrement() As Long Implements IDataProvider.ExecuteIncrement

'SCOPE_IDENTITY()

Try

Me.Open()

Me.CommandText = Me.CommandText & " " & " select SCOPE_IDENTITY()"

DebugCommandText()

Dim obj As Object = Me.Command.ExecuteScalar

Return obj

Catch ex As Exception

Throw New Lily.core.DataProvider.DataProviderException(ex.Message, ex)

Finally

Me.Close()

End Try

End Function

Public ReadOnly Property Parameters() As System.Data.IDataParameterCollection Implements System.Data.IDbCommand.Parameters

Get

Return Me.Command.Parameters

End Get

End Property

''' -----------------------------------------------------------------------------

''' <summary>

''' 在数据源上创建该命令的准备好的（或已编译的）版本。

''' </summary>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Sub Prepare() Implements System.Data.IDbCommand.Prepare

Me.Command.Prepare()

End Sub

''' -----------------------------------------------------------------------------

''' <summary>

''' 获取或设置在其中执行.NET Framework 数据提供程序的Command 对象的事务。

''' </summary>

''' <value></value>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Property Transaction() As System.Data.IDbTransaction Implements System.Data.IDbCommand.Transaction

Get

Return Me.Command.Transaction

End Get

Set(ByVal Value As System.Data.IDbTransaction)

Me.Command.Transaction = Value

End Set

End Property

''' -----------------------------------------------------------------------------

''' <summary>

''' 获取或设置命令结果在由DbDataAdapter 的Update 方法使用时如何应用于DataRow。

''' </summary>

''' <value></value>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Property UpdatedRowSource() As System.Data.UpdateRowSource Implements System.Data.IDbCommand.UpdatedRowSource

Get

Return Me.Command.UpdatedRowSource

End Get

Set(ByVal Value As System.Data.UpdateRowSource)

Me.Command.UpdatedRowSource = Value

End Set

End Property

Private IsDisposed As Boolean

''' -----------------------------------------------------------------------------

''' <summary>

''' 释放对象资源.

''' </summary>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Sub Dispose() Implements System.IDisposable.Dispose

If Not Me.IsDisposed Then

IsDisposed = True

If Not Me.md_Command Is Nothing Then Me.md_Command.Dispose()

If Not Me.md_Connection Is Nothing Then Me.md_Connection.Dispose()

If Not Me.md_Tran Is Nothing Then Me.md_Tran.Dispose()

Me.md_Command = Nothing

Me.md_Tran = Nothing

Me.md_Connection = Nothing

End If

End Sub

''' -----------------------------------------------------------------------------

''' <summary>

''' 返回或设置是否在执行完命令后自动关闭连接.

''' </summary>

''' <value></value>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public Property AutoCloseConnection() As Boolean Implements Core.DataProvider.IDataProvider.AutoCloseConnection

Get

Return Me.md_blnAutoCloseConnection

End Get

Set(ByVal Value As Boolean)

Me.md_blnAutoCloseConnection = Value

If Value Then

'关闭连接

Me.Close()

End If

End Set

End Property

''' -----------------------------------------------------------------------------

''' <summary>

''' 返回命令对象.

''' </summary>

''' <value></value>

''' <remarks>

''' </remarks>

''' <history>

''' [zqonline] 2006-10-20 Created

''' </history>

''' -----------------------------------------------------------------------------

Public ReadOnly Property Command() As System.Data.IDbCommand Implements Core.DataProvider.IDataProvider.Command

Get

Me.md_Command.Connection = Me.md_Connection

Return Me.md_Command

End Get

End Property

#End Region

#Region "私有方法"

Private Sub DebugCommandText()

If Not Me.Command Is Nothing Then

Lily.Core.Shared.DebugMessage.Invoke(Me.Command.CommandText)

End If

End Sub

#End Region

End Class

连接执行状态都是执行后就进行关闭，只有当使用事务或显示的指定不自动关闭连接时，需要手动关闭连接。其中方法DebugCommandText主要是用于显示或记录执行的语句。记录器需要外部提供。这里我是引用了组件Lily.Core.Dll.在后面的讲述，我们将进行介绍。此类的实现我就为系统提供了对数据库打交道的基石。

BS: 我在使用此类时，如果很频繁的对数据库进行打开和关闭操作。有时会出现连接池满的情况。由于我目前都是在WinForm下进行开发，所以只是针对WinForm进行设计和开发。

下一节准备开始讲实体。虽然这些代码是自己写的。不过没有进行过设计，现在写成文档居然比较陌生。目前为此我觉得在做信息系统的程序开发时最大的困难是类名，方法名，属性名的取名。