PermissionController權限管理類別

November 25, 2010

#Region “Var” Private _allPermission As T Private _permission As T #End Region

#Region “Public Property” Public Property AllPermission() As T Get Return _allPermission End Get Private Set(ByVal value As T) _allPermission = value End Set End Property

''' &lt;summary&gt;
''' Gets the permission.
''' &lt;/summary&gt;
''' &lt;value&gt;The permission.&lt;/value&gt;
Public Property Permission() As T
    Get
        Return _permission
    End Get
    Private Set(ByVal value As T)
        _permission = value
    End Set
End Property

#End Region

#Region “Constructor” ’’’ <summary> ’’’ Initializes a new instance of the <see cref=“PermissionController(Of T)” /> class. ’’’ </summary> ’’’ <param name=“permission”>The permission.</param> Public Sub New(ByVal permission As T) Dim permissionType As Type = GetType(T)

    If Not (permissionType.IsSubclassOf(GetType(System.Enum))) Then
        Throw New ArgumentException("permissionEnum must be a enum")
    End If

    If permissionType.GetCustomAttributes(GetType(FlagsAttribute), False).Length = 0 Then
        Throw New ArgumentException("permissionEnum must be a flag enum")
    End If

    LoadPermission(permission)
End Sub

#End Region

#Region “Private Method” ’’’ <summary> ’’’ Prepares all permission. ’’’ </summary> Private Sub PrepareAllPermission() Dim allPermissionValue As Integer = 0 For Each value As Integer In [Enum].GetValues(Permission.GetType) allPermissionValue = allPermissionValue Or value Next AllPermission = ConvertToEnum(allPermissionValue) End Sub

''' &lt;summary&gt;
''' Converts to value.
''' &lt;/summary&gt;
''' &lt;param name="permission"&gt;The permission.&lt;/param&gt;
''' &lt;returns&gt;&lt;/returns&gt;
Private Function ConvertToValue(ByVal permission As T) As Integer
    Return CInt(TryCast(permission, Object))
End Function

''' &lt;summary&gt;
''' Converts to enum.
''' &lt;/summary&gt;
''' &lt;param name="permissionValue"&gt;The permission value.&lt;/param&gt;
''' &lt;returns&gt;&lt;/returns&gt;
Private Function ConvertToEnum(ByVal permissionValue As Integer) As T
    Return DirectCast(TryCast(permissionValue, Object), T)
End Function

#End Region

#Region “Protected Method” ’’’ <summary> ’’’ Returns a <see cref=“System.String” /> that represents this instance. ’’’ </summary> ’’’ <returns> ’’’ A <see cref=“System.String” /> that represents this instance. ’’’ </returns> Public Overrides Function ToString() As String Return Me.Permission.ToString() End Function #End Region

#Region “Public Method” ’’’ <summary> ’’’ Loads the permission. ’’’ </summary> ’’’ <param name=“permission”>The permission.</param> Public Sub LoadPermission(ByVal permission As T) Me.Permission = permission PrepareAllPermission() End Sub

''' &lt;summary&gt;
''' Adds the permission.
''' &lt;/summary&gt;
''' &lt;param name="permission"&gt;The permission.&lt;/param&gt;
Public Sub AddPermission(ByVal permission As T)
    Me.Permission = ConvertToEnum(ConvertToValue(Me.Permission) Or ConvertToValue(permission))
End Sub

''' &lt;summary&gt;
''' Removes the permission.
''' &lt;/summary&gt;
''' &lt;param name="permission"&gt;The permission.&lt;/param&gt;
Public Sub RemovePermission(ByVal permission As T)
    Me.Permission = ConvertToEnum(ConvertToValue(Me.Permission) And (ConvertToValue(AllPermission) Xor ConvertToValue(permission)))
End Sub



''' &lt;summary&gt;
''' Determines whether the specified permission contains permission.
''' &lt;/summary&gt;
''' &lt;param name="permission"&gt;The permission.&lt;/param&gt;
''' &lt;returns&gt;
''' &lt;c&gt;true&lt;/c&gt; if the specified permission contains permission; otherwise, &lt;c&gt;false&lt;/c&gt;.
''' &lt;/returns&gt;
Public Function ContainsPermission(ByVal permission As T) As Boolean
    Return (ConvertToValue(Me.Permission) And ConvertToValue(permission)) = ConvertToValue(permission)
End Function

#End Region

End Class

&lt;Flags()&gt; _
Enum Permission
    None = 0
    Create = 1
    Read = 2
End Enum

Sub Main()
    Dim PermissionAgent As New PermissionController(Of Permission)(Permission.Create)
    Console.WriteLine("所有權限: {0}", PermissionAgent.AllPermission.ToString)
    Console.WriteLine("當前權限: {0}", PermissionAgent.Permission.ToString)
    Console.WriteLine("是否含權限{0}: {1}", Permission.Read, PermissionAgent.ContainsPermission(Permission.Read))
    Console.WriteLine("加入權限{0}...", Permission.Read)
    PermissionAgent.AddPermission(Permission.Read)
    Console.WriteLine("當前權限: {0}", PermissionAgent.Permission.ToString)
    Console.WriteLine("是否含權限{0}: {1}", Permission.Read, PermissionAgent.ContainsPermission(Permission.Read))
    Console.WriteLine("移除權限{0}...", Permission.Read)
    PermissionAgent.RemovePermission(Permission.Read)
    Console.WriteLine("當前權限: {0}", PermissionAgent.Permission.ToString)
    Console.WriteLine("移除權限{0}...", Permission.Create)
    PermissionAgent.RemovePermission(Permission.Create)
    Console.WriteLine("當前權限: {0}", PermissionAgent.Permission.ToString)
End Sub

End Module

VB.NET