单件模式（Singleton Pattern）vb.net

单件模式（Singleton Pattern）这个模式的技术简单明了：
（1）隐藏默认类的构造函数

（2）添加一个共享的成员，以引用单独的、实例化的对象

（3）创建一个公有函数来创建或返回被引用的对象

 

Public Class Mysingleton
    Private Shared m_Instance As Mysingleton
    Private Shared m_TimeOfBirth As String
    Private Sub New()
        Console.WriteLine("Creating Singleton at {0}", Now.ToLongTimeString)
        m_TimeOfBirth = Now.ToLongTimeString
    End Sub

    Public Shared Function GetInstance() As Mysingleton
        If m_Instance Is Nothing Then
            m_Instance = New Mysingleton()
        End If
        Return m_Instance
    End Function

    Public ReadOnly Property TimeOfbirth() As String
        Get
            Return m_TimeOfBirth
        End Get
    End Property
End Class

 

 

  Sub Main()
        Dim obTest1 As Mysingleton
        Dim obTest2 As Mysingleton
        Dim i As Integer
        obTest1 = Mysingleton.GetInstance()
        Console.WriteLine("GetInstance() called at {0} ; obtest1.TimeofBirth()={1}", Now.ToLongTimeString, obTest1.TimeOfbirth)
        For i = 1 To 50000000

        Next

        obTest2 = Mysingleton.GetInstance
        Console.WriteLine("GetInstance() called at {0} ; obtest2.TimeofBirth()={1}", Now.ToLongTimeString, obTest2.TimeOfbirth)
        MessageBox.Show("click ok to end")

end sub

 

多线程

Public Class Mysingleton
    Private Shared m_Instance As Mysingleton
    Private Shared m_TimeOfBirth As String
    '多线程安全
    Private Shared m_Mutex As New System.Threading.Mutex

    Private Sub New()
        Console.WriteLine("Creating Singleton at {0}", Now.ToLongTimeString)
        m_TimeOfBirth = Now.ToLongTimeString

    End Sub

    Public Shared Function GetInstance() As Mysingleton
        m_Mutex.WaitOne()
        If m_Instance Is Nothing Then
            m_Instance = New Mysingleton()
        End If
        m_Mutex.ReleaseMutex()
        Return m_Instance
    End Function

    Public ReadOnly Property TimeOfbirth() As String
        Get
            Return m_TimeOfBirth
        End Get
    End Property
End Class