设计模式（三）- Singleton模式续（多线程模式下的Singleton模式）

当为多线程的应用程序创建singleton设计模式时，需要确保它们都是线程安全的。

1Imports System.Threading
2
3Public Class Singleton_threadClass Singleton_thread
4
5 'private member
6 Private Shared m_Instance As Singleton_thread
7 Private Shared m_TimeOfBirth As String
8 Private Shared m_Mutex As New Mutex
9 Private Sub New()Sub New()
10 Console.WriteLine(String.Format("Creating Singleton at {0}", Now.ToLongTimeString))
11 m_TimeOfBirth = Now.ToLongTimeString
12 End Sub
13
14 'public member
15 Public Shared Function GetInstance()Function GetInstance() As Singleton_thread
16 m_Mutex.WaitOne()
17 If m_Instance Is Nothing Then
18 m_Instance = New Singleton_thread
19 End If
20 m_Mutex.ReleaseMutex()
21 Return m_Instance
22 End Function
23
24
25
26End Class