單例實現

Question

我寫了一段關於單例模式實現的代碼。不確定其正確性。請給點建議。謝謝。

public class Singleton 
{ 
    public Singleton Instance 
    { 
     get 
     { 
      if (_instance == null) 
      { 
       if (_mutexCreation.WaitOne(0)) 
       { 
        try 
        { 
         if (_instance == null) 
         { 
          _instance = new Singleton(); 
         } 
        } 
        finally 
        { 
         _mutexCreation.ReleaseMutex(); 
         _eventCreation.Set(); 
        } 

       } 
       else 
       { 
        _eventCreation.WaitOne(); 
       } 
      } 
      return _instance; 
     } 
    } 

    private Singleton() { } 

    private static Singleton _instance; 
    private static Mutex _mutexCreation = new Mutex(); 
    private static ManualResetEvent _eventCreation = new ManualResetEvent(false); 
} 

Answer 1

public class Singleton 
{ 
    private static object _syncRoot = new object(); 

    public Singleton Instance 
    { 
     get 
     { 
      if (_instance == null) 
      { 
       lock (_syncRoot) 
       { 
        if (_instance != null) 
         return _instance; 

        _instance = new Singleton(); 
       } 
      } 
      return _instance; 
     } 
    } 

    private Singleton() { } 
    private static Singleton _instance; 
} 

如果你不想使用延遲加載，乾脆直接在靜態構造函數創建一個新的實例。