C#单例模式的三种写法

http://shansun123.iteye.com/blog/669942

第一种最简单，但没有考虑线程安全，在多线程时可能会出问题，不过俺从没看过出错的现象，表鄙视我……

public class Singleton

{

private static Singleton _instance = null;

private Singleton(){}

public static Singleton CreateInstance()

{

if(_instance == null)

{

_instance = new Singleton();

}

return _instance;

}

}

第二种考虑了线程安全，不过有点烦，但绝对是正规写法，经典的一叉

public class Singleton

{

private volatile static Singleton _instance = null;

private static readonly object lockHelper = new object();

private Singleton(){}

public static Singleton CreateInstance()

{

if(_instance == null)

{

lock(lockHelper)

{

if(_instance == null)

_instance = new Singleton();

}

}

return _instance;

}

}

第三种可能是C#这样的高级语言特有的，实在懒得出奇

public class Singleton

{

private Singleton(){}

public static readonly Singleton instance = new Singleton();

}

哦，shit！