下面给出三种实现方法,分别给出优缺点。
方法一:
public sealed class Singleton
{
private static readonly Singleton instance = new Singleton();
private Singleton(){}
public static Singleton Instance
{
get
{
return instance;
}
}
}
优点:简单明了
缺点:耗费资源
方法二:
public sealed class ClassicSingleton
{
private static ClassicSingleton instance;
private static object syncRoot = new Object();
private ClassicSingleton() { }
public static ClassicSingleton Instance
{
get
{
if (instance == null)
{
lock (syncRoot)
{
if (instance == null)
{
//...custom code
instance = new ClassicSingleton();
}
}
}
return instance;
}
}
}
优点:节省资源
缺点:代码冗长
方法三:
优点:既节省资源,又简单明了
缺点:线程不安全???
方法四:
public class Singleton
{
private static Singleton instance;
// Added a static mutex for synchronising use of instance.
private static System.Threading.Mutex mutex;
private Singleton() { }
static Singleton()
{
instance = new Singleton();
mutex = new System.Threading.Mutex();
}
public static Singleton Acquire()
{
mutex.WaitOne();
return instance;
}
// Each call to Acquire() requires a call to Release()
public static void Release()
{
mutex.ReleaseMutex();
}
}
优点:既节省资源,又简单明了,线程也同步了(一箭三雕)
缺点:轻微冗长
说明:前面三种方法都没有线程同步(真的需要同步吗?)
public sealed class Singleton
{
static Singleton(){Instance = new Singleton();}
private Singleton(){}
public static Singleton Instance{get; private set;}
}
http://www.cnblogs.com/k-sharp/archive/2010/05/26/1744121.html