单例模式

<span style="font-size:18px;">public class Singleton
{
	private volatile static Singleton singleton;
	private Singleton()
	{
		
	}
	public static Singleton getSingleton()
	{
		if(singleton==null){
			synchronized (Singleton.class)
			{
				if(singleton==null)
				{
					singleton=new Singleton();
				}
			}
		}
		return singleton;
	}
}</span>