设计模式——单例模式(代码基本参考自《大话设计模式》)

public class Singleton {
	private static Singleton instance = null;
	
	private static final Object lock = new Object();
	
	public Singleton(){
		
	}
	
	public static Singleton getInstance() {
	
		synchronized (lock) {
			if(instance == null) {
				instance = new Singleton();
			}
		}
		return instance;
	}
	
	public void  test() {
		System.out.println("获取对象....");
	}
	public static void main(String[] args) {
		Singleton singleton = Singleton.getInstance();
		singleton.test();
	}
}