转自：http://www.cnblogs.com/BeyondAnyTime/archive/2012/07/10/2584272.html

转自：http://blog.youkuaiyun.com/fstar007/article/details/6941256

转自：http://blog.youkuaiyun.com/lilu_leo/article/details/7609496

单例类代码： package Singleton; public class LogMgr { //单例对象及获取单例对象的方法需要定义为static类型 private static LogMgr instance = new LogMgr(); public static LogMgr getInstance() { return

转自：http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html

转自：http://yongliang567.iteye.com/blog/904467

转自：https://my.oschina.net/pingpangkuangmo/blog/508963