Java单例模式

https://blog.csdn.net/chenchaofuck1/article/details/51702129

 

单例与序列化：

https://mp.weixin.qq.com/s?__biz=MzI3NzE0NjcwMg==&mid=2650120643&idx=1&sn=72ffc1018f5fe4451f885be56e972b30&chksm=f36bbce2c41c35f4d18a841b6fcc5688e7ab3d520be46bc72825b16c0d507a31e48f77dcf0fa&scene=21#wechat_redirect

 

枚举来实现单例

https://blog.csdn.net/tgvincent/article/details/91525095