java并发资料整理

乐观锁和悲观锁，CAS操作：
http://286.iteye.com/blog/2295165
volatile 关键字：
http://www.techug.com/post/java-volatile-keyword.html
https://blog.csdn.net/championhengyi/article/details/77151002
https://www.jianshu.com/p/157279e6efdb
sync关键字：
http://www.cnblogs.com/butterfly100/p/8786856.html