Spring事务传播行为:https://www.cnblogs.com/softidea/p/5962612.html
数据库事务隔离级别:
https://www.cnblogs.com/huanongying/p/7021555.html
https://www.cnblogs.com/lenther2002/p/4487123.html
http://blog.sina.com.cn/s/blog_5dbd4f7e01018n8s.html