root cause
java.lang.NoClassDefFoundError: org/apache/logging/log4j/spi/AbstractLoggerWrapper
网上资料比较少，最后查到是mybatis 3.2.7的bug，升级到3.3.0就好了
详见：
https://github.com/mybatis/mybatis-3/issues/234
emacarron modified the milestone: 3.2.8, 3.3.0 on 10 Oct 2014原文：http://www.cnblogs.com/binlin1987/p/7015663.html