好吧，官网上有写：
The current plan is that CXF 3.1 will no longer support Java 6 and will require Java 7 or newer. Users are strongly encouraged to start moving to Java 7.
http://fanshuyao.iteye.com/blog/2246409
Spring和CXF整合时报Unsupported major.minor version 51.0异常
原文：http://www.cnblogs.com/beijingstruggle/p/5453034.html