JDK从6升级到7

近期，公司同时将JDK和Tomcat都升级到版本7，具体效益如下：
1，单Tomcat实例占用的堆栈内存由8G降低到3.6G。
2，接口平均响应时间较升级前优化20%左右。

参考资料
[1] Why Should I Switch to Java SE 7? - JavaOne 2012
http://www.oracle.com/javaone/lad-en/program/schedule/sessions/con7357-enok-1885660.pdf
[2] JDK 7 In Action（JDK 7实战） - Learn With Java Tutorials and
Developer Guides
https://blogs.oracle.com/thejavatutorials/entry/jdk_7_in_action_learn
Merge branch 'master' of https://github.com/EdwardLee03/Head_First_Design_Patterns