实现原理解释：
http://blog.csdn.net/a596620989/article/details/6930479
http://stackoverflow.com/questions/85190/how-does-the-java-for-each-loop-work
查看字节码：
http://blog.csdn.net/hudashi/article/details/7062668
原文：http://www.cnblogs.com/Non-Tecnology/p/5309258.html