Java NIO之多个Selector的实现
Java NIO类库Selector机制解析（上）
https://www.zhihu.com/question/19732473
http://blog.csdn.net/iter_zc/article/details/39291647
http://www.cnblogs.com/Anker/p/3254269.html
http://blog.csdn.net/historyasamirror/article/details/4270633
http://blog.csdn.net/historyasamirror/article/details/5778378