Java Thread join() 的用法
http://auguslee.iteye.com/blog/1292203
http://blog.csdn.net/longronglin/article/details/2118670
http://bianrongxin.iteye.com/blog/1356220 一个错误写法
一种控制方法(类似于自定义信号量) http://www.blogjava.net/santicom/archive/2011/09/02/357783.html