java8新特性

18.10.2前动手写了一遍。
不错的参考：
https://blog.csdn.net/liubenlong007/article/details/62039628
https://blog.csdn.net/u014470581/article/details/54944384
https://www.cnblogs.com/pkufork/p/java_8.html
https://www.cnblogs.com/justcooooode/p/7701260.html#_label3