UML建模：https://www.cnblogs.com/joinclear/p/4552297.html
各类知识点：https://github.com/justjavac/free-programming-books-zh_CN#%E5%85%8D%E8%B4%B9%E7%9A%84%E7%BC%96%E7%A8%8B%E4%B8%AD%E6%96%87%E4%B9%A6%E7%B1%8D%E7%B4%A2%E5%BC%95