[类图和代码](https://gitee.com/OOAD2019Spring/Team18.C17007/raw/master/17180600727%E9%99%86%E5%BA%AD%E5%B3%B0/Observer/%E7%B1%BB%E5%9B%BE%E5%92%8C%E4%BB%A3%E7%A0%81%EF%BC%88%E5%AE%9E%E9%AA%8C%E6%8A%A5%E5%91%8A%EF%BC%89.zip)