UML之关系：依赖 关联(聚合 组合) 泛化 实现

关联与依赖的区别(A [关联 or 依赖] B)：
关联是有A就有B，依赖有A不一定有B，是A在某个业务过程中(这也就是依赖常表现为方法参数的原因)会用到B。


Understanding UML Class Relationships:
https://vaughnvernon.co/?page_id=31

Association, Aggregation, Composition, Generalization, Realization, Dependency:
http://javapapers.com/oops/association-aggregation-composition-abstraction-generalization-realization-dependency/
Association vs. Dependency vs. Aggregation vs. Composition:
http://nirajrules.wordpress.com/2011/07/15/association-vs-dependency-vs-aggregation-vs-composition/
类关系阐微:
http://www.cnblogs.com/zjzkiss/archive/2007/05/06/736725.html