本文介绍了类图，它用于展示系统中的类和类包，呈现系统各部分及其关系的静态画面，通常在逻辑视图中创建。还阐述了类的可见性设置，以及类之间的四种关系，包括关联、依赖、聚合、泛化，此外提到了实现关系，并给出示例类图。
6. Class Diagram <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
A class diagram is used to display some of the classes and packages of classes in your system. It gives a static picture of the pieces in the system, and of the relationships between them.
Please remember that we usually create a class diagram in the Logical View.
6.1 Setting Class Visibility
Public suggests that the class can be seen by all of the other classes in the system.
Protected, Private suggests that the class can be seen in nested classes, friends, or within the same class.
Package or Implementation suggests that the class can only be seen by other classes in the same package.
6.2 Class Relationships
There are four types of relationships you can set up between classes:
- Association
- Dependencies
- Aggregation
- Generalization
Associations
An association is a semantic connection between classes. An association allows one class to know about the public attributes and operations of other class.
Unidirectional & bidirectional associations exist in Rational Rose.
Dependencies
A dependency relationship shows that a class references another class. A change in the referenced class specification may impact the using class.
Aggregations
An aggregation is stronger form of association. An aggregation is a relationship between a whole and its parts.
A generalization is an inheritance relationship between two classes. It allows one class to inherit the public and protected attributes and operations of another class.
Realization
Realization indicates that one class implements behavior specified by another. It is permissible for one implementation class to realize another; this means that the realizing class must conform to the interface, but need not use inheritance.
There is a sample class diagram as follows.
扫一扫
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
