OO实例05.ppt

What is Object-Oriented? Object orientation is an approach to software development that organizes both the problem and its solution as a collection of discrete objects, It is a kind of representation that describe object’s data structure and behavior, It is a kind of modeling technology. Characteristics of OO Representation Identity—name, reference, handle Abstraction Classification Encapsulation Inheritance Polymorphism Persistence The OO Development Process Be consistency of terminology and the problem and the solution were described in same terms : classes, objects methods, attributes, and behaviors. Be consistency of perspective Static views Dynamic views Restrictions Tendency for Change when Using OO Paradigm(Jacobson et al. 1995) OO Requirements OO requirements analysis is usually done in the user’s language. The requirements definition can be independent of implement. OO requirements analysis discusses the concepts and scenarios likely in application domain. The concepts include information, service, and responsibilities. Domain knowledge enables both developers and users to understand the problems. OO Design Requirement specification, the first steps of design. To represent a system design First, to identify and represent classes and objects. Second, to identify the interactions and relationships among objects and classes. To provide the details in program design. Insert computational features in the models Insert some class library details Consider nonfunctional requirements Use Cases (用例） Describe particular functionality to exhibit how a user, external system, and other entity dialog with the system. Scenario 场景 Script 脚本 Use case diagrams（用例图） Actor（角色） A entity interacting with the system Or a role that an entity plays with respect of the system User Device Another system Cases（用例） A depiction of some aspect of functionality Extensions To extend a use case to illustrate a different or deeper perspective. Uses Actually a reuse of an already