uml课件Lect8-Grad-OO-Chapter5-notation-4.pptVIP

Lecture 8. UML Notation 4 内容提要： 1. State Machine Diagrams (状态机图) (Grady Booch Book 5.11) 2. Object Diagrams (对象图) (Grady Booch Book 5.13) 3. Communication Diagrams (通信图) (Grady Booch Book 5.14) 5.11 State Machine Diagram 状态机图概念：状态机图表示某对象在不同状态下的行为。状态的转换由事件或者相关行为引起 A state machine diagram expresses behavior as a progression through a series of states, triggered by events, and the related actions that may occur. 状态机图既可以用来描述单个对象的行为；也可以描述系统的大元素的行为状态 State machine diagrams are typically used to describe the behavior of individual objects, also can be used to describe the behavior of larger elements of any system. The two essential elements of a state machine diagram are states and state transitions. 并不是每个类都有事件驱动的行为。 状态机图的作用：表示系统的事件行为 We may also provide state machine diagrams that show the event-ordered behavior of the system as a whole. During analysis, we may use state machine diagrams to indicate the dynamic behavior of the system.分析阶段，使用状态图表示系统的动态行为 During design, we use state machine diagrams to capture the dynamic behavior of individual classes or of collaborations of classes. 设计阶段，使用状态图表示类的动态行为 Essentials: Initial, Final, and Simple States 在任何给定的时间点，对象的状态包括其所有的性质 At any given point in time, the state of an object encompasses all of its properties. 对象的性质：对象的属性和该对象与其它对象之间的关系的总和 Properties: the totality of the object’s attributes and relationships with other objects. 单个对象的状态也可以应用到其类中 An individual object’s state can be applied to the object’s class because all instances of the same class live in the same state space, which encompasses an indefinite yet finite number of possible states. 在给定的状态中，某个对象可以做如下的事情 When an object is in a given state, it can do the following: Execute an activity 进行一项活动 Wait for an event 等待某个事件 Fulfill a condition 满足一个条件 Do some or all of the above 做所有以上的事情 Initial state (必须有) In every state machine diagram, there must be exactly one default initial state, designated by an unlabeled transition to the state from a special icon