02、概述1-面向对象分析和设计2015详解.ppt

* * * * * * 1-* Lecture Notes on Object-Oriented Technology (Programming Design) (Fall 2015) 第一讲 面向对象分析和设计 目标： 面向对象程序的构造过程 ★★ 分析和设计 面向对象的分析和设计 面向对象的构造过程 程序举例 * Problem： What is Analysis and Design? Analysis 强调对问题的调查，而不是确定解决方案。 “Do the right thing” Design强调的是系统的逻辑解决方案，即系统如何才能满足需求: 忽略详细的实现细节. 设计最终可以由硬件和软件实现。 “Do the thing right” 1.1 分析和设计 * Problem： What is Object-Oriented Analysis and Design? 精髓是用对象(things, concepts, or entities) 的观点考虑问题域和逻辑解决方案。 OOA: 重点在于发现和描述问题域中的对象和概念. OOD: 重点在于定义逻辑软件对象，以及对象如何协作实现需求. OO Programming: commitment to code. 1.2 面向对象分析和设计 * 面向对象程序设计是一个建模过程 建模 实体概念 类 抽象 具体 现 象 对 象 模拟 参照系统 程 序 问题空间（Problem Space） 解空间（Solution Space） * Example： An Example of Object-Oriented Analysis and Design A dice game: a player rolls two dice, if the total is seven he/she wins; otherwise he/she loses. 1.3 面向对象程序的构造过程 * 1 Defining Use Cases Understanding the requirements includes understanding the domain processes and the external environment (external actors who participate in processes). Use Case: Play a Game Actors: Player Description: Player requests to roll the dice. System presents results. If the dice face value totals seven, player wins; otherwise player loses. * 2 Defining a Domain Model A decomposition of the problem domain involves an identification of the concepts, attributes and associations in the domain that are considered important. * Example of a conceptual model Fig : The conceptual model is not a description of software components; it represents concepts in the real-world problem domain. Fig Partial domain model of the dice game. * 3 Defining Interaction Diagrams An essential step in OOD is the allocation of responsibilities to objects and illustrating how they interact via messages, expressed in sequence diagrams. Sequence diagrams show the flow of messages between instances and the invocation of methods. E.g. a simulation in