Chapter 18 UML-系统设计

Illustrated with a dashed arrow
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设计类图—类关系

导航 Navigability

By default the associations are bidirectional. Sometimes you want to limit the message sending to only one direction. Classes with associations can navigate (send messages) to each other. Illustrated with an arrow pointing in the direction a message can be sent.

接口类

Which provides the means by which an actor can interface with the system.

Examples include a window, dialogue box, or screen. For nonhuman actors, an application program interface (API) is the interface object.
7: Return all product information
1..*
6: Return detailed product information
类的责任通过类的行为（一个 或多个方法）以及同其他类之 间的协作得以体现。 每个类收到请求消息时，都有 责任响应消息并实现请求。
Product
Member Ordered Product 0..*

详细设计过程-use case by use case

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确定并分类用例设计类
Place new order 各种类
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RMO Domain Model Class Diagram
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First-cut RMO Design Class Diagram
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确定类属性 确定类行为和责任 Place new order 用例中包含的行为

设计阶段的主要工作内容 workstation
Desktop PC

Application Server
Database Server

Entire System
Foreign System
2
面向对象的系统设计

学习目标

区分实体类、接口类、控制类、持续类和系统类 理解依赖关系和导航关系 定义可见性及其三个层次
retrieve from and send data to database

控制类

Which contains application logic that isn’t the responsibility of an entity object.

Examples of such logic are business rules and calculations that involve multiple objects Control objects coordinate messages between interface objects and entity objects and the sequences in which the messages occur.

Use well-established design principles such as coupling, cohesion, separation of responsibilities
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“下订单”用例的 第6步顺序图
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“通过关键字查询产品目录”的用例顺序图
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Place new order 用例的部分类图
第18章 使用UML进行 面向对象设计和建模
信息管理系 杨铭 yangming@
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Review

Moving From Business Modeling Requirements to Design

Completes the transition from analysis to design Architecture design Network design Application design modules User interfaces Design Forms and reports Control of inputs and outputs Database Design System interfaces Design
1: Message to request to display a customer抯order information
Customer Order
8: Display customer order
3: Return customer information 4: Message to request all products that an order contains


理解对象责任 描述面向对象包括的设计活动 使用顺序图建模交互类
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18.1 设计面向对象系统
1. 设计类图—类

基本类

实体类

Which contains business-related information that is typically persistent and stored in a database.
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精炼分析用例

“设计”用例的转换

Transforming the “Analysis” Use Cases to “Design” Use Cases Updating the Use Case Model Diagram and Other Documentation to Reflect any New Use Cases
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Place new order 用例中包含的Auto行为
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确定类之间的协作

CRC卡—类责任协作卡
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系统设计

确定类行为---交互图之顺序图 Realizing Use Case and Defining Methods Determine what objects collaborate by sending messages to each other to carry out use case Sequence diagrams and collaboration diagrams represent results of design decision
？
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18.2 面向对象设计过程

对用例模型加以精炼以反映实现环境
-- 将“分析”用例转化成“设计”用例 -- 修改用例模型图和其他文档以反映新用例

建模支持用例情景的类交互、行为和状态
-- 确定并分类用例设计类 -- 确定类属性 -- 确定类行为和责任 -- 建模对象状态

修改对象模型以反映实现环境
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3. 设计类图—属性与方法的可见性

可见性

the level of access an external object has to an attribute or method. 属性与方法如何被其他对象访问的约定。



Public attributes/methods can be accessed/invoked by any other method in any other object or class. Denoted by the symbol + Protected attributes/methods can be accessed/invoked by any method in the same class or in subclasses of that class. Denoted by the symbol # Private attributes/methods can be accessed/invoked by any method in the same class. Denoted by the symbol –
is for 1
5: Message to request detailed product information
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Diagrams in analysis： Use case diagrams use case descriptions activity diagrams domain class diagrams system sequence diagrams
Protected
friendly
只有在与A同包的类中才能够通过A的对象来 访问这个friendly域 可以
Public
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4. 设计类图—类的责任划分
2: Message to request customer information
Customer 1 submits 0..* 1 Order

其他

持续类、系统类
4
图示
Design Class Notation
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2. 设计类图—类关系

依赖关系 dependency relationship

is used to model the association between two classes:

To indicate that when a change occurs in one class, it may affect the other class. To indicate the association between a persistent class and a transient class. Interface classes typically are transient