UML类图中箭头的含义

Explanation of the UML arrows

Here's some explanations from the Visual Studio 2015 docs:

UML Class Diagrams: Reference: https://msdn.microsoft.com/library/dd409437%28VS.140%29.aspx

UML class diagram

5: Association: A relationship between the members of two classifiers.

5a: Aggregation: An association representing a shared ownership relationship. The Aggregation property of the owner role is set to Shared.

5b: Composition: An association representing a whole-part relationship. The Aggregation property of the owner role is set to Composite.

9: Generalization: The specific classifier inherits part of its definition from the general classifier. The general classifier is at the arrow end of the connector. Attributes, associations, and operations are inherited by the specific classifier. Use the Inheritance tool to create a generalization between two classifiers.

Package diagram

13: Import: A relationship between packages, indicating that one package includes all the definitions of another.

14: Dependency: The definition or implementation of the dependent classifier might change if the classifier at the arrowhead end is changed.

Realization relationship

15: Realization: The class implements the operations and attributes defined by the interface. Use the Inheritance tool to create a realization between a class and an interface.

16: Realization: An alternative presentation of the same relationship. The label on the lollipop symbol identifies the interface.

UML Class Diagrams: Guidelines: http://msdn.microsoft.com/library/dd409416%28VS.140%29.aspx

Properties of an Association

Aggregation: This appears as a diamond shape at one end of the connector. You can use it to indicate that instances at the aggregating role own or contain instances of the other.

Is Navigable: If true for only one role, an arrow appears in the navigable direction. You can use this to indicate navigability of links and database relations in the software.

 

Generalization: Generalization means that the specializing or derived type inherits attributes, operations, and associations of the general or base type. The general type appears at the arrowhead end of the relationship.

Realization: Realization means that a class implements the attributes and operations specified by the interface. The interface is at the arrow end of the connector.

Let me know if you have more questions. 

 

 

 

UML Designers have been removed; Layer Designer now supports live architectural analysis

We are removing the UML designers from Visual Studio “15” Enterprise. Removing a feature is always a hard decision, but we want to ensure that our resources are invested in features that deliver the most customer value.  Our reasons are twofold:

  1. On examining telemetry data, we found that the designers were being used by very few customers, and this was confirmed when we consulted with our sales and technical support teams.
  2. We were also faced with investing significant engineering resource to react to changes happening in the Visual Studio core for this release.

If you are a significant user of the UML designers, you can continue to use Visual Studio 2015 or earlier versions, whilst you decide on an alternative tool for your UML needs.

 

转载于:https://www.cnblogs.com/chucklu/p/10623671.html

<think>嗯,用户这次的问题聚焦在UML箭头含义和朝向上。从提问方式看,用户显然已经具备UML基础知识,现在需要更深入的符号语义解析。这问题通常是软件开发人员在设计模式学习或代码重构时遇到的痛点。注意到用户引用了四段资料:引用[1]介绍UML整体概念,引用[2][4]具体说明关系型,引用[3]强调的重要性。有趣的是用户特别截取了聚合组合的代码示例,可能暗示对关联强度概念存在困惑。结合上次对话历史(虽然无直接关联),用户应该正在做技术文档阅读或系统设计工作。需要重点区分的易混淆点有两个:一是空心箭头和实心箭头在泛化与实现中的不同用法;二是聚合组合的生存期差异。那个鸟和翅膀的代码示例非常典型——翅膀在鸟的构造函数中实例化(组合),如果是setWing()就是聚合了,这正好解释生存期强弱的区别。对依赖关系的说明要谨慎,因为虚线箭头常被误解。引用[2][4]都提到它是最弱的关系,但未说明具体表现形式。应该补充使用场景:比如A的方法参数包含B,或者A调用了B的静态方法。这点在代码层面最容易被忽视。箭头方向其实有内在逻辑:从子指向父(泛化)、实现指向接口(实现)、持有者指向被持有者(关联聚合组合)、依赖者指向被依赖者。这种“指向依赖方”的规律可以帮助记忆。不过聚合组合的菱形端方向需要单独强调。考虑到用户技术背景,准备在回答中添加实战技巧:比如在IDEA中查看时,如何识别插件生成的箭头型;还有处理循环依赖时箭头绘制的注意事项。用户可能正在反向工程某个项目,这些实操建议会比纯理论更有价值。</think> 根据引用内容,UML中的箭头及其朝向表示不同之间的关系,具体含义如下(使用$$...$$格式呈现核心关系定义): --- ### 一、箭头型与含义 #### 1. **泛化(Generalization)** - **符号**:**空心三角形实线 + 箭头朝向父** - **含义**:表示继承关系(is-a关系) - **示例**:`Dog → Animal`(Dog继承Animal) - **生存期**:子与父同生共死[^4] ``` $$ \text{子} \xrightarrow{\text{空心三角}} \text{父} $$ ``` #### 2. **实现(Realization)** - **符号**:**空心三角形虚线 + 箭头朝向接口** - **含义**:实现接口的功能 - **示例**:`Car → Movable`(Car实现Movable接口) ``` $$ \text{实现} \xrightarrow[\text{虚线}]{\text{空心三角}} \text{接口} $$ ``` #### 3. **关联(Association)** - **符号**:**普通实线箭头 + 箭头指向被拥有方** - **含义**:之间长期持有的引用关系 - **示例**:`Teacher → Student`(Teacher持有Student引用) - **生存期**:被关联对象可独立存在[^2][^4] #### 4. **聚合(Aggregation)** - **符号**:**空心菱形实线 + 箭头朝向部分** - **含义**:弱整体-部分关系(has-a关系),部分可独立存在 - **示例**:`Car → Wheel`(车轮可脱离汽车存在) ``` $$ \text{整体} \xleftarrow{\text{空心菱形}} \text{部分} $$ ``` #### 5. **组合(Composition)** - **符号**:**实心菱形实线 + 箭头朝向部分** - **含义**:强整体-部分关系(contains-a关系),部分随整体销毁 - **示例**:`Bird → Wing`(鸟死亡时翅膀同步销毁)[^4] ``` $$ \text{整体} \xleftarrow{\text{实心菱形}} \text{部分} $$ ``` #### 6. **依赖(Dependency)** - **符号**:**普通虚线箭头 + 箭头指向被依赖方** - **含义**:临时使用关系(如方法参数、局部变量) - **示例**:`Order → PaymentService`(订单短暂调用支付服务)[^2][^4] ``` $$ \text{使用方} \xrightarrow[\text{虚线}]{\text{}} \text{被依赖方} $$ ``` --- ### 二、箭头方向规则总结 | **关系型** | 箭头起点 | 箭头终点 | 方向逻辑 | |--------------|------------------|------------------|--------------------------| | 泛化/实现 | 子/实现 | 父/接口 | **指向更抽象的实体** | | 关联/聚合/组合| 主动持有者 | 被持有对象 | **指向依赖方** | | 依赖 | 调用者 | 被调用者 | **指向服务提供方** | > ⚠️ **关键区别**:聚合与组合的生存期控制(菱形端在**整体侧**) > - 聚合(空心菱形):删除`Car`时,`Wheel`仍可存在[^4] > - 组合(实心菱形):删除`Bird`时,`Wing`同步销毁[^4] ---
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