listen_snow的心情坊

Asystemis a collection of subsystems organized to accomplish a purpose and described by a set of models, possibly from different viewpoints. Asubsystems is a grouping of elements, some

 When you model classes in the UML, remember that every class should map to some tangible or conceptual abstraction in the domain of the end user or the implementer. A well-structured class1.P

 Modeling the Vocabulary of a System为系统的词汇表建模 You’ll use classes most commonly to model abstractions that are drawn from the problem you are trying to solve or from the technology you are 

A relationship is a connection among things. In object-oriented modeling, the three most important relationships are dependencies, generalizations, and associations. Graphically, a relatio

If you are building a house, things like walls, doors, windows, cabinets, and lights will form part of your vocabulary. None of these things stands alone, however. Walls connect to other wal

Relationships关联 When you build abstractions, you’ll discover that very few of your classes stand alone. Instead, most of them collaborate with others in a number of ways. Therefore, when you

 Modeling Primitive Types构建原始类型模型 At the other extreme, the things you model may be drawn directly from the programming language you are using to implement a solution. Typically, these abs

Modeling Single Inheritance建模简单的继承 In modeling the vocabulary of your system, you will often run across classes that are structurally or behaviorally similar to others. You could model

Modeling Structural Relationships建模结构关系 When you model with dependencies or generalization relationships, you may be modeling classes that represent different levels of importance or d

Common DivisionsIn modeling object-oriented systems, the world often gets divided in several ways.First, there is the division of class and object. A class is an abstraction; an object is one

Extensibility Mechanisms The UML provides a standard language for writing software blueprints, but it is not possible for one closed language to ever be sufficient to express all possible nuan

ArchitectureVisualizing, specifying, constructing, and documenting a software-intensive system demands that the system be viewed from a number of perspectives. Different stakeholders ---- end

This class diagram captures the basics of the“Hello, World!” application, but it leaves out a number of things. As the preceding code specifies, two other classes----Applet andGraphics----ar

This figure makes it clear thatHelloWorld is just a leaf in a larger hierarchy of classes.HelloWorld is a child ofApplet ;Appletis a child of Panel ;Panel is a child ofContainer

Artifacts工件“Hello, World!” is implemented as an applet, so it never stands alone but instead is typically a part of some Web page. The applet starts when its enclosing page is opened, trigge

Terms and Concepts术语和概念 A classis a description of a set of objects that share the same attributes, operations, relationships, and semantics. Graphically, a class is rendered as a rectan

Organizing Attributes and Operations组织属性和操作 When drawing a class, you don’t have to show every attribute and every operation at once. In fact, in most cases, you can’t (there are too man

Modeling the Distribution of Responsibilities in a System为系统的职责分配建模 Once you start modeling more than just a handful of classes, you will want to be sure that your abstractions provide a b

 Modeling Simple Dependencies建模简单的依赖 A common kind of dependency relationship is the connection between a class that uses another class as a parameter to an operation.To model this u

Modeling Different Views of a System建模系统的不同视图When you model a system from different views, you are in effect constructing your system simultaneously from multiple dimensions. By choosing

Structural DiagramsThe UML’s structural diagrams exist to visualize, specify, construct, and document the static aspects of a system. You can think of the static aspects of a system as r

 When you work with an architect to design a house, you start with three things: a list of wants (such as“I want a house with three bedrooms” and “I want to pay no more thanx”), a

DIAGRAMS图群 When you model something, you create a simplification of reality so that you can better understand the system you are developing. Using the UML, you build your models from

Constraints约束 Everything in the UML has its own semantics. Generalization (usually, if you know what’s good for you) implies the LisKov substitution principle, and multiple associati

When you adorn a model with notes,lUse notes only for those requirements, observations, reviews, and explanations that you can’t express simply or meaningfully using existing features of

Modeling New Semantics新语义建模 When you create a model using UML, you work within the rules the UML lays down. That’s a good thing, because it means that you can communicate your intent

Modeling Comments注释建模 The most common purpose for which you’ll use notes is to write down free-form observations, reviews, or explanations. By putting these comments directly in your

Modeling New Properties新特性建模 The basic properties of the UML’s building blocks-----attributes and operations for classes, the contents of packages, and so on----are generic enough to

 Stereotypes模式化 The UML provides a language for structural things, behavioral things, grouping things, and notational things. These four basic kinds of things address the overwhelming

Notes备注 A note that renders a comment has no semantic impact, meaning that its contents do not alter the meaning of the model to which it is attached. This is why notes are used to spe

 Terms and Concepts术语和概念 A note is a graphical symbol for rendering constraints or comments attached to an element or a collection of elements. Graphically, a note is rendered as a

 Other Features其它特征 Plain, unadorned dependencies, generalizations, and associations with names, multiplicities, and roles are the most common features you’ll need when creating abst

 Associations联合Anassociationis a structural relationship that specifies that objects of one thing are connected to objects of another. Given an association connecting two classes, yo

When you model relationships in the UML,lUse dependencies only when the relationship you are modeling is not structural.lUse generalization only when you have an“is-a-kind-of” rela

 Modeling Nonsoftware Things构建非软件事物模型 Sometimes, the things you model may never have an analog in software. For example, the people who send invoices and the robots that automatically pack

Key AbstractionsIn Java, the applet for printing“Hello, World!” in a Web browser is quite simple:import java.awt.Graphics;class HelloWorld extends java.applet.Applet {  public void p

Mechanisms机制The hardest part of mastering a library as rich as Java’s is learning how its parts work together. For example, how does HelloWorld‘spaint operation get invoked? What operation

Getting Started开始 Modeling a system involves identifying the things that are important to your particular view. These things form the vocabulary of the system you are modeling. For example,

 The UML is a Language for Specifying    In this context, specifying means building models that are precise, unambiguous, and complete. In particular, the UML addresses the specification of al

The UML Is a Language    A language provides a vocabulary and the rules for combining words in that vocabulary for the purpose of communication. Amodeling language is a language whose vocabula