UML Unified Modeling Language

1、UML The definition of

​ Unified modeling language (Unified Modeling Language,UML) It starts with 1997 One year OMG standard , It's for object-oriented Describe the products of the system 、 visualization and Organization A standard language for documentation , It's the third generation of generic modeling and specification languages .UML It's a modeling tool for object-oriented design , Independent of any specific programming language .

​ When it comes to software development , System designer / The system architect gives UML The design , Programmers will be based on UML Design drawings are coded / Development .

2、 Modeling tools

• IBM Rational Rose
• starUML
• MS Visio( The best thing is to draw a flow chart )
• .....

3、 common UML chart

1. Class diagram （Class Diagram）： Information describing a class , And the relationship information between classes .
2. Use case diagram （Use Case Diagram）: Standing in the system user （ System roles ） Of What are the functions of the angle analysis system .
3. Sequence diagram （Sequence Diagram）： Describe the execution of the program , method , The return value of the method .

4、 Class diagram （Class Diagram）

1) Definition of class diagram

​ Class diagram （Class Diagram）： Information describing a class , And the relationship information between classes .

2) Draw a class diagram

• Usually in Rational Rose The tool Logical View Implementation class diagram under directory

• Structure directories are usually created

  

• Create a class diagram

  

  

• Write notes

  

  

• Create properties

  

  

• Create method （）

  

• result

  

3) Six relationships

​ (1) Generalization relation （is a：Cat is a Animal--》 Inherit ）： Classes and classes 、 Interfaces and interface inheritance .

​ (2) Realization relationship （like a：Cooker like a FoodMenu）： Class implementation interface

​ (3) Connections （has a：Programmer has a Computer）

​ (4) Aggregate relationship

​ Aggregation relationship describes the relationship between whole and part , Aggregation is a special relationship . For example, there are multiple students in a classroom , The relationship between the classroom and students is the relationship between the whole and the part , In an aggregate relationship , The whole life cycle doesn't determine the part life cycle , for example ： The classroom is gone , The students are still , Or the students are gone , The classroom is still there .

​ (5) synthetic relation

​ Combinatorial relationship can be regarded as a special aggregation relationship , The whole life cycle determines the part life cycle , The part is attached to the whole , It's impossible for a part to leave the whole “ Alive ”. For example, the relationship between people and limbs .

​ (6) Dependency relationship

​ Dependency is the weakest of all relationships , This relationship is generally reflected between classes and local variables .

5、 Use case diagram （Use Case Diagram）

1) Definition of use case diagram

​ Standing in the system user （ System roles ） What are the functions of the system .

​ When implementing use case diagrams , We need to extract system roles first .

2) Implementation use case diagram

6、 Sequence diagram （sequence diagram）

1) Definition of sequence diagram

​ The method calling process is described in the sequence diagram , Procedure execution flow , And the return value at the end of method execution .

2) Implementation sequence diagram

​ The sequence diagram is usually in Rational Rose Of Logical view To realize

​ An example in the use case diagram corresponds to a sequence diagram in the sequence diagram . How does the timing diagram describe a function , What is the process .

3) notes

• Villain ： The initiator of the action
• rectangular / Small circle ： object
• Implement arrow ： call
• Dashed arrow ： return
• Columnar ： Object lifecycle , The column cannot be broken , It can't be broken in the same process .
• Fold back line ： The current class is invoked by other methods in its middle note. .