Shulou(Shulou.com)06/03 Report--

1. The function of class diagram

Class diagram, which is used to describe the various relationships between classes in the system.

2. Elements and relationships in the class diagram

The elements in the class diagram include: classes and interfaces.

The relationships in the class diagram include inheritance (parent-child class relationship), implementation (class-interface relationship), association (global variable, composition / aggregation), dependency (local variable).

2.1. Creation of the class

Public class Person {private Integer id; private String name; public void setName (String name) {this.name=name;} public String getName () {return name;}}

Add properties and actions to the Person class

The property interface of the Person class

Modify the id property

The operation interface of the Person class

Modify setName method

Add parameters to the setName method

Hide several options displayed by the Person class

2.2. Creation of the interface

Modify the display style of the interface

What it looks like after the change

2.3. Class diagram-inheritance relationship

Public abstract class BaseDaoImpl {public void save (Object entity) {} public Object findObject (Object id) {}} public class UserDaoImpl extends BaseDaoImpl {}

2.4. Class diagram-implementation relationship

Public interface UserDao {} public class UserDaoImpl implements UserDao {}

2.5. Class diagram-association relationship

The relationship between classes is actually the relationship between classes.

Association is navigational: that is, a two-way relationship or an one-way relationship.

In Rational Rose, the association has an attribute called Navigable to determine whether to display arrows. Note: arrows are not displayed when Navigable is used on both sides of the association.

2.5.1, aggregation relationship of association (By Ref)

The aggregate relationship represents the relationship between the whole and the part, which can be separated from the whole.

In UML, aggregation relationships are represented by solid lines with hollow diamonds

In Rational Rose, aggregation relationships are implemented by Aggregate and By Reference.

2.5.2. Combinatorial relationship of association (By Value)

It is also the relationship between the whole and the part, but the whole and the part can not be separated; there is no practical significance for the part to leave the whole.

Represented by a solid line with a solid diamond

In Rational Rose, composition relationships are implemented by Aggregate and By Value.

2.6. Class diagram-dependency relationship

If one of the member variables of class An is type B, then there is an "association" between An and B.

If a method of class An accepts local variables of type B, then there is a "dependency" between An and B. Note: "dependency" here is a different concept from Spring's dependency injection, so you should pay attention to the distinction.

Dependency: class A uses another type B, the relationship between An and B is temporary and accidental, but the change of class B will affect A; at the code level, class B is used by class An in a method method as a parameter.

Note: the association here is global, the dependency is local, and the dependency injection in Spring is the association here.

3. Class diagram example

Summary of the class diagram:

Show visibility: display property and method visibility

Show all Attribute: show all attributes

Show all operactions displays all methods

Show operation Signature display method declaration

Show operation Stereotype method type

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