Design mode (Factory mode 1)

Factory mode -- Implementing separation of the creator and caller of the class

Detailed classification:

* Simple Factory mode

* Factory Method mode

* Abstract Factory mode
The basic principles of object-oriented design:

(1) If you have two classes and want to add new functionality, it is best to add new classes instead of modifying the original classes.

(2) If two implementation classes, a is a concrete implementation class, B is also an implementation class,

A-->b,a depends on B, but if B implements an interface, we directly and the interface

Do not have sex with the implementation class. Dependency is shifted from concrete to abstract.

(3). Our class has less to do with other classes, that is, to rely less on other classes,

　　

　　

Design mode (Factory mode 1)