Builder Pattern 建造者模式

Definition

Separate the construction of a complex object from its representation so that the same construction process can create different representations.
将一个复杂对象的构造与它的表示分离，使同样的构建过程可以创建不同的表示，这样的设计模式被称为建造者模式。

Participants

The classes and objects participating in this pattern are:

Builder (VehicleBuilder)

• specifies an abstract interface for creating parts of a Product object

ConcreteBuilder (MotorCycleBuilder, CarBuilder, ScooterBuilder)

• constructs and assembles parts of the product by implementing the Builder interface
• defines and keeps track of the representation it creates
• provides an interface for retrieving the product

Director (Shop)

• constructs an object using the Builder interface

Product (Vehicle)

• represents the complex object under construction. ConcreteBuilder builds the product's internal representation and defines the process by which it's assembled
• includes classes that define the constituent parts, including interfaces for assembling the parts into the final result