首先看源码：

#!/usr/bin/python # -*- coding : utf-8 -*- """ @author: Diogenes Augusto Fernandes Herminio <diofeher@gmail.com> https://gist.github.com/420905#file_builder_python.py """ # Director class Director(object): def __init__(self): self.builder = None def construct_building(self): self.builder.new_building() self.builder.build_floor() self.builder.build_size() def get_building(self): return self.builder.building # Abstract Builder class Builder(object): def __init__(self): self.building = None def new_building(self): self.building = Building() def build_floor(self): raise NotImplementedError def build_size(self): raise NotImplementedError # Concrete Builder class BuilderHouse(Builder): def build_floor(self): self.building.floor = 'One' def build_size(self): self.building.size = 'Big' class BuilderFlat(Builder): def build_floor(self): self.building.floor = 'More than One' def build_size(self): self.building.size = 'Small' # Product class Building(object): def __init__(self): self.floor = None self.size = None def __repr__(self): return 'Floor: {0.floor} | Size: {0.size}'.format(self) # Client if __name__ == "__main__": director = Director() director.builder = BuilderHouse() director.construct_building() building = director.get_building() print(building) director.builder = BuilderFlat() director.construct_building() building = director.get_building() print(building) ### OUTPUT ### # Floor: One | Size: Big # Floor: More than One | Size: Small

大致的类图如下：

建造者类BuilderHouse和BuilderFloor都派生自建造者Builder，分贝可以生成house和floor的对象。Director中持有Builder的引用，具体是那种Builder可以有client指定。

Director的construct_building方法，会生成新的Building对象，并用对应的构建者类对building的floor和size进行初始化。