Builder

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小牛编辑

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2023-12-01

Builder Pattern是一种独特的设计模式，有助于使用简单对象构建复杂对象并使用算法方法。这种设计模式属于创作模式的范畴。在此设计模式中，构建器类按步骤构建最终对象。此构建器独立于其他对象。

Builder模式的优点

它提供了清晰的分离，以及构造和表示由类创建的指定对象之间的唯一层。
它可以更好地控制所创建模式的构建过程。
它提供了改变对象内部表示的完美场景。

如何实现构建器模式？

在本节中，我们将学习如何实现构建器模式。

class Director:
   __builder = None
   def setBuilder(self, builder):
      self.__builder = builder
   def getCar(self):
      car = Car()
      # First goes the body
      body = self.__builder.getBody()
      car.setBody(body)
      # Then engine
      engine = self.__builder.getEngine()
      car.setEngine(engine)
      # And four wheels
      i = 0
      while i < 4:
         wheel = self.__builder.getWheel()
			car.attachWheel(wheel)
         i += 1
      return car
# The whole product
class Car:
   def __init__(self):
      self.__wheels = list()
      self.__engine = None
      self.__body = None
   def setBody(self, body):
      self.__body = body
   def attachWheel(self, wheel):
      self.__wheels.append(wheel)
   def setEngine(self, engine):
      self.__engine = engine
   def specification(self):
      print "body: %s" % self.__body.shape
      print "engine horsepower: %d" % self.__engine.horsepower
      print "tire size: %d\'" % self.__wheels[0].size
class Builder:
      def getWheel(self): pass
      def getEngine(self): pass
      def getBody(self): pass
class JeepBuilder(Builder):
   def getWheel(self):
      wheel = Wheel()
      wheel.size = 22
      return wheel
   def getEngine(self):
      engine = Engine()
      engine.horsepower = 400
      return engine
   def getBody(self):
      body = Body()
      body.shape = "SUV"
      return body
# Car parts
class Wheel:
   size = None
class Engine:
   horsepower = None
class Body:
   shape = None
def main():
   jeepBuilder = JeepBuilder() # initializing the class
   director = Director()
   # Build Jeep
   print "Jeep"
   director.setBuilder(jeepBuilder)
   jeep = director.getCar()
   jeep.specification()
   print ""
if __name__ == "__main__":
   main()

输出 (Output)

上述程序生成以下输出 -