深入解析Python设计模式编程中建造者模式的使用

建造者模式：将一个复杂对象的构建与他的表示分离，使得同样的构建过程可以创建不同的表示。

基本思想
某类产品的构建由很多复杂组件组成；
这些组件中的某些细节不同，构建出的产品表象会略有不同；
通过一个指挥者按照产品的创建步骤来一步步执行产品的创建；
当需要创建不同的产品时，只需要派生一个具体的建造者，重写相应的组件构建方法即可。

代码结构

class Builder(object):
  """基类"""
  def Part1(self):
    # 不同类型的产品，该步骤的细节可能不同
    raise NotImplementedError()

  def Part2(self):
    # 不同类型的产品，该步骤的细节可能不同
    raise NotImplementedError()

class Builder1(Builder):
  """派生类，生产builder1类型的产品"""
  def Part1(self):
    print 'builder1 Part1'

  def Part2(self):
    print 'builder1 Part2'

class Builder2(Builder):
  """派生类，生产builder2类型的产品"""
  def Part1(self):
    print 'builder2 Part1'

  def Part2(self):
    print 'builder2 Part2'

class Director(object):
  """指挥者，负责组织产品的构建过程"""
  def Build(self, builder):
    builder.Part1()
    builder.Part2()

def client():
  director = Director()
  director.Build(Builder1())
  director.Build(Builder2())

这里有一个疑问，指挥者这个角色有什么用呢。感觉除了增加client的调用负担外，似乎没什么用处。为什么不把产品构建过程放在Builder基类中呢，像下面这样：

class Builder(object):
  """基类"""
  def Part1(self):
    raise NotImplementedError()

  def Part2(self):
    raise NotImplementedError()

  def Build(self):
    self.Part1()
    self.Part2()

class Builder1(Builder):
  def Part1(self):
    print 'builder1 Part1'

  def Part2(self):
    print 'builder1 Part2'

class Builder2(Builder):
  def Part1(self):
    print 'builder2 Part1'

  def Part2(self):
    print 'builder2 Part2'

def client():
  Builder1().Build()
  Builder2().Build()

没错，上面就是典型的模板方法模式的实现套路，回顾一下模板方法模式的定义： > 模板方法模式：定义一个工作流或算法的基本骨架，而将一些特定步骤的实现延迟到子类中。

模板方法模式更多的关注于算法流程，而建造者模式更多的关注于复杂对象的创建，模板模式应用场景比建造者模式更多一些，写起来也更自然一些。

类图

实例

#encoding=utf-8 
# 
#by panda 
#建造者模式 
 
 
def printInfo(info): 
  print unicode(info, 'utf-8').encode('gbk') 
 
#建造者基类 
class PersonBuilder(): 
  def BuildHead(self): 
    pass 
   
  def BuildBody(self): 
    pass 
   
  def BuildArm(self): 
    pass 
 
  def BuildLeg(self): 
    pass 
   
#胖子 
class PersonFatBuilder(PersonBuilder): 
  type = '胖子' 
  def BuildHead(self): 
    printInfo("构建%s的头" % self.type) 
   
  def BuildBody(self): 
    printInfo("构建%s的身体" % self.type) 
   
  def BuildArm(self): 
    printInfo("构建%s的手" % self.type) 
 
  def BuildLeg(self): 
    printInfo("构建%s的脚" % self.type) 
   
 
#瘦子 
class PersonThinBuilder(PersonBuilder): 
  type = '瘦子' 
  def BuildHead(self): 
    printInfo("构建%s的头" % self.type) 
   
  def BuildBody(self): 
    printInfo("构建%s的身体" % self.type) 
   
  def BuildArm(self): 
    printInfo("构建%s的手" % self.type) 
 
  def BuildLeg(self): 
    printInfo("构建%s的脚" % self.type) 
 
#指挥者 
class PersonDirector(): 
  pb = None; 
  def __init__(self, pb): 
    self.pb = pb 
   
  def CreatePereson(self): 
    self.pb.BuildHead() 
    self.pb.BuildBody() 
    self.pb.BuildArm() 
    self.pb.BuildLeg() 
 
def clientUI(): 
  pb = PersonThinBuilder() 
  pd = PersonDirector(pb) 
  pd.CreatePereson() 
   
  pb = PersonFatBuilder() 
  pd = PersonDirector(pb) 
  pd.CreatePereson() 
  return 
 
 
if __name__ == '__main__': 
  clientUI(); 

Statement of this Website

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress images for free

Clothoff.io

AI clothes remover

AI Hentai Generator

Generate AI Hentai for free.

Show More

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)

2 weeks ago By 尊渡假赌尊渡假赌尊渡假赌

Hello Kitty Island Adventure: How To Get Giant Seeds

1 months ago By 尊渡假赌尊渡假赌尊渡假赌

How Long Does It Take To Beat Split Fiction?

4 weeks ago By DDD

R.E.P.O. Save File Location: Where Is It & How to Protect It?

4 weeks ago By DDD

Two Point Museum: All Exhibits And Where To Find Them

1 months ago By 尊渡假赌尊渡假赌尊渡假赌

Show More

Hot Tools

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Show More

Hot Topics

Where is the login entrance for gmail email?

7378

15

Java Tutorial

1628

14

CakePHP Tutorial

1357

52

Laravel Tutorial

1267

25

PHP Tutorial

1216

29

Show More