Строитель (шаблон проектирования)

Строитель
Builder
Тип	порождающий
Описан в Design Patterns	Да

Строитель (англ. Builder) — порождающий шаблон проектирования.

Цель

Отделяет конструирование сложного объекта от его представления, так что в результате одного и того же процесса конструирования могут получаться разные представления.

Плюсы

• позволяет изменять внутреннее представление продукта;
• изолирует код, реализующий конструирование и представление;
• дает более тонкий контроль над процессом конструирования.

Применение

• алгоритм создания сложного объекта не должен зависеть от того, из каких частей состоит объект и как они стыкуются между собой;
• процесс конструирования должен обеспечивать различные представления конструируемого объекта.

Применение

Объекты "моникер" в Microsoft COM есть Строители, инициализируемые строкой. Более того, для их создания используется другой Строитель - MkParseDisplayNameEx, который определяет по строке класс моникера, создает моникер и инициализирует его этой же строкой.

Один из этих объектов - URL Moniker - используется для всей загрузки страниц, вложений и документов в Microsoft Internet Explorer.

Примеры

Пример на Java

Исходный текст на языке Java

 /** "Product" */
 class Pizza {
    private String dough = "";
    private String sauce = "";
    private String topping = "";

    public void setDough(String dough)     { this.dough = dough; }
    public void setSauce(String sauce)     { this.sauce = sauce; }
    public void setTopping(String topping) { this.topping = topping; }
 }


 /** "Abstract Builder" */
 abstract class PizzaBuilder {
    protected Pizza pizza;

    public Pizza getPizza() { return pizza; }
    public void createNewPizzaProduct() { pizza = new Pizza(); }

    public abstract void buildDough();
    public abstract void buildSauce();
    public abstract void buildTopping();
 }

 /** "ConcreteBuilder" */
 class HawaiianPizzaBuilder extends PizzaBuilder {
    public void buildDough()   { pizza.setDough("cross"); }
    public void buildSauce()   { pizza.setSauce("mild"); }
    public void buildTopping() { pizza.setTopping("ham+pineapple"); }
 }

 /** "ConcreteBuilder" */
 class SpicyPizzaBuilder extends PizzaBuilder {
    public void buildDough()   { pizza.setDough("pan baked"); }
    public void buildSauce()   { pizza.setSauce("hot"); }
    public void buildTopping() { pizza.setTopping("pepperoni+salami"); }
 }


 /** "Director" */
 class Waiter {
    private PizzaBuilder pizzaBuilder;

    public void setPizzaBuilder(PizzaBuilder pb) { pizzaBuilder = pb; }
    public Pizza getPizza() { return pizzaBuilder.getPizza(); }

    public void constructPizza() {
       pizzaBuilder.createNewPizzaProduct();
       pizzaBuilder.buildDough();
       pizzaBuilder.buildSauce();
       pizzaBuilder.buildTopping();
    }
 }


 /** A customer ordering a pizza. */
 class BuilderExample {
    public static void main(String[] args) {
        Waiter waiter = new Waiter();
        PizzaBuilder hawaiian_pizzabuilder = new HawaiianPizzaBuilder();
        PizzaBuilder spicy_pizzabuilder = new SpicyPizzaBuilder();

        waiter.setPizzaBuilder( hawaiian_pizzabuilder );
        waiter.constructPizza();

        Pizza pizza = waiter.getPizza();
    }
 }

Пример на С#

Исходный текст на языке C#

 using System;
 using System.Collections.Generic;

 namespace Builder
 {

  public class MainApp
  {
    public static void Main()
    {
      // Create director and builders
      Director director = new Director();

      Builder b1 = new ConcreteBuilder1();
      Builder b2 = new ConcreteBuilder2();

      // Construct two products
      director.Construct(b1);
      Product p1 = b1.GetResult();
      p1.Show();

      director.Construct(b2);
      Product p2 = b2.GetResult();
      p2.Show();

      // Wait for user
      Console.Read();
    }
  }

  // "Director"

  class Director
  {
    // Builder uses a complex series of steps
    public void Construct(Builder builder)
    {
      builder.BuildPartA();
      builder.BuildPartB();
    }
  }

  // "Builder"

  abstract class Builder
  {
    public abstract void BuildPartA();
    public abstract void BuildPartB();
    public abstract Product GetResult();
  }

  // "ConcreteBuilder1"

  class ConcreteBuilder1 : Builder
  {
    private readonly Product product = new Product();

    public override void BuildPartA()
    {
      product.Add("PartA");
    }

    public override void BuildPartB()
    {
      product.Add("PartB");
    }

    public override Product GetResult()
    {
      return product;
    }
  }

  // "ConcreteBuilder2"

  class ConcreteBuilder2 : Builder
  {
    private readonly Product product = new Product();

    public override void BuildPartA()
    {
      product.Add("PartX");
    }

    public override void BuildPartB()
    {
      product.Add("PartY");
    }

    public override Product GetResult()
    {
      return product;
    }
  }

  // "Product"

  class Product
  {
    private readonly List<string> parts = new List<string>();

    public void Add(string part)
    {
      parts.Add(part);
    }

    public void Show()
    {
      Console.WriteLine("\nProduct Parts -------");
      foreach (string part in parts)
        Console.WriteLine(part);
    }
  }
 }

Пример на C++

Исходный текст на языке C++

// Реализация на C++.

#include <iostream>
#include <memory>
#include <string>

// Product
class Pizza
{
private:
    std::string dough;
    std::string sauce;
    std::string topping;
    
public:
    Pizza() { }
    ~Pizza() { }

    void SetDough(const std::string& d) { dough = d; };
    void SetSauce(const std::string& s) { sauce = s; };
    void SetTopping(const std::string& t) { topping = t; }

    void ShowPizza()
    {
        std::cout << " Yummy !!!" << std::endl
        << "Pizza with Dough as " << dough
        << ", Sauce as " << sauce
        << " and Topping as " << topping
        << " !!! " << std::endl;
    }
};

// Abstract Builder
class PizzaBuilder
{
protected:
    std::auto_ptr<Pizza> pizza;
public:
    PizzaBuilder() {}
    virtual ~PizzaBuilder() {}
    std::auto_ptr<Pizza> GetPizza() { return pizza; }

    void createNewPizzaProduct() { pizza.reset (new Pizza); }

    virtual void buildDough()=0;
    virtual void buildSauce()=0;
    virtual void buildTopping()=0;

};

// ConcreteBuilder
class HawaiianPizzaBuilder : public PizzaBuilder
{
public:
    HawaiianPizzaBuilder() : PizzaBuilder() {}
    ~HawaiianPizzaBuilder(){}

    void buildDough() { pizza->SetDough("cross"); }
    void buildSauce() { pizza->SetSauce("mild"); }
    void buildTopping() { pizza->SetTopping("ham and pineapple"); }
};

// ConcreteBuilder
class SpicyPizzaBuilder : public PizzaBuilder
{
public:
    SpicyPizzaBuilder() : PizzaBuilder() {}
    ~SpicyPizzaBuilder() {}

    void buildDough() { pizza->SetDough("pan baked"); }
    void buildSauce() { pizza->SetSauce("hot"); }
    void buildTopping() { pizza->SetTopping("pepperoni and salami"); }
};

// Director
class Waiter
{
private:
    PizzaBuilder* pizzaBuilder;
public:
    Waiter() : pizzaBuilder(NULL) {}
    ~Waiter() { }
    
    void SetPizzaBuilder(PizzaBuilder* b) { pizzaBuilder = b; }
    std::auto_ptr<Pizza> GetPizza() { return pizzaBuilder->GetPizza(); }
    void ConstructPizza()
    {
        pizzaBuilder->createNewPizzaProduct();
        pizzaBuilder->buildDough();
        pizzaBuilder->buildSauce();
        pizzaBuilder->buildTopping();
    }
};
   
// Клиент заказывает две пиццы.
int main()
{ 
    Waiter waiter;
   
    HawaiianPizzaBuilder hawaiianPizzaBuilder;
    waiter.SetPizzaBuilder (&hawaiianPizzaBuilder);
    waiter.ConstructPizza();
    std::auto_ptr<Pizza> pizza = waiter.GetPizza();
    pizza->ShowPizza();
    
    SpicyPizzaBuilder spicyPizzaBuilder;
    waiter.SetPizzaBuilder(&spicyPizzaBuilder);
    waiter.ConstructPizza();
    pizza = waiter.GetPizza();
    pizza->ShowPizza();
  
    return EXIT_SUCCESS;
}

Пример на JavaScript

Исходный текст на языке JavaScript

// Product
function Pizza() {
	var dublicate = this; // постоянная ссылка на инстанцируемый объект для вызова при любом this
	var dough;
	var sauce;
	var topping;
	
	this.setDough = function(val) {
		dough = val;
	};
	this.setSauce = function(val) {
		sauce = val;
	};
	this.setTopping = function(val) {
		topping = val;
	};
	
	// из-за особенностей языка, геттеры (пусть они нам и не понадобятся) 
	// должны быть определены в той же функции, что и локальные переменные
	this.getDough = function() {
		return dough;
	};
	this.getSauce = function() {
		return sauce;
	};
	this.getTopping = function() {
		return topping;
	};
	
	// мы должны создать метод, изменяющий св-ва уже созданного объекта
	// (см. createNewPizzaProduct)
	this.clear = function() {
		dublicate.setDough(undefined);
		dublicate.setSauce(undefined);
		dublicate.setTopping(undefined);
	};
}

// Abstract Builder
function PizzaBuilder() {
	var pizza = new Pizza();
	
	this.getPizza = function() {
		return pizza;
	};
	this.createNewPizzaProduct = function() {
		// если мы просто поменяем зн-е переменной pizza, то изменение никак
		// не отразится на дочерних классах, т.к. внутри них переменная pizza
		// ссылается на «старую» область памяти
		pizza.clear();
		// если внутри реализаций (HawaiianPizzaBuilder, SpicyPizzaBuilder)
		// мы, вместо переменной pizza, будем использовать метод getPizza,
		// то можно использовать
		// pizza = new Pizza();
		// и метод clear у Pizza не понадобится
	};
	
	this.buildDough = function(val) { };
	this.buildSauce = function(val) { };
	this.buildTopping = function(val) { };
}

// ConcreteBuilder
function HawaiianPizzaBuilder() {
	PizzaBuilder.call(this);
	var pizza = this.getPizza(); // имитация protected
	
	this.buildDough = function() { pizza.setDough("cross"); };
	this.buildSauce = function() { pizza.setSauce("mild"); };
	this.buildTopping = function() { pizza.setTopping("ham+pineapple"); };
}

function SpicyPizzaBuilder() {
	PizzaBuilder.call(this);
	var pizza = this.getPizza();
	
	this.buildDough = function() { pizza.setDough("pan baked"); };
	this.buildSauce = function() { pizza.setSauce("hot"); };
	this.buildTopping = function() { pizza.setTopping("pepperoni+salami"); };
}

// Director
function Waiter() {
	var pizzaBuilder;
	
	this.setPizzaBuilder = function(builder) {
		pizzaBuilder = builder;
	};
	this.getPizza = function() {
		return pizzaBuilder.getPizza();
	};
	
	this.constructPizza = function() {
		pizzaBuilder.createNewPizzaProduct();
		pizzaBuilder.buildDough();
		pizzaBuilder.buildSauce();
		pizzaBuilder.buildTopping();
	};
}

// Клиент заказывает две пиццы
var pizza;
var waiter = new Waiter();

var hawaiianPizzaBuilder = new HawaiianPizzaBuilder();
waiter.setPizzaBuilder( hawaiianPizzaBuilder );
waiter.constructPizza();
pizza = waiter.getPizza();
alert( pizza.getDough() +", "+ pizza.getSauce() +", "+ pizza.getTopping() );

var spicyPizzaBuilder = new SpicyPizzaBuilder();
waiter.setPizzaBuilder( spicyPizzaBuilder );
waiter.constructPizza();
pizza = waiter.getPizza();
alert( pizza.getDough() +", "+ pizza.getSauce() +", "+ pizza.getTopping() );

Пример на Python

Исходный текст на языке Python

#coding: utf-8
class Animal:
    """
    Абстрактное Животное
    """
    legs = 0
    tail = False
    roar = ''

class Mutator:
    """
    Ответственный за размножение
    """
    def mutate(self):
        self.animal = Animal()

class Cat(Mutator):
    """
    Кошка
    """
    def create_legs(self):
        self.animal.legs = 4

    def create_tail(self):
        self.animal.tail = True

    def create_roar(self):
        self.animal.roar = 'meowww!'

class Dog(Mutator):
    """
    Собака
    """
    def create_legs(self):
        self.animal.legs = 4

    def create_tail(self):
        self.animal.tail = True

    def create_roar(self):
        self.animal.roar = 'woffff!'

class AnimalOwner:
    """
    Владелец питомника
    """
    __mutator = ''
    def set_animal(self, mutator):
        self.__mutator = mutator

    def create_an_animal_for_me(self):
        self.__mutator.mutate()
        self.__mutator.create_legs()
        self.__mutator.create_tail()
        self.__mutator.create_roar()

    def get_animal(self):
        return self.__mutator.animal

c = Cat()
d = Dog()
ao = AnimalOwner()
ao.set_animal(c)
ao.create_an_animal_for_me()
animal = ao.get_animal()
print animal.roar #meow!

Пример на PHP5

Исходный текст на языке PHP

<?php

/**
 * Паттерн строитель, оперирует известными "рецептами строительства"
 */

/**
 * Pizza - Базовый объект строительства
 */
class Pizza {
    
    private $_pastry = "";
    private $_sauce = "";
    private $_garniture = "";

    public function setPastry($pastry) {
        $this->_pastry = $pastry;
    }
    public function setSauce($sauce) {
        $this->_sauce = $sauce;
    }
    public function setGarniture($garniture) {
        $this->_garniture = $garniture;
    }
    
}

/**
 * Builder - Абстрактный строитель
 */
abstract class BuilderPizza {
    
    protected $_pizza;

    public function getPizza() {
        return $this->_pizza;
    }
    public function createNewPizza() {
        $this->_pizza = new Pizza ();
    }

    abstract public function buildPastry();
    abstract public function buildSauce();
    abstract public function buildGarniture();
    
}

/**
 * BuilderConcret - Конкретный строитель 1
 */
class BuilderPizzaHawaii extends BuilderPizza {
    
    public function buildPastry() {
        $this->_pizza->setPastry ( "normal" );
    }
    public function buildSauce() {
        $this->_pizza->setSauce ( "soft" );
    }
    public function buildGarniture() {
        $this->_pizza->setGarniture ( "jambon+ananas" );
    }
    
}

/**
 * BuilderConcret - Конкретный строитель 2
 */
class BuilderPizzaSpicy extends BuilderPizza {
    
    public function buildPastry() {
        $this->_pizza->setPastry ( "puff" );
    }
    public function buildSauce() {
        $this->_pizza->setSauce ( "hot" );
    }
    public function buildGarniture() {
        $this->_pizza->setGarniture ( "pepperoni+salami" );
    }
    
}

/**
 * Director - Управляющий класс, запускающий строительство
 */
class Waiter {
    private $_builderPizza;

    public function setBuilderPizza(BuilderPizza $mp)
    {
        $this->_builderPizza = $mp;
    }
    public function getPizza()
    {
        return $this->_builderPizza->getPizza();
    }
    public function constructPizza() {
        $this->_builderPizza->createNewPizza ();
        $this->_builderPizza->buildPastry ();
        $this->_builderPizza->buildSauce ();
        $this->_builderPizza->buildGarniture ();
    }
}

// Инициализация разносчика
$waiter = new Waiter();

// Инициализация доступных продуктов
$builderPizzaHawaii  = new BuilderPizzaHawaii();
$builderPizzaPiquante = new BuilderPizzaSpicy();

// Подготовка и получение продукта
$waiter->setBuilderPizza( $builderPizzaHawaii );
$waiter->constructPizza();
$pizza = $waiter->getPizza();

Пример на Ruby

Исходный текст на языке Ruby

#
# Базовый объект строительства
#
class Pizza
  attr_accessor :pastry, :sauce, :garniture
end

#
# Builder - класс строитель
#
class BuilderPizza
  attr_reader :pizza

  def create_new_pizza
    @pizza = Pizza.new
  end

  def get_pizza
    "Your order. pastry: #{@pizza.pastry}, sauce: #{@pizza.sauce}, garniture: #{@pizza.garniture}"
  end
end

#
# BuilderConcret - Конкретный строитель 1
#
class BuilderPizzaHawaii < BuilderPizza
  def build_pastry  
    @pizza.pastry = 'normal'
  end

  def build_sauce
    @pizza.sauce = 'soft'
  end

  def build_garniture
    @pizza.garniture = 'jambon+ananas'
  end
end

#
# BuilderConcret - Конкретный строитель 2
#
class BuilderPizzaSpicy < BuilderPizza
  def build_pastry
    @pizza.pastry = 'puff'
  end

  def build_sauce
    @pizza.sauce = 'hot'
  end

  def build_garniture
    @pizza.garniture = 'papperoni+salami'
  end
end

#
# Director - Управляющий класс, запускающий строительство
#
class Waiter
  def set_builder_pizza(bp)
    @builder_pizza = bp
  end

  def get_pizza
    @builder_pizza.get_pizza
  end

  def construct_pizza
    @builder_pizza.create_new_pizza
    @builder_pizza.build_pastry
    @builder_pizza.build_sauce
    @builder_pizza.build_garniture
  end
end

waiter = Waiter.new

builder_pizza_hawaii = BuilderPizzaHawaii.new
builder_pizza_spicy  = BuilderPizzaSpicy.new

waiter.set_builder_pizza(builder_pizza_hawaii)
waiter.construct_pizza

puts waiter.get_pizza

Пример на Delphi

Исходный текст на языке Delphi

program BuilderPatternExample;

{$APPTYPE CONSOLE}

uses
  SysUtils;

type
  // Product
  TPizza = class(TObject)
  strict private
    FDough, FSauce, FTopping: string;
  public
    property Dough: string write FDough;
    property Sauce: string write FSauce;
    property Topping: string write FTopping;
    procedure Show();
  end;

  // Abstract Builder
  TPizzaBuilder = class(TObject)
  strict protected
    FPizza: TPizza;
  public
    property Pizza: TPizza read FPizza;

    constructor Create();
    destructor Destroy(); override;

    procedure CreateNewPizzaProduct();
    procedure BuildDough(); virtual; abstract;
    procedure BuildSauce(); virtual; abstract;
    procedure BuildTopping(); virtual; abstract;
  end;

  // Concrete Builder A
  THawaiianPizzaBuilder = class(TPizzaBuilder)
  public
    procedure BuildDough(); override;
    procedure BuildSauce(); override;
    procedure BuildTopping(); override;
  end;

  // Concrete Builder B
  TSpicyPizzaBuilder = class(TPizzaBuilder)
  public
    procedure BuildDough(); override;
    procedure BuildSauce(); override;
    procedure BuildTopping(); override;
  end;

  // Director
  TWaiter = class(TObject)
  strict private
    FPizzaBuilder: TPizzaBuilder;
  public
    property PizzaBuilder: TPizzaBuilder write FPizzaBuilder;

    constructor Create();
    destructor Destroy(); override;
    procedure ConstructPizza();
    function GetPizza(): TPizza;
  end;

{ TPizza }

procedure TPizza.Show();
begin
  WriteLn('Pizza with Dough as ' + FDough + ', sauce as ' + FSauce + ' and Topping as ' + FTopping + '!');
end;

{ TPizzaBuilder }

constructor TPizzaBuilder.Create();
begin
  FPizza := nil;
end;

destructor TPizzaBuilder.Destroy();
begin
  if FPizza <> nil then
    FPizza.Free();
  inherited Destroy();
end;

procedure TPizzaBuilder.CreateNewPizzaProduct();
begin
  if FPizza <> nil then
    FPizza.Free();
  FPizza := TPizza.Create();
end;

{ THawaiianPizzaBuilder }

procedure THawaiianPizzaBuilder.BuildDough();
begin
  if FPizza <> nil then
    FPizza.Dough := 'cross';
end;

procedure THawaiianPizzaBuilder.BuildSauce();
begin
  if FPizza <> nil then
    FPizza.Sauce := 'mild';
end;

procedure THawaiianPizzaBuilder.BuildTopping();
begin
  if FPizza <> nil then
    FPizza.Topping := 'ham and pineapple';
end;

{ TSpicyPizzaBuilder }

procedure TSpicyPizzaBuilder.BuildDough();
begin
  if FPizza <> nil then
    FPizza.Dough := 'pan baked';
end;

procedure TSpicyPizzaBuilder.BuildSauce();
begin
  if FPizza <> nil then
    FPizza.Sauce := 'hot';
end;

procedure TSpicyPizzaBuilder.BuildTopping();
begin
  if FPizza <> nil then
    FPizza.Topping := 'pepperoni and salami';
end;

{ TWaiter }

constructor TWaiter.Create();
begin
  FPizzaBuilder := nil;
end;

destructor TWaiter.Destroy();
begin
  FPizzaBuilder := nil;
  inherited Destroy();
end;

procedure TWaiter.ConstructPizza();
begin
  if FPizzaBuilder <> nil then
  begin
    FPizzaBuilder.CreateNewPizzaProduct();
    FPizzaBuilder.BuildDough();
    FPizzaBuilder.BuildSauce();
    FPizzaBuilder.BuildTopping();
  end;
end;

function TWaiter.GetPizza(): TPizza;
begin
  if FPizzaBuilder <> nil then
    Result := FPizzaBuilder.Pizza
  else
    Result := nil;
end;

var
  Waiter: TWaiter;
  HawaiianPizzaBuilder: THawaiianPizzaBuilder;
  SpicyPizzaBuilder: TSpicyPizzaBuilder;
  Pizza: TPizza;

begin
  HawaiianPizzaBuilder := THawaiianPizzaBuilder.Create();
  SpicyPizzaBuilder := TSpicyPizzaBuilder.Create();
  Waiter := TWaiter.Create();

  // Client has ordered two pizzas
  // Pizza "A"
  Waiter.PizzaBuilder := HawaiianPizzaBuilder;
  Waiter.ConstructPizza();
  Pizza := Waiter.GetPizza();
  Pizza.Show();
  Pizza.Free();
  //Pizza "B"
  Waiter.PizzaBuilder := SpicyPizzaBuilder;
  Waiter.ConstructPizza();
  Pizza := Waiter.GetPizza();
  Pizza.Show();
  Pizza.Free();
  ReadLn;

  Waiter.Free();
  HawaiianPizzaBuilder.Free();
  SpicyPizzaBuilder.Free();
end.

Пример на VB.NET

Исходный текст на языке VB.NET

Imports System.Collections.Generic

Namespace Builder

    Public Class MainApp
        Public Shared Sub Main()
            ' Create director and builders
            Dim director As New Director()

            Dim b1 As Builder = New ConcreteBuilder1()
            Dim b2 As Builder = New ConcreteBuilder2()

            ' Construct two products
            director.Construct(b1)
            Dim p1 As Product = b1.GetResult()
            p1.Show()

            director.Construct(b2)
            Dim p2 As Product = b2.GetResult()
            p2.Show()

            ' Wait for user
            Console.Read()
        End Sub
    End Class

    ' "Director"
    Class Director
        ' Builder uses a complex series of steps
        Public Sub Construct(ByVal builder As Builder)
            builder.BuildPartA()
            builder.BuildPartB()
        End Sub
    End Class

    ' "Builder"
    MustInherit Class Builder
        Public MustOverride Sub BuildPartA()
        Public MustOverride Sub BuildPartB()
        Public MustOverride Function GetResult() As Product
    End Class

    ' "ConcreteBuilder1"
    Class ConcreteBuilder1
        Inherits Builder
        Private ReadOnly product As New Product()

        Public Overrides Sub BuildPartA()
            product.Add("PartA")
        End Sub

        Public Overrides Sub BuildPartB()
            product.Add("PartB")
        End Sub

        Public Overrides Function GetResult() As Product
            Return product
        End Function
    End Class

    ' "ConcreteBuilder2"
    Class ConcreteBuilder2
        Inherits Builder
        Private ReadOnly product As New Product()

        Public Overrides Sub BuildPartA()
            product.Add("PartX")
        End Sub

        Public Overrides Sub BuildPartB()
            product.Add("PartY")
        End Sub

        Public Overrides Function GetResult() As Product
            Return product
        End Function
    End Class

    ' "Product"
    Class Product
        Private ReadOnly parts As New List(Of String)()

        Public Sub Add(ByVal part As String)
            parts.Add(part)
        End Sub

        Public Sub Show()
            Console.WriteLine(vbLf & "Product Parts -------")
            For Each part As String In parts
                Console.WriteLine(part)
            Next
        End Sub
    End Class
End Namespace

Ссылки

• Паттерн Builder (Строитель) — назначение, описание, реализация (С++) и результаты применения