设计模式读书笔记：Builder（建造者）

意图：

将一个复杂对象的构建与它的表示分离，使得同样的构建过程可以创建不同的表示。

结构图：来自《23种设计模式 - 郗晓勇》



实现：https://github.com/panshiqu/patterns/tree/master/Builder

Product

#include <iostream>

namespace NS_BUILDER {

class Product {
public:
Product() : _color("none"), _size("none") {}
virtual ~Product() {}

void printSelf(void)
{
std::cout << "Build color: " << _color << " size: " << _size << std::endl;
}

void setColor(std::string color)	{ _color = color; }
void setSize(std::string size)	{ _size = size; }

private:
std::string _color;
std::string _size;
};

} /* namespace NS_BUILDER */

Builder

#include <iostream>

namespace NS_BUILDER {

class Builder {
public:
Builder() {}
virtual ~Builder() {}

virtual void setColor(std::string color) = 0;
virtual void setSize(std::string size) = 0;
};

} /* namespace NS_BUILDER */

ConcreteBuilderA

#include "Product.h"
#include "Builder.h"

namespace NS_BUILDER {

class ConcreteBuilderA : public Builder
{
public:
ConcreteBuilderA()
{
_product = new Product();
}
virtual ~ConcreteBuilderA() {}

virtual void setColor(std::string color)
{
// do nothing
}
virtual void setSize(std::string size)
{
_product->setSize(size);
}
Product *getIgnoreColorProduct(void)
{
return _product;
}

private:
Product *_product;
};

} /* namespace NS_BUILDER */

ConcreteBuilderB

#include "Product.h"
#include "Builder.h"

namespace NS_BUILDER {

class ConcreteBuilderB : public Builder
{
public:
ConcreteBuilderB()
{
_product = new Product();
}
virtual ~ConcreteBuilderB() {}

virtual void setColor(std::string color)
{
_product->setColor(color);
}
virtual void setSize(std::string size)
{
_product->setSize(size);
}
Product *getCareColorProduct(void)
{
return _product;
}

private:
Product *_product;
};

} /* namespace NS_BUILDER */

Director

namespace NS_BUILDER {

class Builder;
class Director {
public:
Director(Builder *builder) : _builder(builder) {}
virtual ~Director() {}
void Build(void);

private:
Builder *_builder;
};

} /* namespace NS_BUILDER */

#include "Director.h"
#include "Builder.h"

namespace NS_BUILDER {

void Director::Build(void)
{
// 可能配置中读出来的属性
_builder->setColor("red");
_builder->setSize("big");
}

} /* namespace NS_BUILDER */

main

#include "Builder/Director.h"
#include "Builder/ConcreteBuilderA.h"
#include "Builder/ConcreteBuilderB.h"
#include "Builder/Product.h"
using namespace NS_BUILDER;
int main(void)
{
ConcreteBuilderB *builder = new ConcreteBuilderB();
Director *director = new Director(builder);
director->Build();

Product *product = builder->getCareColorProduct();
product->printSelf();

delete builder;
delete director;
delete product;
}

附加：