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建造者模式

前序

小菜和大鸟两人出去吃夜宵,大鸟要了份炒饭,小菜要了份炒面。炒完后大鸟看到炒面感觉不错,于是也叫了一份。大鸟尝后感觉淡而无味,于是便问小菜:“为什么你的炒面好吃,而我再要的炒面却没有放盐?这好吃不好吃是由谁决定的?”小菜答道:“当然是烧菜的人,他感觉好,就是一盘好面,要是心情不好,或者粗心大意,就是一盘垃圾。”“:)好,那再想想,老麦老肯他们的产品,味道是由什么决定的?”“我知道,那是由他们的工作流程决定的,由于他们制定了非常规范的工作流程,原料放多少,加热几分钟,都有严格规定,估计放多少盐都是用克来计量的。而这个工作流程是在所有的门店都必须要遵照执行的,所以我们吃到的东西不管在哪在什么时候味道都一样。这里我们要吃的食物都依赖工作流程。”

于是大鸟出题让小菜实现一个画小人的程序。

建造小人第一版

#include <stdio.h>

 

class Graphics

{

public:

       void DrawEllipse(int x1,int y1,int x2,int y2)

       {

              printf("DrawEllipse %d,%d,%d,%d\n",x1,y1,x2,y2);

       }

      

       void DrawRectangle(int x1,int y1,int x2,int y2)

       {

              printf("DrawRectangle %d,%d,%d,%d\n",x1,y1,x2,y2);

       }

      

       void DrawLine(int x1,int y1,int x2,int y2)

       {

              printf("DrawLine %d,%d,%d,%d\n",x1,y1,x2,y2);

       }

};

 

class PersonThinBuilder

{

public:

       PersonThinBuilder(Graphics _g) : g(_g){}

      

       void Build()

       {

              g.DrawEllipse(50,20,30,30);

              g.DrawRectangle(60,50,10,50);

              g.DrawLine(60,50,40,100);

              g.DrawLine(70,50,90,100);

              g.DrawLine(60,100,45,150);

              g.DrawLine(70,100,85,150);

       }

protected:

       Graphics g;

};

 

class PersonFatBuilder

{

public:

       PersonFatBuilder(Graphics _g) : g(_g){}

      

       void Build()

       {

              g.DrawEllipse(50,20,30,30);

              g.DrawEllipse(60,50,10,50);

              g.DrawLine(60,50,40,100);

              g.DrawLine(70,50,90,100);

              g.DrawLine(60,100,45,150);

              g.DrawLine(70,100,85,150);

       }

protected:

       Graphics g;

};

 

int main()

{

       Graphics gThin,gFat;

      

       PersonThinBuilder* ptb = new PersonThinBuilder(gThin);

       ptb->Build();

      

       PersonFatBuilder* pfb = new PersonFatBuilder(gFat);

       pfb->Build();

      

       delete ptb;

       delete pfb;

       return 0;

}

“炒面忘记放盐的问题依然没有解决。比如我们现在需要你加一个高个的小人,你会不会因为编程不注意,又让他缺胳膊少腿呢?”

“是呀,最好的办法是规定,凡是建造小人,都必须要有头和身体,以及两收两脚。”

建造者模式

将产品的内部表象和产品的生成过程分割开来,从而使一个建造过程生成具有不同的内部表象的产品对象。建造模式使得产品内部表象可以独立的变化,客户不必知道产品内部组成的细节。建造模式可以强制实行一种分步骤进行的建造过程。

实现方式(UML类图)


实现代码

#include <stdio.h>

 

class Graphics

{

public:

       void DrawEllipse(int x1,int y1,int x2,int y2)

       {

              printf("DrawEllipse %d,%d,%d,%d\n",x1,y1,x2,y2);

       }

      

       void DrawRectangle(int x1,int y1,int x2,int y2)

       {

              printf("DrawRectangle %d,%d,%d,%d\n",x1,y1,x2,y2);

       }

      

       void DrawLine(int x1,int y1,int x2,int y2)

       {

              printf("DrawLine %d,%d,%d,%d\n",x1,y1,x2,y2);

       }

};

 

class PersonBuilder

{

public:

       PersonBuilder(Graphics _g) : g(_g){}

      

       virtual void BuildHead()=0;

       virtual void BuildBody()=0;

       virtual void BuildArmLeft()=0;

       virtual void BuildArmRight()=0;

       virtual void BuildLegLeft()=0;

       virtual void BuildLegRight()=0;

protected:

       Graphics g;

};

 

class PersonThinBuilder : public PersonBuilder

{

public:

       PersonThinBuilder(Graphics g) : PersonBuilder(g){}

      

       virtual void BuildHead()

       {

              g.DrawEllipse(50,20,30,30);

       }

      

       virtual void BuildBody()

       {

              g.DrawRectangle(60,50,10,50);

       }

      

       virtual void BuildArmLeft()

       {

              g.DrawLine(60,50,40,100);

       }

      

       virtual void BuildArmRight()

       {

              g.DrawLine(70,50,90,100);

       }

      

       virtual void BuildLegLeft()

       {

              g.DrawLine(60,100,45,150);

       }

      

       virtual void BuildLegRight()

       {

              g.DrawLine(70,100,85,150);

       }

};

 

class PersonFatBuilder : public PersonBuilder

{

public:

       PersonFatBuilder(Graphics g) : PersonBuilder(g){}

      

       virtual void BuildHead()

       {

              g.DrawEllipse(50,20,30,30);

       }

      

       virtual void BuildBody()

       {

              g.DrawEllipse(60,50,10,50);

       }

      

       virtual void BuildArmLeft()

       {

              g.DrawLine(60,50,40,100);

       }

      

       virtual void BuildArmRight()

       {

              g.DrawLine(70,50,90,100);

       }

      

       virtual void BuildLegLeft()

       {

              g.DrawLine(60,100,45,150);

       }

      

       virtual void BuildLegRight()

       {

              g.DrawLine(70,100,85,150);

       }

};

 

class PersonDirector

{

public:

       PersonDirector(PersonBuilder* _pb) : pb(_pb){}

      

       void CreatePerson()

       {

              pb->BuildHead();

              pb->BuildBody();

              pb->BuildArmLeft();

              pb->BuildArmRight();

              pb->BuildLegLeft();

              pb->BuildLegRight();

       }

protected:

       PersonBuilder* pb;

};

 

int main()

{

       Graphics gThin,gFat;

      

       PersonThinBuilder* ptb = new PersonThinBuilder(gThin);

       PersonDirector* pdThin = new PersonDirector(ptb);

       pdThin->CreatePerson();

      

       PersonFatBuilder* pfb = new PersonFatBuilder(gFat);

       PersonDirector* pdFat = new PersonDirector(pfb);

       pdFat->CreatePerson();

      

       delete ptb;

       delete pdThin;

       delete pfb;

       delete pdFat;

       return 0;

}

运行结果



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posted on 2011-06-02 17:34 lwch 阅读(1827) 评论(1)  编辑 收藏 引用 所属分类: 设计模式

评论:
# re: 建造者模式 2011-06-12 22:11 | jc_ontheroad
学习设计模式。  回复  更多评论
  

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