2014-03-16 星期日 15:26:39 
Builder，继续GOF。
?Separate the construction of a complex object from its representation so that the same construction process can create different representations.
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。
?A reader for the RTF (Rich Text Format) document exchange format should be able to convert RTF to many text formats. The reader might convert RTF documents into plain ASCII text or into a text widget that can be edited interactively. The problem, however, is that the number of possible conversions is open-ended. So it should be easy to add a new conversion without modifying the reader.
?一个RTF（Rich Text Format）文档交换格式的阅读器应能将 RTF转换为多种正文格式。该阅读器可以将 RTF文档转换成普通 ASCII文本或转换成一个能以交互方式编辑的正文窗口组件。但问题在于可能转换的数目是无限的。因此要能够很容易实现新的转换的增加，同时却不改变RTF阅读器。
Use the Builder pattern when
?● the algorithm for creating a complex object should be independent of the parts that make up the object and how they‘re assembled.
?● the construction process must allow different representations for the object that‘s constructed.
在以下情况使用B u i l d e r模式
● 当创建复杂对象的算法应该独立于该对象的组成部分以及它们的装配方式时。
● 当构造过程必须允许被构造的对象有不同的表示时。
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#if 1 class
Product1 { }; class
Product1_Part //上面的RTF的part也可以独立使用 { }; class
Product2 { }; // class Builder class
Builder //抽象基类 { public: virtual
void BuilderPartA() {} //提供缺省实现 virtual
void BuilderPartB() {} virtual
void BuilderPartC() {} protected: Builder() {} }; // class ConcreteBuilder1 class
ConcreteBuilder1 : public
Builder //创建Product1 { public: ConcreteBuilder1() : _product(NULL) {} virtual
void BuilderPartA() {} virtual
void BuilderPartB() {} virtual
void BuilderPartC() {} virtual
Product1* GetProduct1() { return
_product ; } //返回创建的Product1对象 private: Product1 *_product ; }; // class ConcreteBuilder2 class
ConcreteBuilder2 : public
Builder //创建Product2 { public: ConcreteBuilder2() : _product(NULL) {} virtual
void BuilderPartA() {} virtual
void BuilderPartB() {} virtual
void BuilderPartC() {} virtual
Product2* GetProduct2() { return
_product ; } //返回创建的Product2对象 private: Product2 *_product ; }; // class Director class
Director { public: //创建对象(Director并不知道具体创建出来的对象是什么样的，只有调用该函数的client知道) void
Construct(Builder *builder) { builder->BuilderPartA() ; builder->BuilderPartB() ; builder->BuilderPartC() ; } }; //客户端代码： void
Builder_Demo() { Director director ; // 创建第一种对象 ConcreteBuilder1 *pBuilder1 = new
ConcreteBuilder1(); director.Construct(pBuilder1); Product1 *product1 = pBuilder1->GetProduct1(); //Product1_Part *Product1_Part = pBuilder1->BuilderPartA(); //partx 独立使用 pBuilder1->BuilderPartA(); // 创建第二种对象 ConcreteBuilder2 *pBuilder2 = new
ConcreteBuilder2(); director.Construct(pBuilder2); Product2 *product2 = pBuilder2->GetProduct2(); }#endif |
设计模式之五:BUILDER（生成器）—对象创建型模式,布布扣,bubuko.com
原文：http://www.cnblogs.com/freezlz/p/3618817.html