访问者模式2.doc

设计模式访问者模式 访问者模式（Visitor）是一种分离对象数据结构与行为的方法，通过这种分离，可以为一个已存在的类或类群增加新的操作而无需为它们作任何修改。 结构图为：公司的人事评估需要人事部访问每一个员工列表，逐个对员工作出评估，人事部有两个访问者，一个访问者评估员工假期，另一个评估员工薪资。实现代码： /Element.hclassVisitor;classElementpublic:Element();virtualElement();virtualvoidAccept(Visitor*)=0;friendclassVisitor;/Element.cpp#includestdafx.h#includeElement.hElement:Element()Element:Element()/Employee.h#includeElement.hclassEmployee:publicElementpublic:Employee(char*,double,int);virtualEmployee();voidAccept(Visitor*);char*GetName();doubleGetSalary();intGetVacationDays();voidSetSalary(double);voidSetVacationDays(int);private:char*m_pName;doublem_dSalary;intm_nVacationDays;/Employee.cpp#includestdafx.h#includeEmployee.h#includeVisitor.hEmployee:Employee(char*pName,doubledSalary,intnVacationDays)m_pName=pName;m_dSalary=dSalary;m_nVacationDays=nVacationDays;Employee:Employee()voidEmployee:Accept(Visitor*pVisitor)pVisitor-Visit(this);char*Employee:GetName()returnm_pName;doubleEmployee:GetSalary()returnm_dSalary;intEmployee:GetVacationDays()returnm_nVacationDays;voidEmployee:SetSalary(doubledSalary)m_dSalary=dSalary;voidEmployee:SetVacationDays(intnVacationDays)m_nVacationDays=nVacationDays;/Visitor.hclassElement;classVisitorpublic:virtualVisitor()=0;virtualvoidVisit(Element*)=0;protected:Visitor();/Visitor.cpp#includestdafx.h#includeVisitor.hVisitor:Visitor()Visitor:Visitor() /IncomeVisitor.h#includeVisitor.hclassIncomeVisitor:publicVisitorpublic:IncomeVisitor();virtualIncomeVisitor();voidVisit(Element*);/IncomeVisitor.cpp#includestdafx.h#includeIncomeVisitor.h#includeEmployee.h#includeusingnamespacestd;IncomeVisitor:IncomeVisitor() IncomeVisitor:IncomeVisitor() voidIncomeVisitor:Visit(Element*pElement)/访问者提高员工10%的薪资Employee*pEmployee=static_cast(pElement);doubledSalary=pEmployee-GetSalary();pEmployee-SetSalary(dSalary*1.10);cout员工GetName()的新工资是：GetSalary()元endl;/VacationVisitor.h#includeVisitor.hclassVacationVisitor:publicVisitorpublic:VacationVisitor();virtualVacationVisitor();voidVisit(Element*);/VacationVisitor.cpp#includestdafx.h#includeVacationVisitor.h#includeEmployee.h#includeusingnamespacestd;VacationVisitor:VacationVisitor() VacationVisitor:VacationVisitor() voidVacationVisitor:Visit(Element*pElement)/访问者为员工增加3天假期Employee*pEmployee=static_cast(pElement);intnVacationDays=pEmployee-GetVacationDays();pEmployee-SetVacationDays(nVacationDays+3);cout员工GetName()的新假期是：GetVacationDays()天endl;/main.cpp#includestdafx.h#includeEmployee.h#includeIncomeVisitor.h#includeVacationVisitor.hintmain(intargc,char*argv)Element*pEmployeeA=newEmployee(张三,10000.00,10);Element*pEmployeeB=newEmployee(李四,15000.00,20);IncomeVisitorincomeV;VacationVisitorvacationV;incomeV.Visit(pEmployeeA);vacationV.Vi