訪問者模式2.doc

設(shè)計(jì)模式訪問者模式 訪問者模式（Visitor）是一種分離對象數(shù)據(jù)結(jié)構(gòu)與行為的方法，通過這種分離，可以為一個已存在的類或類群增加新的操作而無需為它們作任何修改。 結(jié)構(gòu)圖為：公司的人事評估需要人事部訪問每一個員工列表，逐個對員工作出評估，人事部有兩個訪問者，一個訪問者評估員工假期，另一個評估員工薪資。實(shí)現(xiàn)代碼： /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)/訪問者提高員工10%的薪資Employee*pEmployee=static_cast(pElement);doubledSalary=pEmployee-GetSalary();pEmployee-SetSalary(dSalary*1.10);cout員工GetName()的新工資是：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)/訪問者為員工增加3天假期Employee*pEmployee=static_cast(pElement);intnVacationDays=pEmployee-GetVacationDays();pEmployee-SetVacationDays(nVacationDays+3);cout員工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(張三,10000.00,10);Element*pEmployeeB=newEmployee(李四,15000.00,20);IncomeVisitorincomeV;VacationVisitorvacationV;incomeV.Visit(pEmployeeA);vacationV.Vi