1. 组合模式： 将对象组合成树形结构以表示”部分--整体“的层次结构，组合模式使用户对单个对象和组合对象的使用具有一致性。

需求中是体现部分与整体层次的结构时，希望用户可以忽略组合对象和单个对象的不同，统一地使用组合结构中的所有对象时，就可以用组合模式。

实例：

company.h company.cpp

#ifndef COMPANY_H

#define COMPANY_H

#include <QString>

class Company

{

public:

    Company(QString name);

    void virtual add(Company *c)=0;

    void virtual remove(Company *c)=0;

    void virtual display(QString depth)=0;

    void virtual lineOfDuty()=0;

protected:

    QString name;

};

#endif // COMPANY_H

#include "company.h"

Company::Company(QString name)

{

    this->name = name;

}

concretecompany.h concretecompany.cpp

#ifndef CONCRETECOMPANY_H

#define CONCRETECOMPANY_H

#include "company.h"

#include <QString>

#include <QList>

class ConcreteCompany : public Company

{

public:

    ConcreteCompany(QString name);

    void add(Company *c);

    void remove(Company *c);

    void display(QString depth);

    void lineOfDuty();

protected:

    QList<Company *> *children;

};

#endif // CONCRETECOMPANY_H

#include "concretecompany.h"

#include <QDebug>

ConcreteCompany::ConcreteCompany(QString name) : Company(name)

{

    children = new QList<Company *>();

}

void ConcreteCompany::add(Company *c)

{

    children->push_back(c);

}

void ConcreteCompany::remove(Company *c)

{

    children->removeOne(c);

}

void ConcreteCompany::display(QString depth)

{

    qDebug() << depth << name;

    for(int i=0; i!=children->count(); i++)

    {

        children->at(i)->display( depth + "--");

    }

}

void ConcreteCompany::lineOfDuty()

{

    for(int i=0; i!=children->count(); i++)

    {

        children->at(i)->lineOfDuty();

    }

}

financedepartment.h financedepartment.cpp 财务

#ifndef FINANCEDEPARTMENT_H

#define FINANCEDEPARTMENT_H

#include "company.h"

#include <QString>

class FinanceDepartment : public Company

{

public:

    FinanceDepartment(QString name);

    void add(Company *c);

    void remove(Company *c);

    void display(QString depth);

    void lineOfDuty();

};

#endif // FINANCEDEPARTMENT_H

#include "financedepartment.h"

#include <QDebug>

FinanceDepartment::FinanceDepartment(QString name) : Company(name)

{

}

void FinanceDepartment::add(Company *c)

{}

void FinanceDepartment::remove(Company *c)

{}

void FinanceDepartment::display(QString depth)

{

    qDebug() << depth << name;

}

void FinanceDepartment::lineOfDuty()

{

    qDebug() << "lineOfDuty, money";

}

hrdepartment.h hrdepartment.cpp    HR

#ifndef HRDEPARTMENT_H

#define HRDEPARTMENT_H

#include "company.h"

#include <QString>

class HRDepartment : public Company

{

public:

    HRDepartment(QString name);

    void add(Company *c);

    void remove(Company *c);

    void display(QString depth);

    void lineOfDuty();

};

#endif // HRDEPARTMENT_H

#include "hrdepartment.h"

#include <QDebug>

HRDepartment::HRDepartment(QString name) : Company(name)

{

}

void HRDepartment::add(Company *c)

{}

void HRDepartment::remove(Company *c)

{}

void HRDepartment::display(QString depth)

{

    qDebug() << depth << name;

}

void HRDepartment::lineOfDuty()

{

    qDebug() << "lineOfDuty, HR";

}

main.cpp

#include <QCoreApplication>

#include "concretecompany.h"

#include "hrdepartment.h"

#include "financedepartment.h"

int main(int argc, char *argv[])

{

    ConcreteCompany *root = new ConcreteCompany("beijing_company");

    root->add(new HRDepartment("beijing_HR"));

    root->add(new FinanceDepartment("beijing_money"));

    ConcreteCompany *sub = new ConcreteCompany("hangzhou_company");

    sub->add(new HRDepartment("hangzhou_HR"));

    sub->add(new FinanceDepartment("hangzhou_money"));

    root->add(sub);

    root->display("--");

}