1、依据接口编程，设计代理对象的接口
class IPursuit
{
public:
virtual ~IPursuit() {}
virtual void SendFlowers() = 0;
};
2、代理类，也继承代理对象类，保持接口一致class CProxy : public IPursuit
{
public:
CProxy() : m_poIPursuit(NULL) {}
~CProxy()
{
if (m_poIPursuit)
{
delete m_poIPursuit;
m_poIPursuit = NULL;
}
}
void SetPursuit(IPursuit* poIPursuit)
{
//如果有旧的代理，要先删除，否则会造成内存泄漏
if (m_poIPursuit)
{
delete m_poIPursuit;
}
m_poIPursuit = poIPursuit;
}
void SendFlowers()
{
if (m_poIPursuit)
{
printf("Proxy help ");
m_poIPursuit->SendFlowers();
}
}
private:
IPursuit* m_poIPursuit;
}; 代理类实际上啥也没干，只是对同样的函数调用了一手被代理的对象的对应函数，当了一回二传手的角色。这里要注意代理对象由于会在代理中被释放，所以代理的对象一律必须是new出来的，即需在堆上创建的。class CPursuit : public IPursuit
{
public:
CPursuit(TString tstrName) : m_tstrName(tstrName) {}
~CPursuit() {}
void SendFlowers()
{
_tprintf(_T("%s sent flowers to Xiaohong\n"), m_tstrName.c_str());
}
private:
TString m_tstrName;
};另附上TString宏#ifdef UNICODE #define TString std::wstring #else #define TString std::string #endif4、测试示例
void Test()
{
IPursuit* poIXiaoMing = new CPursuit(_T("XiaoMing"));
CProxy oCProxy;
oCProxy.SetPursuit(poIXiaoMing);
oCProxy.SendFlowers();
}5、代理类的应用typedef struct Employee
{
int nID;
TString tstrName;
};
class IEmployee
{
public:
~IEmployee() {}
virtual bool InserttoDB(Employee& stEmployee) = 0;
virtual Employee GetEmployee(int nID) = 0;
};
class CProxy : public IEmployee
{
public:
public:
CProxy() : m_poIEmployee(NULL) {}
~CProxy()
{
if (m_poIEmployee)
{
delete m_poIEmployee;
m_poIEmployee = NULL;
}
}
void SetEmployee(IEmployee* poIEmployee)
{
if (m_poIEmployee)
{
delete m_poIEmployee;
}
m_poIEmployee = poIEmployee;
}
bool InserttoDB(Employee& stEmployee)
{
if (m_poIEmployee)
{
return m_poIEmployee->InserttoDB(stEmployee);
}
return false;
}
Employee GetEmployee(int nID)
{
if (m_poIEmployee)
{
return m_poIEmployee->GetEmployee(nID);
}
Employee stEmployee;
return stEmployee;
}
private:
IEmployee* m_poIEmployee;
};
class CEmployeefromMysql : public IEmployee
{
public:
bool InserttoDB(Employee& stEmployee)
{
_tprintf(_T("Insert employee %s into mysql\n"), stEmployee.tstrName.c_str());
return true;
}
Employee GetEmployee(int nID)
{
Employee stEmployee;
printf("Get an employee from mysql by id %d\n", nID);
return stEmployee;
}
};
class CEmployeefromAccess : public IEmployee
{
public:
bool InserttoDB(Employee& stEmployee)
{
_tprintf(_T("Insert employee %s into access\n"), stEmployee.tstrName.c_str());
return true;
}
Employee GetEmployee(int nID)
{
Employee stEmployee;
printf("Get an employee from access by id %d\n", nID);
return stEmployee;
}
};5.2 使用示例void DataBaseTest()
{
IEmployee* poIEmployee = new CEmployeefromMysql();
CProxy oCProxy;
oCProxy.SetEmployee(poIEmployee);
Employee stEmployee;
stEmployee.nID = 1;
stEmployee.tstrName = _T("Jim");
oCProxy.InserttoDB(stEmployee);
//切换数据库对象
poIEmployee = new CEmployeefromAccess();
oCProxy.SetEmployee(poIEmployee);
oCProxy.InserttoDB(stEmployee);
} 从使用示例中就可以看出，代理类支持客户使用过程中动态切换数据库，这是和工厂模式最大的一点不同，特别适用于在经常需要切换类似对象模式的地方。版权声明：本文为博主原创文章，如需转载请说明转至http://blog.csdn.net/gufeng99
原文地址：http://blog.csdn.net/gufeng99/article/details/46659157
