ITK 中的智能指针与对象工厂演示-2

 

6.对象工厂基类

  //MyObjectFactoryBase.h#pragma once#include "MyCreateObjectFunction.h"#include <list>#include <vector>#include <string>////关于对象工厂,参考上面给出的文章,写得很不错,关于泛化对象工厂的原理阐述的很清晰.//泛化对象工厂: http://blog.csdn.net/azure1987/archive/2009/10/27/4732355.aspx////一个 multimap, 用来存储识别对象工厂的信息,及其可以创建的对象的版本信息class OverRideMap;////MyObjectFactoryBase: 工厂基类, ITK 中几乎所有对象都是通过相应的对象工厂创建//MyObjectFactoryBase 中包含一个静态方法 CreateInstance(), 该方法通过已注册的对象工厂创建对象//第一次调用 CreateInstance(), ITK 环境变量路径中所有的 dll 或者 静态库都被加载到当前进程//为了加载环境变量中的动态或静态库到当前进程, ITK 中又使用了其它库, 我将这部分省略掉////1.对象工厂能够在运行时进行版本替换//  在程序中通过变量 m_EnabledFlag 进行控制是否可能创建特定版本的对象实例.//2.使用 multimap 存储识别对象工厂的信息, 这样一个对象工厂中可以有相同 key 的对象//  我们在程序中演示了如何通过设置 m_EnabledFlag 创建不同版本的对象//3.代码中的一些方法如 GetDescription 是用来输出对象工厂信息的//  SetEnableFlag 等是用来控制创建对象的哪一个版本//class MyObjectFactoryBase : public MyObject{public:  typedef MyObjectFactoryBaseSelf;typedef MyObjectSuperclass;typedef MySmartPointer<Self>Pointer;typedef MySmartPointer<const Self>ConstPointer;//virtual const char* GetNameOfClass() const;MyTypeMacro(MyObjectFactoryBase, MyObject);//返回一个名为 classname 的类对象实例//每个被加载的 MyObjectFactoryBase 都会按环境变量中的顺序被询问//一旦有一个工厂成功创建对象并返回, 其余工厂便不再被询问.static MyObject::Pointer CreateInstance(const char* classname);///////////////////////////////注册/注销 对象工厂static void RegisterFactory(MyObjectFactoryBase* );static void UnRegisterFactory(MyObjectFactoryBase*);static void UnRegisterAllFactories();//////////////////////////////返回包含所有已注册的对象工厂的链表static std::list<MyObjectFactoryBase*> GetRegisteredFactories();virtual const char* GetDescription(void) const = 0; //描述该对象工厂//描述对象工厂及其能够创建的对象virtual std::list<std::string> GetClassOverrideNames();virtual std::list<std::string> GetClassOverrideWithNames();virtual std::list<std::string> GetClassOverrideDescriptions();///////////////////////////////m_EnabledFlag:用来控制使用哪一个版本的类来创建对象, 以达到动态替换的目标virtual std::list<bool> GetEnableFlags();//设置/取得 指定版本类的 m_EnabledFlag 标志.virtual void SetEnableFlag(bool flag, const char* className, const char* subclassName);virtual bool GetEnableFlag(const char* className, const char* subclassName);//Disable: 将使对象工厂不能创建该类的任何版本实例virtual void Disable(const char* className);//OverrideInformation: 工厂及对象的版本信息, 及是否可以创建struct OverrideInformation{std::string m_Description;//类的描述std::string m_OverrideWithName;//重载的版本bool m_EnabledFlag;//指示是否可以创建该版本的对象实例.MyCreateObjectFunctionBase::Pointer m_CreateObject;};protected:MyObjectFactoryBase();virtual ~MyObjectFactoryBase();//注册对象工厂, 以及其可以创建的对象版本的信息void RegisterOverride(const char* classOverride,const char* overrideClassName,const char* description,bool enableFlag,MyCreateObjectFunctionBase* createFunction);  ////对象工厂的子类实现 CreateObject 并返回创建的对象的指针，若不支持则返回 0virtual MyObject::Pointer CreateObject(const char* classname );private:MyObjectFactoryBase(const Self&);void operator=(const Self&);static void Initialize();//初始化//一个 multimap: 存储对象工厂及其可以创建的对象的版本信息OverRideMap* m_OverrideMap;//对象工厂列表, 包含指向已经注册的对象工厂的指针static std::list<MyObjectFactoryBase*>* m_RegisteredFactories; }; 

7.Helper 类

  //MyObjectFactory.h#pragma once#include "MyObjectFactoryBase.h"//MyObjectFactory://是一个帮助类(a helper class), 实现 Create() 方法, 用于创建一个对象实例.//对象工厂允许在运行时进行替换.//对象工厂通过运行时类型识别 RTTI 实现.template <class T>class MyObjectFactory : public MyObjectFactoryBase{public:static typename T::Pointer Create(){MyObject::Pointer ret = MyObjectFactory::CreateInstance(typeid(T).name());//ObjectType *GetPointer () const { return m_Pointer; }//取得原始指针, 将其向下类型转换为 T*return dynamic_cast<T*>(ret.GetPointer());}};  

 

8.临界区类实现

  //MyFastMutexLock.h#pragma once//不同的平台需要定义不同的类型,这里只给出 windows32 例子//不同平台在处理时有相应的优化策略, 以保证操作的原子性.#if defined(_WIN32)#include "Windows.h"#include <winbase.h>typedef CRITICAL_SECTION FastMutexType;#endif//为了演示, 完全可以只使用 int 即可, 但无法提供真正的加锁功能#ifndef _WIN32typedef int FastMutexType;#endif//临界区锁类: 在修改临界值时, 对其加锁, 以保证修改的唯一原子性.class MyFastMutexLock{public:typedef MyFastMutexLock   Self;//可以在栈上创建临界区对象, 所以将构造函数与析构函数设为 pubilc.MyFastMutexLock();~MyFastMutexLock();//Lock, 加锁, 使其它任何对象都不能修改被加锁的对象void Lock() const;//Unlock, 解锁void Unlock() const;protected:mutable FastMutexType   m_FastMutexLock;};  

9.MyObject 类的方法实现

   //MyObject.h#pragma once#include "MyMacro.h"#include "MyFastMutexLock.h"#include "MySmartPointer.h"#if defined(_WIN32)  //To get LONG defined  #include "Windows.h"#endif//MyObject 几乎是所有对象的基类, 实现引用计数功能, //代码基本来 ITK 中的 LightObject 类, LightObject 在 ITK 中是最顶层的类.class MyObject{public:typedef MyObjectSelf;typedef MySmartPointer<Self>        Pointer;//包装为智能指针typedef MySmartPointer<const Self>  ConstPointer;//通过对象工厂创建对象的实例static Pointer New();//根据已存在的对象创建一新的对象实例，允许用户创建一个完全相同的对象//这在需要向上类型转换时非常有用***virtual Pointer CreateAnother() const;//使用 New() 的对象, 应该使用 Delete()//Delete() 会调用 UnRegister 减少引用计数//只有当该对象的引用计数减为 0 时才会真正删除对象virtual void Delete();//运行时类型识别, 返回某对象的具体类名.virtual const char *GetNameOfClass() const {return "MyObject";}//Used to avoid dll boundary problems.void* operator new(size_t);void* operator new[](size_t);void operator delete(void*);void operator delete[](void*, size_t);//增加与减少引用计数virtual void Register() const;virtual void UnRegister() const;//返回该类对象实例的引用计数virtual int GetReferenceCount() const {return static_cast<int>(m_ReferenceCount);}//设置该类对象的引用计数值.virtual void SetReferenceCount(int);protected:MyObject() : m_ReferenceCount(1) {}virtual ~MyObject(); //不同的平台, 需要定义不同的类型, 这里只简单使用 int 型. 引用计数.#if (defined(WIN32) || defined(_WIN32))typedef LONG InternalReferenceCountType;#elsetypedef int InternalReferenceCountType;#endif//引用计数mutable InternalReferenceCountType m_ReferenceCount;//mutable intm_ReferenceCount;//临界区锁, 用于对临界区变量加锁mutable MyFastMutexLockm_ReferenceCountLock;private:MyObject(const Self&);         void operator=(const Self&); }; 

10.对象工厂基类实现

  #if defined(_MSC_VER)#pragma warning ( disable : 4786 )#endif#include "MyObjectFactoryBase.h"#include <stdlib.h>#include <ctype.h>#include <string.h>#include <algorithm>#include <map>////////////////////////////////////////////////////////该类用于清除所有已经注册的对象工厂.class CleanUpObjectFactory{public:inline void Use(){}~CleanUpObjectFactory(){MyObjectFactoryBase::UnRegisterAllFactories();}  };//定义一全局静态变量, 在程序生命周期结束时析构, 用于注销所有对象工厂static CleanUpObjectFactory CleanUpObjectFactoryGlobal;//////////////////////////////////////////StringOverMap, 使用 typedef 进行类型定义, 避免出现名字过长的警告.typedef std::multimap<std::string, MyObjectFactoryBase::OverrideInformation>  StringOverMapType;//用于存储 <classID, facotoryInfo>//classID     对象工厂的标识//factoryInfo 该对象工厂的信息, 包含其可以创建的对象的所有版本信息class OverRideMap : public StringOverMapType{};///////////////////////////////////////////////////////静态变量初始化, 已注册的对象工厂链表.std::list<MyObjectFactoryBase*>* MyObjectFactoryBase::m_RegisteredFactories = 0;//构造函数MyObjectFactoryBase::MyObjectFactoryBase(){m_OverrideMap = new OverRideMap;}//析构, 卸载已加载的对象工厂.MyObjectFactoryBase::~MyObjectFactoryBase(){m_OverrideMap->erase(m_OverrideMap->begin(), m_OverrideMap->end());delete m_OverrideMap;}//使用已注册的对象工厂创建类名为 classname 的对象实例.MyObject::Pointer MyObjectFactoryBase::CreateInstance(const char* classname){if( !MyObjectFactoryBase::m_RegisteredFactories ){MyObjectFactoryBase::Initialize();}for( std::list<MyObjectFactoryBase*>::iterator i = m_RegisteredFactories->begin();i != m_RegisteredFactories->end(); ++i ){//遍历已注册的对象列表, 如果某个对象工厂成功创建对象, 则返回MyObject::Pointer newobject = (*i)->CreateObject(classname);if(newobject){newobject->Register();return newobject;}}return 0;}//初始化void MyObjectFactoryBase::Initialize(){//全局静态变量, 用于最后注销所有的对象工厂CleanUpObjectFactoryGlobal.Use();//已经初始化过了, 返回if( MyObjectFactoryBase::m_RegisteredFactories ){return;}MyObjectFactoryBase::m_RegisteredFactories =new std::list<MyObjectFactoryBase*>;}//注册对象工厂, 添加至链表中.void MyObjectFactoryBase::RegisterFactory(MyObjectFactoryBase* factory){//先进行初始化，然后将该对象工厂加入到对象工厂链表中MyObjectFactoryBase::Initialize();MyObjectFactoryBase::m_RegisteredFactories->push_back(factory);factory->Register();}//清除已经清册的名为 factory 的对象工厂void MyObjectFactoryBase::UnRegisterFactory(MyObjectFactoryBase* factory){ if( !MyObjectFactoryBase::m_RegisteredFactories )return;for ( std::list<MyObjectFactoryBase*>::iterator i = m_RegisteredFactories->begin();i != m_RegisteredFactories->end(); ++i ){if ( factory == *i ){factory->UnRegister();m_RegisteredFactories->remove(factory);return;}}}//清除所有已注册的对象工厂, 并删除对象工厂列表void MyObjectFactoryBase::UnRegisterAllFactories(){if ( MyObjectFactoryBase::m_RegisteredFactories ){for ( std::list<MyObjectFactoryBase*>::iteratorf = m_RegisteredFactories->begin();f != m_RegisteredFactories->end(); ++f ){(*f)->UnRegister();}//删除对象工厂链表...delete MyObjectFactoryBase::m_RegisteredFactories;MyObjectFactoryBase::m_RegisteredFactories = 0;}}//返回包含所有已注册的对象工厂的链表...std::list<MyObjectFactoryBase*> MyObjectFactoryBase::GetRegisteredFactories(){return *MyObjectFactoryBase::m_RegisteredFactories;}/////////////////////////////////描述对象工厂及其能够创建的对象std::list<std::string> MyObjectFactoryBase::GetClassOverrideNames(){std::list<std::string> ret;for ( OverRideMap::iterator i = m_OverrideMap->begin();i != m_OverrideMap->end(); ++i ){ret.push_back((*i).first);}return ret;}std::list<std::string> MyObjectFactoryBase::GetClassOverrideWithNames(){std::list<std::string> ret;for ( OverRideMap::iterator i = m_OverrideMap->begin();i != m_OverrideMap->end(); ++i ){ret.push_back((*i).second.m_OverrideWithName);}return ret;}std::list<std::string> MyObjectFactoryBase::GetClassOverrideDescriptions(){ std::list<std::string> ret;for ( OverRideMap::iterator i = m_OverrideMap->begin();i != m_OverrideMap->end(); ++i ){ret.push_back((*i).second.m_Description);}return ret;}//注册对象工厂, 以及其可以创建的对象的版本信息void MyObjectFactoryBase::RegisterOverride(const char* classOverride,const char* subclass,const char* description,bool enableFlag,MyCreateObjectFunctionBase* createFunction){MyObjectFactoryBase::OverrideInformation info;info.m_Description= description;info.m_OverrideWithName = subclass;//具体的子类info.m_EnabledFlag= enableFlag;//是否使用该子类版本info.m_CreateObject= createFunction;m_OverrideMap->insert(OverRideMap::value_type(classOverride, info));}//MyObject::Pointer MyObjectFactoryBase::CreateObject(const char* classname){OverRideMap::iterator start = m_OverrideMap->lower_bound(classname);OverRideMap::iterator end = m_OverrideMap->upper_bound(classname);int m = 0;for ( OverRideMap::iterator i = start; i != end; ++i ){//(*i).second.m_EnabledFlag = true; 则使用该工厂创建该版本的对象实例if ( i != m_OverrideMap->end() && (*i).second.m_EnabledFlag){//调用了 MyCreateObjectFunction::CreateObject();//MyCreateObjectFunction 是用于创建对象的回调函数return (*i).second.m_CreateObject->CreateObject();}}return 0;}/////////////////////////////m_EnabledFlag: 控制对象工厂可以创建的对象版本void MyObjectFactoryBase::SetEnableFlag(bool flag,const char* className,const char* subclassName){OverRideMap::iterator start = m_OverrideMap->lower_bound(className);OverRideMap::iterator end = m_OverrideMap->upper_bound(className);for ( OverRideMap::iterator i = start; i != end; ++i ){if ( (*i).second.m_OverrideWithName == subclassName ){(*i).second.m_EnabledFlag = flag;}}}bool MyObjectFactoryBase::GetEnableFlag(const char* className, const char* subclassName){OverRideMap::iterator start = m_OverrideMap->lower_bound(className);OverRideMap::iterator end = m_OverrideMap->upper_bound(className);for ( OverRideMap::iterator i = start; i != end; ++i ){if ( (*i).second.m_OverrideWithName == subclassName ){return (*i).second.m_EnabledFlag;}}return 0;}void MyObjectFactoryBase::Disable(const char* className){OverRideMap::iterator start = m_OverrideMap->lower_bound(className);OverRideMap::iterator end = m_OverrideMap->upper_bound(className);for ( OverRideMap::iterator i = start; i != end; ++i ){(*i).second.m_EnabledFlag = 0;}}std::list<bool> MyObjectFactoryBase::GetEnableFlags(){std::list<bool> ret;for( OverRideMap::iterator i = m_OverrideMap->begin(); i != m_OverrideMap->end(); ++i){ret.push_back((*i).second.m_EnabledFlag);}return ret;}