??????有了CComObjectRootBase、CComObjectRootEx和線程模型特征類這些基礎原料，CComObject和它的伙伴們便可以自由的發揮它們的想象了。
1.CComObject —— 普通堆對象??????
???下面是精簡的CComObject模板類的定義：??????
template?
<
class
?Base
>
class
?CComObject?:?
public
?Base
{
public
:
????CComObject(
void
*
?
=
?NULL)?
throw
()
????{
????????_pAtlModule
->
Lock();
????}
????
????virtual
?
~
CComObject()?
throw
()
????{
????????FinalRelease();
??????? _pAtlModule
->
Unlock();
????}
????
??? STDMETHOD_(ULONG,?AddRef)()?{
return
?InternalAddRef();}
????STDMETHOD_(ULONG,?Release)()
????{
????????ULONG?l?
=
?InternalRelease();
????????
if
?(l?
==
?
0
)
????????????delete?
this
;
????????
return
?l;
????}
????
????STDMETHOD(QueryInterface)(REFIID?iid,?
void
?
**
?ppvObject)?
throw
()
????{
return
?_InternalQueryInterface(iid,?ppvObject);}
????
????
static
?HRESULT?WINAPI?CreateInstance(CComObject
<
Base
>**
?pp)?
throw
();
};
“普通堆對象”是使用最為頻繁的類，它有如下特征：
（1）在堆中分配內存 —— 計數歸零時用delete銷毀
（2）支持獨立存在的對象 —— 使用InternalXXX來實現IUnknown功能
（3）產生時鎖定服務器，銷毀時解鎖服務器 —— 適用于大多數COM對象
2. CComAggObject —— 被聚合堆對象
template?
<
class
?contained
>
class
?CComAggObject?:
????
public
?IUnknown,
????
public
?CComObjectRootEx
<
?typename?contained::_ThreadModel::ThreadModelNoCS?
>
{
public
:
????CComAggObject(
void
*
?pv)?:?m_contained(pv)
????{
????????_pAtlModule
->
Lock();
????}
????
HRESULT?FinalConstruct()
????{
????????CComObjectRootEx
<
contained::_ThreadModel::ThreadModelNoCS
>
::FinalConstruct();
????????
return
?m_contained.FinalConstruct();
????}
????
void
?FinalRelease()
????{
????????CComObjectRootEx
<
contained::_ThreadModel::ThreadModelNoCS
>
::FinalRelease();
????????m_contained.FinalRelease();
????}
???
?
virtual
?
~
CComAggObject()
????{
???????
?FinalRelease();
????????_pAtlModule
->
Unlock();
????}
????STDMETHOD_(ULONG,?AddRef)()?{
return
?InternalAddRef();}
????STDMETHOD_(ULONG,?Release)()
????{
????????ULONG?l?
=
?InternalRelease();
????????
if
?(l?
==
?
0
)
????????????delete?
this
;
????????
return
?l;
????}
????STDMETHOD(QueryInterface)(REFIID?iid,?
void
?
**
?ppvObject)
????{
????????HRESULT?hRes?
=
?S_OK;
????????
if
?(InlineIsEqualUnknown(iid))
????????{
????????????
*
ppvObject?
=
?(
void
*
)(IUnknown
*
)
this
;
????????????AddRef();
????????}
????????
else
????????????hRes?
=
?m_contained._InternalQueryInterface(iid,?ppvObject);
????????
return
?hRes;
????}
???
?
static
?HRESULT?WINAPI?CreateInstance(LPUNKNOWN?pUnkOuter,?CComAggObject
<
contained
>**
?pp)；
????CComContainedObject
<
contained
>
?m_contained;
};
? CComAggObject有如下特征：
（1）在堆中分配內存
（2）支持被聚合聚合的對象
???????????實現了兩份IUnknown：CComAggObject實現了內部聚合類真正的IUnknown，它管理對象的生存期，并且完成接口查詢（通過contained對象的_InternalQueryInterface）；contained對象實現了具有轉發功能的IUnknown，它將所有的調用轉發給CComAggObject在構造函數中收到的外部IUnknown指針。
（3）產生時鎖定服務器，銷毀時解鎖服務器
3. CComTearOffObject —— tear-off 對象
template?
<
class
?Base
>
class
?CComTearOffObject?:?
public
?Base
{
public
:
????CComTearOffObject(
void
*
?pv)
????{
????????m_pOwner?
=
?reinterpret_cast
<
Base::_OwnerClass
*>
(pv);
????????m_pOwner
->
AddRef();
????}
????
~
CComTearOffObject()
????{
????????FinalRelease();
????????m_pOwner
->
Release();
????}
????STDMETHOD_(ULONG,?AddRef)()?
throw
()?{
return
?InternalAddRef();}
????STDMETHOD_(ULONG,?Release)()?
throw
()
????{
????????ULONG?l?
=
?InternalRelease();
????????
if
?(l?
==
?
0
)
????????????delete?
this
;
????????
return
?l;
????}
????STDMETHOD(QueryInterface)(REFIID?iid,?
void
?
**
?ppvObject)?
throw
()
????{
????????
return
?m_pOwner
->
QueryInterface(iid,?ppvObject);
????}
};
???tear-off對象有如下特征：
（1）在堆中分配內存
（2）支持在ATL組件內部使用的tear-off技術
（3）生成時鎖定父對象，銷毀時解鎖父對象
（4）生命周期由自己管理，接口查詢委托父對象
4. CComObjectStack —— 棧對象
???
template?<class?Base>
class?CComObjectStackEx?:?public?Base
{
public:
????CComObjectStackEx(void*?=?NULL)?
????{?
????????m_hResFinalConstruct?=?FinalConstruct();?
????}
????virtual?~CComObjectStackEx()
????{
??????? FinalRelease();
??? }
????STDMETHOD_(ULONG,?AddRef)()
????{
??????? return?0;
????}
????STDMETHOD_(ULONG,?Release)()
????{
????????return?0;
????}
????STDMETHOD(QueryInterface)(REFIID?iid,?void?**?ppvObject)
????{
????????return?_InternalQueryInterface(iid,?ppvObject);
????}
????HRESULT?m_hResFinalConstruct;
};
???棧對象有如下特征：
（1）內存分配于棧上 —— 不需要對象考慮釋放問題
（2）無引用計數功能
（3）構造時初始化 —— 需要在構造函數調用后檢查m_hResFinalConstruct，以判斷對象是否構造成功
（4）不鎖定服務器
5. CComObjectGlobal —— 全局對象
template?<class?Base>
class?CComObjectGlobal?:?public?Base
{
public:
????CComObjectGlobal(void*?=?NULL)
????{
??????? m_hResFinalConstruct?=?FinalConstruct();
????}
????virtual?~CComObjectGlobal()
????{
?????????????FinalRelease();
????}
????STDMETHOD_(ULONG,?AddRef)()?throw()
????{
????????return?_pAtlModule->Lock();
????}
????STDMETHOD_(ULONG,?Release)()?throw()
????{
????????return?_pAtlModule->Unlock();
????}
????STDMETHOD(QueryInterface)(REFIID?iid,?void?**?ppvObject)?throw()
????{
????????return?_InternalQueryInterface(iid,?ppvObject);
????}
????HRESULT?m_hResFinalConstruct;
};
???
???全局對象有如下特征：
（1）在全局數據區分配內存
（2）初始化時不鎖定服務器，引用計數變化時才鎖定或者解鎖服務器，這使得全局對象可以被用于全局類廠對象，以解決服務器和類廠之間的死鎖問題
（3）構造方式同棧對象
???還有一些其它種類的生存期管理類，如CComObjectNoLock、CComObjectCached、CComPolyObject等等，它們也都有自己獨到的用處，我們也可以根據自己的需要編寫自定義的類。總之CComObjectRootBase、CComObjectRootEx和線程模型特征類就像是積木一樣，我們可以任意的把它們組合成想要的形狀。
posted on 2007-04-06 15:33
michael 閱讀(3714)
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