COM---类厂

2019-11-08 20:10:51

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问题：为什么要使用类厂？答案：http://www.cppblog.com/ivenher/articles/16460.html

使用类厂的流程：客户调用CoCreateInstance，而CoCreateInstance调用CoGetClassObejct，CoGetClassObejct的作用是调用LoadLibrary寻找指定的COM组件（dll），然后使用GetPRocAddress寻找组件的入口函数，其中DllGetClassObject被调用，这几步不可见，因为微软已经封装好了。问题：CoGetClassObejct要加载dll，但我们并没有传dll路径，如何加载dll的？答案：是通过第一个参数CLSID（组件id，从CreateInstance传过去）去注册表中找到这个组件的DLL路径，然后将DLL加载起来，就可以使用DLL的导出函数DllGetClassObject了，并把CLSID，类厂接口ID传给它，去创建所需的组件，并返回所需的接口。

注意：组件并不等于dll，一个dll可以提供多个组件

接口

//// Iface.h - // Declarations of interfaces, IIDs, and CLSID// shared by the client and the component.//interface IX : IUnknown{ virtual void pascal Fx() = 0 ;};interface IY : IUnknown{ virtual void pascal Fy() = 0 ;};interface IZ : IUnknown{ virtual void pascal Fz() = 0 ;};//// Declaration of GUIDs for interfaces and component.// These constants are defined in GUIDs.cpp.//extern "C" const IID IID_IX ;extern "C" const IID IID_IY ;extern "C" const IID IID_IZ ;extern "C" const CLSID CLSID_Component1 ;

连接客户和组件—GUID

//// GUIDs.cpp// - Defines all IIDs and CLSIDs for the client and the component.// The declaration of these GUIDs is in Iface.h//#include <objbase.h>// {32bb8320-b41b-11cf-a6bb-0080c7b2d682}extern "C" const IID IID_IX = {0x32bb8320, 0xb41b, 0x11cf, {0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, 0x82}} ;// {32bb8321-b41b-11cf-a6bb-0080c7b2d682}extern "C" const IID IID_IY = {0x32bb8321, 0xb41b, 0x11cf, {0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, 0x82}} ;// {32bb8322-b41b-11cf-a6bb-0080c7b2d682}extern "C" const IID IID_IZ = {0x32bb8322, 0xb41b, 0x11cf, {0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, 0x82}} ;// {0c092c21-882c-11cf-a6bb-0080c7b2d682}extern "C" const CLSID CLSID_Component1 = {0x0c092c21, 0x882c, 0x11cf, {0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, 0x82}} ;

组件

//// Cmpnt.cpp//#include <iostream.h>#include <objbase.h>#include "Iface.h" // Interface declarations#include "Registry.h" // Registry helper functions// Trace functionvoid trace(const char* msg) { cout << msg << endl ;}/////////////////////////////////////////////////////////////// 全局变量//static HMODULE g_hModule = NULL ; // DLL module handlestatic long g_cComponents = 0 ; // Count of active componentsstatic long g_cServerLocks = 0 ; // Count of locks// Friendly name of componentconst char g_szFriendlyName[] = "Inside COM, Chapter 7 Example" ;// Version-independent ProgIDconst char g_szVerIndProgID[] = "InsideCOM.Chap07" ;// ProgIDconst char g_szProgID[] = "InsideCOM.Chap07.1" ;/////////////////////////////////////////////////////////////// 组件//class CA : public IX, public IY {public: // IUnknown virtual HRESULT __stdcall QueryInterface(const IID& iid, void** ppv) ; virtual ULONG __stdcall AddRef() ; virtual ULONG __stdcall Release() ; // Interface IX virtual void __stdcall Fx() { cout << "Fx" << endl ;} // Interface IY virtual void __stdcall Fy() { cout << "Fy" << endl ;} // Constructor CA() ; // Destructor ~CA() ;private: // 引用计数 long m_cRef ;} ;//// Constructor//CA::CA() : m_cRef(1){ InterlockedIncrement(&g_cComponents) ; //增加组件计数}//// Destructor//CA::~CA() { InterlockedDecrement(&g_cComponents) ; //减少组件计数 trace("Component:/t/tDestroy self.") ;}//// IUnknown implementation//HRESULT __stdcall CA::QueryInterface(const IID& iid, void** ppv){ if (iid == IID_IUnknown) { *ppv = static_cast<IX*>(this) ; } else if (iid == IID_IX) { *ppv = static_cast<IX*>(this) ; trace("Component:/t/tReturn pointer to IX.") ; } else if (iid == IID_IY) { *ppv = static_cast<IY*>(this) ; trace("Component:/t/tReturn pointer to IY.") ; } else { *ppv = NULL ; return E_NOINTERFACE ; } reinterpret_cast<IUnknown*>(*ppv)->AddRef() ; return S_OK ;}ULONG __stdcall CA::AddRef(){ return InterlockedIncrement(&m_cRef) ;}ULONG __stdcall CA::Release() { if (InterlockedDecrement(&m_cRef) == 0) { delete this ; return 0 ; } return m_cRef ;}/////////////////////////////////////////////////////////////// 类厂，由开发人员决定。创建好类厂后，调用CreateInstance创建组件//class CFactory : public IClassFactory{public: // IUnknown virtual HRESULT __stdcall QueryInterface(const IID& iid, void** ppv) ; virtual ULONG __stdcall AddRef() ; virtual ULONG __stdcall Release() ; //IClassFactory 接口 virtual HRESULT __stdcall CreateInstance(IUnknown* pUnknownOuter, const IID& iid, void** ppv) ; virtual HRESULT __stdcall LockServer(BOOL bLock) ; // Constructor CFactory() : m_cRef(1) {} // Destructor ~CFactory() { trace("Class factory:/t/tDestroy self.") ;}private: long m_cRef ;} ;//// Class factory IUnknown implementation//HRESULT __stdcall CFactory::QueryInterface(const IID& iid, void** ppv){ if ((iid == IID_IUnknown) || (iid == IID_IClassFactory)) { *ppv = static_cast<IClassFactory*>(this) ; } else { *ppv = NULL ; return E_NOINTERFACE ; } reinterpret_cast<IUnknown*>(*ppv)->AddRef() ; return S_OK ;}ULONG __stdcall CFactory::AddRef(){ return InterlockedIncrement(&m_cRef) ;}ULONG __stdcall CFactory::Release() { if (InterlockedDecrement(&m_cRef) == 0) { delete this ; return 0 ; } return m_cRef ;}// IClassFactory implementation//创建一个组件，然后向它查询某个接口//CreateInstance 对其所创建的组件知根知底//pUnknownOuter：同传给CoCreateInstance的IUnknown指针相同，用于聚合组//剩余2个参数与QueryInterface相同HRESULT __stdcall CFactory::CreateInstance(IUnknown* pUnknownOuter, const IID& iid, void** ppv) { trace("Class factory:/t/tCreate component.") ; // Cannot aggregate. if (pUnknownOuter != NULL) { return CLASS_E_NOAGGREGATION ; } // 创建组件 CA* pA = new CA ; if (pA == NULL) { return E_OUTOFMEMORY ; } // 查询接口 HRESULT hr = pA->QueryInterface(iid, ppv) ; // 释放 IUnknown 指针 // (If QueryInterface failed, component will delete itself.) pA->Release() ; return hr ;}// 将服务器保存在内存中，直至使用完毕HRESULT __stdcall CFactory::LockServer(BOOL bLock) { if (bLock) { InterlockedIncrement(&g_cServerLocks) ; //加锁 } else { InterlockedDecrement(&g_cServerLocks) ; //解锁 } return S_OK ;}/////////////////////////////////////////////////////////////// 从DLL中输出的函数////// 被CoFreeUnusedLibraries调用，以询问DLL是否可被卸载掉，节省内存//STDAPI DllCanUnloadNow(){ //当DLL不再提供任何组件，且类厂没有锁 if ((g_cComponents == 0) && (g_cServerLocks == 0)) { return S_OK ; } else { return S_FALSE ; }}//由CoGetClassObject调用，创建客户所请求的类厂//同CreateInstance类似，创建一个组件，然后向它查询某个接口//DllGetClassObject 对其所创建的类厂无所不知//clsid：类厂将要创建的组件的CLSID//iid：类厂中客户希望得到的接口的ID//ppv：保存接口指针STDAPI DllGetClassObject(const CLSID& clsid, const IID& iid, void** ppv){ trace("DllGetClassObject:/tCreate class factory.") ; // 检查客户所请求的类厂组件是否能创建 if (clsid != CLSID_Component1) { return CLASS_E_CLASSNOTAVAILABLE ; } // 用new操作符完成组件的创建 CFactory* pFactory = new CFactory ; // No AddRef in constructor if (pFactory == NULL) { return E_OUTOFMEMORY ; } // 用类厂组件查询客户所请求的接口 HRESULT hr = pFactory->QueryInterface(iid, ppv) ; pFactory->Release() ; return hr ;}//// 在Windows注册表中登记组件//STDAPI DllRegisterServer(){ return RegisterServer(g_hModule, CLSID_Component1, g_szFriendlyName, g_szVerIndProgID, g_szProgID) ;}//// 在Windows注册表中注销组件//STDAPI DllUnregisterServer(){ return UnregisterServer(CLSID_Component1, g_szVerIndProgID, g_szProgID) ;}/////////////////////////////////////////////////////////////// DLL module information//将模块句柄保存在全局变量g_hModule中，以供DllRegisterServer和 //DllUnregisterServer使用BOOL APIENTRY DllMain(HANDLE hModule, DWord dwReason, void* lpReserved){ if (dwReason == DLL_PROCESS_ATTACH) { g_hModule = hModule ; } return TRUE ;}

Cmpnt.def，定义dll要输出的函数

LIBRARY Cmpnt.dllDESCRipTION 'Chapter 7 Example COM Component (c)1996-1997 Dale E. Rogerson'EXPORTS DllGetClassObject @2 PRIVATE DllCanUnloadNow @3 PRIVATE DllRegisterServer @4 PRIVATE DllUnregisterServer @5 PRIVATE

注册组件

#ifndef __Registry_H__#define __Registry_H__//// Registry.h// - Helper functions 登记、注销组件//// 在Windows注册表中登记组件// 被DllRegisterServer调用HRESULT RegisterServer(HMODULE hModule, const CLSID& clsid, const char* szFriendlyName, const char* szVerIndProgID, const char* szProgID) ;// 在Windows注册表中注销组件// 被DllUnregisterServer调用HRESULT UnregisterServer(const CLSID& clsid, const char* szVerIndProgID, const char* szProgID) ;#endif//// Registry.cpp////定义了 #define interface struct#include <objbase.h>#include <assert.h>#include "Registry.h"//////////////////////////////////////////////////////////// Internal helper functions prototypes//// Set the given key and its value.BOOL setKeyAndValue(const char* pszPath, const char* szSubkey, const char* szValue) ;// Convert a CLSID into a char string.void CLSIDtochar(const CLSID& clsid, char* szCLSID, int length) ;// Delete szKeyChild and all of its descendents.LONG recursiveDeleteKey(HKEY hKeyParent, const char* szKeyChild) ;//////////////////////////////////////////////////////////// Constants//// Size of a CLSID as a stringconst int CLSID_STRING_SIZE = 39 ;///////////////////////////////////////////////////////////// Public function implementation////// 在Windows注册表中登记组件//HRESULT RegisterServer(HMODULE hModule, // DLL module handle const CLSID& clsid, // Class ID const char* szFriendlyName, // Friendly Name const char* szVerIndProgID, // Programmatic const char* szProgID) // IDs{ // Get server location. char szModule[512] ; DWORD dwResult = ::GetModuleFileName(hModule, szModule, sizeof(szModule)/sizeof(char)) ; assert(dwResult != 0) ; // Convert the CLSID into a char. char szCLSID[CLSID_STRING_SIZE] ; CLSIDtochar(clsid, szCLSID, sizeof(szCLSID)) ; // Build the key CLSID//{...} char szKey[64] ; strcpy(szKey, "CLSID//") ; strcat(szKey, szCLSID) ; // Add the CLSID to the registry. setKeyAndValue(szKey, NULL, szFriendlyName) ; // Add the server filename subkey under the CLSID key. setKeyAndValue(szKey, "InprocServer32", szModule) ; // Add the ProgID subkey under the CLSID key. setKeyAndValue(szKey, "ProgID", szProgID) ; // Add the version-independent ProgID subkey under CLSID key. setKeyAndValue(szKey, "VersionIndependentProgID", szVerIndProgID) ; // Add the version-independent ProgID subkey under HKEY_CLASSES_ROOT. setKeyAndValue(szVerIndProgID, NULL, szFriendlyName) ; setKeyAndValue(szVerIndProgID, "CLSID", szCLSID) ; setKeyAndValue(szVerIndProgID, "CurVer", szProgID) ; // Add the versioned ProgID subkey under HKEY_CLASSES_ROOT. setKeyAndValue(szProgID, NULL, szFriendlyName) ; setKeyAndValue(szProgID, "CLSID", szCLSID) ; return S_OK ;}//// 在Windows注册表中注销组件//LONG UnregisterServer(const CLSID& clsid, // Class ID const char* szVerIndProgID, // Programmatic const char* szProgID) // IDs{ // Convert the CLSID into a char. char szCLSID[CLSID_STRING_SIZE] ; CLSIDtochar(clsid, szCLSID, sizeof(szCLSID)) ; // Build the key CLSID//{...} char szKey[64] ; strcpy(szKey, "CLSID//") ; strcat(szKey, szCLSID) ; // Delete the CLSID Key - CLSID/{...} LONG lResult = recursiveDeleteKey(HKEY_CLASSES_ROOT, szKey) ; assert((lResult == ERROR_SUCCESS) || (lResult == ERROR_FILE_NOT_FOUND)) ; // Subkey may not exist. // Delete the version-independent ProgID Key. lResult = recursiveDeleteKey(HKEY_CLASSES_ROOT, szVerIndProgID) ; assert((lResult == ERROR_SUCCESS) || (lResult == ERROR_FILE_NOT_FOUND)) ; // Subkey may not exist. // Delete the ProgID key. lResult = recursiveDeleteKey(HKEY_CLASSES_ROOT, szProgID) ; assert((lResult == ERROR_SUCCESS) || (lResult == ERROR_FILE_NOT_FOUND)) ; // Subkey may not exist. return S_OK ;}/////////////////////////////////////////////////////////////// Internal helper functions//// Convert a CLSID to a char string.void CLSIDtochar(const CLSID& clsid, char* szCLSID, int length){ assert(length >= CLSID_STRING_SIZE) ; // Get CLSID LPOLESTR wszCLSID = NULL ; HRESULT hr = StringFromCLSID(clsid, &wszCLSID) ; assert(SUCCEEDED(hr)) ; // Covert from wide characters to non-wide. wcstombs(szCLSID, wszCLSID, length) ; // Free memory. CoTaskMemFree(wszCLSID) ;}//// Delete a key and all of its descendents.//LONG recursiveDeleteKey(HKEY hKeyParent, // Parent of key to delete const char* lpszKeyChild) // Key to delete{ // Open the child. HKEY hKeyChild ; LONG lRes = RegOpenKeyEx(hKeyParent, lpszKeyChild, 0, KEY_ALL_access, &hKeyChild) ; if (lRes != ERROR_SUCCESS) { return lRes ; } // Enumerate all of the decendents of this child. FILETIME time ; char szBuffer[256] ; DWORD dwSize = 256 ; while (RegEnumKeyEx(hKeyChild, 0, szBuffer, &dwSize, NULL, NULL, NULL, &time) == S_OK) { // Delete the decendents of this child. lRes = recursiveDeleteKey(hKeyChild, szBuffer) ; if (lRes != ERROR_SUCCESS) { // Cleanup before exiting. RegCloseKey(hKeyChild) ; return lRes; } dwSize = 256 ; } // Close the child. RegCloseKey(hKeyChild) ; // Delete this child. return RegDeleteKey(hKeyParent, lpszKeyChild) ;}//// Create a key and set its value.// - This helper function was borrowed and modifed from// Kraig Brockschmidt's book Inside OLE.//BOOL setKeyAndValue(const char* szKey, const char* szSubkey, const char* szValue){ HKEY hKey; char szKeyBuf[1024] ; // Copy keyname into buffer. strcpy(szKeyBuf, szKey) ; // Add subkey name to buffer. if (szSubkey != NULL) { strcat(szKeyBuf, "//") ; strcat(szKeyBuf, szSubkey ) ; } // Create and open key and subkey. long lResult = RegCreateKeyEx(HKEY_CLASSES_ROOT , szKeyBuf, 0, NULL, REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, NULL, &hKey, NULL) ; if (lResult != ERROR_SUCCESS) { return FALSE ; } // Set the Value. if (szValue != NULL) { RegSetValueEx(hKey, NULL, 0, REG_SZ, (BYTE *)szValue, strlen(szValue)+1) ; } RegCloseKey(hKey) ; return TRUE ;}

在Cmpnt.dll的编译和连接后使用以下命令

regsvr32 -s Cmpnt.dll

REGSVR32.exe将调用DllRegisterServer函数完成组件的登记

参考 http://www.360doc.com/content/12/0228/09/7023119_190190971.shtml

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