原创 COM初探（五）——从IDispatch接口继承(转帖)

（一）目标
本文用一个简单的例子来讲述如何使我们的COM对象可以被脚本语言调用。

（二）IDL文件
为了在脚本语言环境中使用COM组件，COM规范规定要在脚本语言环境使用的COM必须实现IDispatch接口。
下面我们定义接口ITimeBeijing，请注意这个文件和我们以前的文件的不同点：

import "oaidl.idl";
import "ocidl.idl";

[
 uuid(30002489-29D8-4c48-9B1F-D6660A818E7B),
 object,
 dual,//这个标识说明定义的是双接口
 pointer_default(unique)
]
interface ITimeBeijing : IDispatch//必须从IDispatch接口派生
{
 [id(1)] HRESULT GetHour([out, retval] int * hour);//每个函数前都有id号，便于调用
 [id(2)] HRESULT GetMinute([out, retval] int * min);
 [id(3)] HRESULT GetSecond([out, retval] int * sec);
};

[
 uuid(8AE3C9BA-CEE9-4d33-A4C1-DB4FBFBB9A43),
 version(1.0),
]
library TimeBeijingLib
{
 importlib("stdole32.tlb");
 importlib("stdole2.tlb");

 [
  uuid(ECE8BF15-11FB-45a4-90A1-1788DDAB31AC),
 ]
 coclass TimeBeijingClass//com类
 {
  [default] interface ITimeBeijing;
 };
};

（三）建立COM类TimeBeijingClass
请注意和以前的不同点。
这里的类需要实现3个接口：IUnknown, IDispatch和ITimeBeijing。

// TimeBeijingClass.h: interface for the TimeBeijingClass class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(AFX_TIMEBEIJINGCLASS_H__E9800212_16E2_4BE3_B646_420DC02F50AE__INCLUDED_)
#define AFX_TIMEBEIJINGCLASS_H__E9800212_16E2_4BE3_B646_420DC02F50AE__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include "TimeBeijing.h"

class TimeBeijingClass : public ITimeBeijing 
{
public:
 TimeBeijingClass();
 ~TimeBeijingClass();

public:
 // IUnknown
 STDMETHOD(QueryInterface)(REFIID riid, void **ppv);
 STDMETHOD_(ULONG, AddRef)();
 STDMETHOD_(ULONG, Release)();

 // IDispatch
 STDMETHOD(GetTypeInfoCount)(UINT * pit);
 STDMETHOD(GetTypeInfo)(UINT it,LCID lcid,ITypeInfo **ppti);
 STDMETHOD(GetIDsOfNames)(REFIID riid,
  OLECHAR ** pNames,
  UINT nNames,
  LCID lcid,
  DISPID * pdispids);

 STDMETHOD(Invoke)(DISPID id,
  REFIID riid,
  LCID lcid,
  WORD wFlags,
  DISPPARAMS *pd,
  VARIANT * pVarResult,
  EXCEPINFO * pe,
  UINT *pu);

 // ITimeBeijing
 STDMETHOD(GetHour)(int * hour);
 STDMETHOD(GetMinute)(int * min);
 STDMETHOD(GetSecond)(int * sec);

private:
 LONG m_cRef;
};

#endif // !defined(AFX_TIMEBEIJINGCLASS_H__E9800212_16E2_4BE3_B646_420DC02F50AE__INCLUDED_)

// TimeBeijingClass.cpp: implementation of the TimeBeijingClass class.
//
//////////////////////////////////////////////////////////////////////

#include "TimeBeijingClass.h"
#include "stdio.h"
#include <time.h>
#include "TimeBeijing_i.c"
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

TimeBeijingClass::TimeBeijingClass()
{
 printf("TimeBeijingClass - Constructor\n");
 m_cRef = 0;
}

TimeBeijingClass::~TimeBeijingClass()
{
 printf("TimeBeijingClass - Destructor\n");
}

// IUnknown
STDMETHODIMP TimeBeijingClass::QueryInterface(REFIID riid, void **ppv)
{
 printf("TimeBeijingClass - QueryInterface\n");
 if(riid == IID_ITimeBeijing)
  *ppv = static_cast<ITimeBeijing *>(this);
 else if(riid == IID_IUnknown)
  *ppv = static_cast<ITimeBeijing *>(this);
 else if(riid == IID_IDispatch)
  *ppv = static_cast<IDispatch *>(this);
 else {
  *ppv = 0;
  return E_NOINTERFACE;
 }
 
 reinterpret_cast<IUnknown *>(*ppv)->AddRef();
 return S_OK;
}

STDMETHODIMP_(ULONG) TimeBeijingClass::AddRef()
{
 printf("TimeBeijingClass - AddRef\n");
 return ++m_cRef;
}

STDMETHODIMP_(ULONG) TimeBeijingClass::Release()
{
 printf("TimeBeijingClass - Release\n");
 ULONG res = --m_cRef; 
 if(res == 0)
  delete this;
 return res;
}

// IDispatch
//此函数是重点，请结合程序并参考msdn理解其中参数的含义
STDMETHODIMP TimeBeijingClass::Invoke(DISPID id, REFIID riid, LCID lcid,
           WORD wFlags, DISPPARAMS *pd,
           VARIANT * pVarResult, EXCEPINFO * pe, UINT *pu)
{
 if(riid == IID_ITimeBeijing)
    { 
  if(1 == id)
   return GetHour(&pVarResult->intVal);
  else if (2 == id)
   return GetMinute(&pVarResult->intVal);
  else if (3 == id)
   return GetSecond(&pVarResult->intVal);
  else
   return E_FAIL;
 }
 else
  return E_NOINTERFACE;

}

//为了简化程序，下面的接口函数都没有实现
STDMETHODIMP TimeBeijingClass::GetIDsOfNames(REFIID riid, OLECHAR ** pNames,
            UINT nNames, LCID lcid, DISPID * pdispids)
{
 return E_NOTIMPL;
}

STDMETHODIMP TimeBeijingClass::GetTypeInfo(UINT it,LCID lcid,ITypeInfo **ppti)
{
 return E_NOTIMPL;
}

STDMETHODIMP TimeBeijingClass::GetTypeInfoCount(UINT * pit)
{
 return E_NOTIMPL;
}

// ITimeBeijing
STDMETHODIMP TimeBeijingClass::GetHour(int * hour)
{
 printf("TimeBeijingClass - GetHour\n");
 
 time_t ltime;
 struct tm *today;
 
 time(&ltime);
 today = localtime(&ltime);
 
 *hour = today->tm_hour;
 
 return S_OK;
}

STDMETHODIMP TimeBeijingClass::GetMinute(int * min)
{
 printf("TimeBeijingClass - GetMinute\n");
 
 time_t ltime;
 struct tm *today;
 
 time(&ltime);
 today = localtime(&ltime);

 *min = today->tm_min;
 
 return S_OK;
}

STDMETHODIMP TimeBeijingClass::GetSecond(int * sec)
{
 printf("TimeBeijingClass - GetMinute\n");
 
 time_t ltime;
 struct tm *today;
 
 time(&ltime);
 today = localtime(&ltime);
 
 *sec = today->tm_sec;
 
 return S_OK;
}

（四）类工厂文件（微小的变化：QueryInterface）
// TimeBeijingClassFactory.h: interface for the TimeBeijingClassFactory class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(AFX_TIMEBEIJINGCLASSFACTORY_H__AB2637DD_45D2_48CD_BAD8_46E372268A8C__INCLUDED_)
#define AFX_TIMEBEIJINGCLASSFACTORY_H__AB2637DD_45D2_48CD_BAD8_46E372268A8C__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include <unknwn.h>

class TimeBeijingClassFactory : public IClassFactory 
{
public:
 TimeBeijingClassFactory();
 ~TimeBeijingClassFactory();

public:
 //IUnknow Method
 STDMETHODIMP QueryInterface(REFIID,void**);
 STDMETHODIMP_(ULONG) AddRef();
 STDMETHODIMP_(ULONG) Release();
 
 //IClassFactory Method
 STDMETHODIMP CreateInstance(IUnknown * ,REFIID ,void **);
 STDMETHODIMP LockServer(BOOL fLock);
 
private:
 LONG m_cRef;

};

#endif // !defined(AFX_TIMEBEIJINGCLASSFACTORY_H__AB2637DD_45D2_48CD_BAD8_46E372268A8C__INCLUDED_)

// TimeBeijingClassFactory.cpp: implementation of the TimeBeijingClassFactory class.
//
//////////////////////////////////////////////////////////////////////

#include "TimeBeijingClassFactory.h"
#include "stdio.h"
#include "TimeBeijingClass.h"
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

extern LONG g_cObjectAndLocks;

TimeBeijingClassFactory::TimeBeijingClassFactory()
{
 printf("TimeBeijingClassFactory - constructor\n");
 m_cRef = 0;
}

TimeBeijingClassFactory::~TimeBeijingClassFactory()
{
 printf("TimeBeijingClassFactory - destructor\n");
}

STDMETHODIMP_(ULONG) TimeBeijingClassFactory::AddRef(void)
{
 printf("TimeBeijingClassFactory - AddRef\n");
 return InterlockedIncrement(&m_cRef);
}

STDMETHODIMP_(ULONG) TimeBeijingClassFactory::Release(void)
{
 printf("TimeBeijingClassFactory - Release\n");
 return ::InterlockedDecrement(&m_cRef);
}

STDMETHODIMP TimeBeijingClassFactory::QueryInterface(REFIID riid,void ** ppv)
{
 printf("TimeBeijingClassFactory - QueryInterface\n");

 *ppv = NULL;
 if(riid == IID_IUnknown || riid == IID_IClassFactory || riid == IID_IDispatch)//变化在此！！！
 {
  *ppv = static_cast<IClassFactory *>(this);
  reinterpret_cast<IUnknown*>(*ppv)->AddRef();
  return S_OK;
 }
 else
  return (*ppv=0),E_NOINTERFACE;
}

STDMETHODIMP TimeBeijingClassFactory::CreateInstance(IUnknown * pUnkOuter,REFIID riid,void ** ppv)
{
 printf("TimeBeijingClassFactory - CreateInstance\n");

 *ppv=NULL;
 
 if(pUnkOuter != NULL)
  return CLASS_E_NOAGGREGATION;
 
 TimeBeijingClass * pTimeBeijingClass = new TimeBeijingClass;
 if(pTimeBeijingClass == NULL)
  return E_OUTOFMEMORY;
 
 HRESULT hr = pTimeBeijingClass->QueryInterface(riid,ppv);
 
 if(FAILED(hr))
  delete pTimeBeijingClass;
 
 return hr;
 
}

STDMETHODIMP TimeBeijingClassFactory::LockServer(BOOL fLock)
{
 printf("TimeBeijingClassFactory - LockServer\n");
 if(fLock)
  ::InterlockedIncrement(&g_cObjectAndLocks);
 else
  ::InterlockedDecrement(&g_cObjectAndLocks);
 return NOERROR;
 
}

（五）服务器主文件Server.cpp（没有变化）
#include <objbase.h>
#include <initguid.h>
#include "TimeBeijing.h"
#include "TimeBeijing_i.c"
#include "TimeBeijingClassFactory.h"

HINSTANCE  g_hinstDll;//DLL实例句柄

LONG g_cObjectAndLocks;

const char * g_RegTable[][3]={//COM对象注册
 {"CLSID\\{ECE8BF15-11FB-45a4-90A1-1788DDAB31AC}",
  0,
  "TimeBeijing"},

 {"CLSID\\{ECE8BF15-11FB-45a4-90A1-1788DDAB31AC}\\InprocServer32",
 0,
 (const char * )-1},
 
 {"CLSID\\{ECE8BF15-11FB-45a4-90A1-1788DDAB31AC}\\ProgID",0,"Justin.TimeBeijing.3"},
 {"Justin.TimeBeijing.3",0,"TimeBeijing"},
 {"Justin.TimeBeijing.3\\CLSID",0,"{ECE8BF15-11FB-45a4-90A1-1788DDAB31AC}"},
};

//DLL入口
BOOL APIENTRY DllMain( HANDLE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
      )
{
 g_hinstDll = (HINSTANCE) hModule;//保存句柄

    return TRUE;
}

STDAPI DllUnregisterServer(void)//从注册表中注销
{
 HRESULT hr = S_OK;
 char szFileName [MAX_PATH];
 ::GetModuleFileName(g_hinstDll,szFileName,MAX_PATH);

 int nEntries = sizeof(g_RegTable) / sizeof(*g_RegTable);

 for(int i = 0; SUCCEEDED(hr) && i < nEntries; i ++)
 {
  const char * pszKeyName = g_RegTable[0];
  long err = ::RegDeleteKey(HKEY_CLASSES_ROOT, pszKeyName);
  if( err != ERROR_SUCCESS)
   hr = S_FALSE;
 }