COM初探（五）——从IDispatch接口继承

（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[i][0];
  long err = ::RegDeleteKey(HKEY_CLASSES_ROOT, pszKeyName);
  if( err != ERROR_SUCCESS)
   hr = S_FALSE;
}

return hr;
}

STDAPI DllRegisterServer(void)//注册服务器
{
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[i][0];
  const char * pszValueName = g_RegTable[i][1];
  const char * pszValue = g_RegTable[i][2];

  if(pszValue == (const char *) - 1)
  {
   pszValue = szFileName;
  }

  HKEY hkey;
  long err = ::RegCreateKey(HKEY_CLASSES_ROOT, pszKeyName, &hkey);
  if(err == ERROR_SUCCESS)
  {
   err = ::RegSetValueEx( hkey,
     pszValueName,
     0,
     REG_SZ,
     ( const BYTE*)pszValue,
     ( strlen(pszValue)+1 ) );
   ::RegCloseKey(hkey);
  }
  if( err != ERROR_SUCCESS)
  {
   ::DllUnregisterServer();
   hr = E_FAIL;
  }

}
   return hr;
}

STDAPI DllGetClassObject(REFCLSID rclsid ,REFIID riid,void **ppv)
{
if(rclsid == CLSID_TimeBeijingClass)
{
  TimeBeijingClassFactory *pFactory = new TimeBeijingClassFactory;

  if(pFactory == NULL)
   return E_OUTOFMEMORY;

  HRESULT hr = pFactory->QueryInterface(riid, ppv);
  return hr;
}

return CLASS_E_CLASSNOTAVAILABLE;
}

STDAPI DllCanUnloadNow(void)
{
return ( g_cObjectAndLocks == 0 )
? S_OK : E_FAIL;
}

（六）DEF文件（没有变化）
LIBRARY "TimeBeijing.DLL"
EXPORTS
DllCanUnloadNow     @1 PRIVATE
DllGetClassObject   @2 PRIVATE
DllRegisterServer   @3 PRIVATE
DllUnregisterServer @4 PRIVATE

编译链接上述文件，得到了服务器端程序。
让我们启动服务器：regsvr32 TimeBeijing.DLL （回车）

（七）vc客户端
下面进入测试阶段，首先，我们建立vc客户端进行测试。

// TEST.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include "TEST.h"
#include "../TimeBeijing_i.c"
#include "atlbase.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// The one and only application object

CWinApp theApp;

using namespace std;

int _tmain(int argc, TCHAR* argv[], TCHAR* envp[])
{
cout << "Initialize COM Runtime......";
HRESULT hr = ::CoInitialize(NULL);
if(SUCCEEDED(hr))
  cout << "ok" << endl;
else
{
  cout << "failed" << endl;
  CoUninitialize();
  system("pause");
  exit(1);
}

IDispatch *pDispatch = NULL;//IDispatch 接口指针

cout << "Get IDispatch Interface Pointer......";
hr = ::CoCreateInstance(CLSID_TimeBeijingClass,
  NULL,
  CLSCTX_INPROC,
  IID_IDispatch,
  (void**)&pDispatch);

if(SUCCEEDED(hr))
  cout << "ok" << endl;
else
{
  cout << "failed" << endl;
  CoUninitialize();
  system("pause");
  exit(1);
}

cout << "Now use IDispatch Interface..." << endl;

CComVariant varResult1;
CComVariant varResult2;
CComVariant varResult3;
varResult1.Clear();
varResult2.Clear();
varResult3.Clear();

cout << "Use Method ID.1......";
hr = pDispatch->Invoke(0x1, // ID 1
  IID_ITimeBeijing,
  LOCALE_USER_DEFAULT,
  DISPATCH_METHOD,
  NULL,
  &varResult1,
  NULL,
  NULL);

if(SUCCEEDED(hr))
  cout << "ok" << endl;
else
{
  cout << "failed" << endl;
  pDispatch->Release();
  CoUninitialize();
  system("pause");
  exit(1);
}

cout << "Use Method ID.2......";
hr = pDispatch->Invoke(0x2, // ID 2
  IID_ITimeBeijing,
  LOCALE_USER_DEFAULT,
  DISPATCH_METHOD,
  NULL,
  &varResult2,
  NULL,
  NULL);

if(SUCCEEDED(hr))
  cout << "ok" << endl;
else
{
  cout << "failed" << endl;
  pDispatch->Release();
  CoUninitialize();
  system("pause");
  exit(1);
}

cout << "Use Method ID.3......";
hr = pDispatch->Invoke(0x3, // ID 1
  IID_ITimeBeijing,
  LOCALE_USER_DEFAULT,
  DISPATCH_METHOD,
  NULL,
  &varResult3,
  NULL,
  NULL);

if(SUCCEEDED(hr))
  cout << "ok" << endl;
else
{
  cout << "failed" << endl;
  pDispatch->Release();
  CoUninitialize();
  system("pause");
  exit(1);
}

printf("Time NOW : %d - %d - %d /n", varResult1.intVal,
varResult2.intVal, varResult3.intVal);

cout << "Close COM Runtime......" <<endl;
pDispatch->Release();
::CoUninitialize();

system("pause");
return 0;
}

测试结果：
Initialize COM Runtime......ok
Get IDispatch Interface Pointer......TimeBeijingClassFactory - constructor
TimeBeijingClassFactory - QueryInterface
TimeBeijingClassFactory - AddRef
TimeBeijingClassFactory - CreateInstance
TimeBeijingClass - Constructor
TimeBeijingClass - QueryInterface
TimeBeijingClass - AddRef
TimeBeijingClass - AddRef
TimeBeijingClass - Release
TimeBeijingClassFactory - Release
TimeBeijingClass - QueryInterface
TimeBeijingClass - AddRef
TimeBeijingClass - Release
ok
Now use IDispatch Interface...
Use Method ID.1......TimeBeijingClass - GetHour
ok
Use Method ID.2......TimeBeijingClass - GetMinute
ok
Use Method ID.3......TimeBeijingClass - GetMinute
ok
Time NOW : 14 - 37 - 50
Close COM Runtime......
TimeBeijingClass - Release
TimeBeijingClass - Destructor
请按任意键继续 . . .

（八）vb客户端
建立带有一个按钮的Standard EXE工程。
注意选中Project --> References -->TimeBeijingLib
输入下列代码：

Private Sub Command1_Click()
    Dim c As TimeBeijingClass
    Dim h As Integer
    Dim m As Integer
    Dim s As Integer

    Set c = New TimeBeijingClass

    h = c.GetHour
    m = c.GetMinute
    s = c.GetSecond

    Print "Time NOW: "; h; " - "; m; " - "; s
End Sub

显示结果如下：
Time NOW: 20 - 6 - 34

秒客网

COM初探（五）——从IDispatch接口继承

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