COM初探（四）——本地EXE COM服务器

（一）目标

讲述如何建立本地（Local，EXE）COM服务器的例子似乎不多，为此，本文专门讲述如何用vc手工建立本地EXE COM服务器程序。本文假设读者对COM有一定的基础。

（二）准备

1）使用vc6建立Win32 Application工程，选择a simple application。

2）从stdafx.h中删除：#define WIN32_LEAN_AND_MEAN

（三）建立IDL文件

此文件中定义了接口ITimeBeijing和COM类TimeBeijingClass

import "oaidl.idl";

[

object,

uuid(61A1C81D-82CA-44e4-A60E-7BDD8E58A833),

oleautomation

]

interface ITimeBeijing : IUnknown//定义ITimeBeijing接口

{

HRESULT GetTimeBeijing([out]int * hour, [out]int * min, [out]int * sec);

};

[

uuid(1E850106-D5C5-4249-86DF-40256DB3A5D2),

version(1.0)

]

library TimeBeijingLib

{

importlib("stdole32.tlb");

[

uuid(57E9BE40-AE4F-493b-A79B-FBBF7EC7F2AE)

]

coclass TimeBeijingClass//定义TimeBeijingClass类

{

[default] interface ITimeBeijing;

};

（四）添加COM类TimeBeijingClass

TimeBeijingClass在由上面idl文件编译生成的文件中已经前置声明了。这里我们实现了它的功能（获取当前北京时间）

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

//////////////////////////////////////////////////////////////////////

#if !defined(AFX_TIMEBEIJINGCLASS_H__E9D2F0AF_8EBB_438B_A2BC_6206DDAB91B6__INCLUDED_)

#define AFX_TIMEBEIJINGCLASS_H__E9D2F0AF_8EBB_438B_A2BC_6206DDAB91B6__INCLUDED_

#if _MSC_VER > 1000

#pragma once

#endif // _MSC_VER > 1000

#include "TimeBeijing.h"

class TimeBeijingClass : public ITimeBeijing

{

public:

TimeBeijingClass();

~TimeBeijingClass();

private:

ULONG m_cRef;

public:

//IUnknown 方法

STDMETHOD(QueryInterface)(REFIID riid, void **ppv);

STDMETHOD_(ULONG, AddRef)();

STDMETHOD_(ULONG, Release)();

//ITimeBeijing 方法

STDMETHOD(GetTimeBeijing)(int * hour, int* min, int * sec);

};

#endif // !defined(AFX_TIMEBEIJINGCLASS_H__E9D2F0AF_8EBB_438B_A2BC_6206DDAB91B6__INCLUDED_)

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

//////////////////////////////////////////////////////////////////////

#include "StdAfx.h"

#include "TimeBeijingClass.h"

#include "time.h"

#include "stdio.h"

#include "TimeBeijing_i.c"

//////////////////////////////////////////////////////////////////////

// Construction/Destruction

//////////////////////////////////////////////////////////////////////

TimeBeijingClass::TimeBeijingClass()

{

printf("TimeBeijingClass - constructor\n");

m_cRef = 0;

}

TimeBeijingClass::~TimeBeijingClass()

{

printf("TimeBeijingClass - destructor\n");

}

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 {

*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;

}

STDMETHODIMP TimeBeijingClass::GetTimeBeijing(int * hour, int* min, int * sec)

{

printf("TimeBeijingClass - GetTimeBeijing\n");

time_t ltime;

struct tm *today;

time(&ltime);

today = localtime(&ltime);

*hour = today->tm_hour;

*min = today->tm_min;

*sec = today->tm_sec;

return S_OK;

}

（五）添加工厂类TimeBeijingClassFactory

类工厂可以生成类的实例。在标准的COM实现中，我们都是通过使用类工厂来得到目的接口指针的。

类工厂从IClassFactory接口派生，有两个接口函数：CreateInstance和LockServer。

CreateInstance用于建立目标COM类的实例并返回相应接口。

LockServer用于全局的引用计数。当计数为0时，服务器自动关闭。

// 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 方法

STDMETHODIMP QueryInterface(REFIID,void**);

STDMETHODIMP_(ULONG) AddRef();

STDMETHODIMP_(ULONG) Release();

//IClassFactory 方法

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 "StdAfx.h"

#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)

{

*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

{

if(0 == ::InterlockedDecrement(&g_cObjectAndLocks))

PostQuitMessage(0);

}

return NOERROR;

}

（六）服务器端主文件

客户端主文件负责注册工厂类，使得外部程序可以访问本地的COM类。

#include "stdafx.h"

#include "TimeBeijing_i.c"

#include "TimeBeijingClassFactory.h"

LONG g_cObjectAndLocks;//用于全局的应用计数

int APIENTRY WinMain(HINSTANCE hInstance,//程序的入口点

HINSTANCE hPrevInstance,

LPSTR lpCmdLine,

int nCmdShow)

{

HRESULT hr;

CoInitialize(NULL); //初始化COM环境

//读入并注册类型库

ITypeLib* pTLib = NULL;

hr = LoadTypeLibEx(L"TimeBeijing.tlb", REGKIND_REGISTER, &pTLib);

pTLib->Release();

if ( FAILED(hr) )

{

MessageBox(NULL, "LoadTypeLibEx() failed", "", MB_OK);

exit(1);

}

// 判断是否被SCM调用

if(strstr(lpCmdLine, "/Embedding") || strstr(lpCmdLine, "-Embedding"))

{

MessageBox(NULL, "TimeBeijing Server is registering the classes",

"EXE Message!", MB_OK | MB_SETFOREGROUND);

// 工厂类

TimeBeijingClassFactory ClassFactory;

// 注册工厂类

DWORD regID = 0;

hr = CoRegisterClassObject(CLSID_TimeBeijingClass,

(IClassFactory*)&ClassFactory,

CLSCTX_LOCAL_SERVER,

REGCLS_MULTIPLEUSE,

&regID);

if ( FAILED(hr) )

{

MessageBox(NULL, "CoRegisterClassObject()", "", MB_OK);

CoUninitialize();

exit(1);

}

// 进入消息循环，直到WM_QUIT到达

MSG ms;

while(GetMessage(&ms, 0, 0, 0))

{

TranslateMessage(&ms);

DispatchMessage(&ms);

}

// 注销工厂类

CoRevokeClassObject(regID);

}

// 退出COM环境

CoUninitialize();

MessageBox(NULL, "Server is dying",

"EXE Message!", MB_OK | MB_SETFOREGROUND);

return 0;

}

（七）建立注册文件

注册文件用于添加程序注册表信息，文件内容如下：

REGEDIT

HKEY_CLASSES_ROOT\Justin.TimeBeijingServer.TimeBeijingClass\CLSID = {57E9BE40-AE4F-493b-A79B-FBBF7EC7F2AE}

HKEY_CLASSES_ROOT\CLSID\{57E9BE40-AE4F-493b-A79B-FBBF7EC7F2AE} = Justin.TimeBeijingServer.TimeBeijingClass

HKEY_CLASSES_ROOT\CLSID\{57E9BE40-AE4F-493b-A79B-FBBF7EC7F2AE}\LocalServer32 = D:\COM\Debug\COM.exe

双击此文件，将注册信息加入注册表。

（八）建立客户端

上面的程序编译链接后就可以得到一个本地EXE COM服务器。下面为了测试，我们将建立一个客户程序。

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

#include "stdafx.h"

#include "TEST.h"

#include "../TimeBeijing.h"

#include "../TimeBeijing_i.c"

#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 << "初始化COM环境" << endl;

CoInitialize(NULL);

HRESULT hr;

IClassFactory* pICF = NULL;//定义接口指针

ITimeBeijing *pTimeBeijing = NULL;

cout << "获取工厂接口指针" << endl;

hr = CoGetClassObject(CLSID_TimeBeijingClass,

CLSCTX_LOCAL_SERVER,

NULL,

IID_IClassFactory,

(void**)&pICF);

if ( FAILED(hr) )

{

MessageBox(NULL, "CoGetClassObject()", "fail", MB_OK);

exit(1);

}

cout << "获取ITimeBeijing接口指针" << endl;

hr = pICF->CreateInstance(NULL,

IID_ITimeBeijing,

(void**)&pTimeBeijing);

if ( FAILED(hr) )

{

MessageBox(NULL, "CoCreateInstance()", "fail", MB_OK);

exit(1);

}

int h, m, s;

pTimeBeijing->GetTimeBeijing(&h, &m, &s);//使用接口

printf("Time NOW : %d : %d : %d\n", h, m, s);//显示结果

if ( pICF ) pICF->Release();//释放接口

if ( pTimeBeijing ) pTimeBeijing->Release();

cout << "退出COM环境" << endl;

CoUninitialize();

cout << "END" << endl;

getchar();

return 0;

}

（九）测试结果

初始化COM环境

获取工厂接口指针

获取ITimeBeijing接口指针

Time NOW : 12 : 54 : 23

退出COM环境

END