深入解析C++程序中激发事件和COM中的事件处理
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本机 C++ 中的事件处理
// evh_native.cpp
#include <stdio.h>
[event_source(native)]
class CSource {
public:
__event void MyEvent(int nValue);
};
[event_receiver(native)]
class CReceiver {
public:
void MyHandler1(int nValue) {
printf_s("MyHandler1 was called with value %d.n",nValue);
}
void MyHandler2(int nValue) {
printf_s("MyHandler2 was called with value %d.n",nValue);
}
void hookEvent(CSource* pSource) {
__hook(&CSource::MyEvent,pSource,&CReceiver::MyHandler1);
__hook(&CSource::MyEvent,&CReceiver::MyHandler2);
}
void unhookEvent(CSource* pSource) {
__unhook(&CSource::MyEvent,&CReceiver::MyHandler1);
__unhook(&CSource::MyEvent,&CReceiver::MyHandler2);
}
};
int main() {
CSource source;
CReceiver receiver;
receiver.hookEvent(&source);
__raise source.MyEvent(123);
receiver.unhookEvent(&source);
}
输出： MyHandler2 was called with value 123. MyHandler1 was called with value 123. COM 中的事件处理
// evh_server.h
#pragma once
[ dual,uuid("00000000-0000-0000-0000-000000000001") ]
__interface IEvents {
[id(1)] HRESULT MyEvent([in] int value);
};
[ dual,uuid("00000000-0000-0000-0000-000000000002") ]
__interface IEventSource {
[id(1)] HRESULT FireEvent();
};
class DECLSPEC_UUID("530DF3AD-6936-3214-A83B-27B63C7997C4") CSource;
接着是服务器：
// evh_server.cpp
// compile with: /LD
// post-build command: Regsvr32.exe /s evh_server.dll
#define _ATL_ATTRIBUTES 1
#include <atlbase.h>
#include <atlcom.h>
#include "evh_server.h"
[ module(dll,name="EventSource",uuid="6E46B59E-89C3-4c15-A6D8-B8A1CEC98830") ];
[coclass,event_source(com),uuid("530DF3AD-6936-3214-A83B-27B63C7997C4")]
class CSource : public IEventSource {
public:
__event __interface IEvents;
HRESULT FireEvent() {
__raise MyEvent(123);
return S_OK;
}
};
再然后是客户端：
// evh_client.cpp
// compile with: /link /OPT:NOREF
#define _ATL_ATTRIBUTES 1
#include <atlbase.h>
#include <atlcom.h>
#include <stdio.h>
#include "evh_server.h"
[ module(name="EventReceiver") ];
[ event_receiver(com) ]
class CReceiver {
public:
HRESULT MyHandler1(int nValue) {
printf_s("MyHandler1 was called with value %d.n",nValue);
return S_OK;
}
HRESULT MyHandler2(int nValue) {
printf_s("MyHandler2 was called with value %d.n",nValue);
return S_OK;
}
void HookEvent(IEventSource* pSource) {
__hook(&IEvents::MyEvent,&CReceiver::MyHandler1);
__hook(&IEvents::MyEvent,&CReceiver::MyHandler2);
}
void UnhookEvent(IEventSource* pSource) {
__unhook(&IEvents::MyEvent,&CReceiver::MyHandler1);
__unhook(&IEvents::MyEvent,&CReceiver::MyHandler2);
}
};
int main() {
// Create COM object
CoInitialize(NULL);
{
IEventSource* pSource = 0;
HRESULT hr = CoCreateInstance(__uuidof(CSource),NULL,CLSCTX_ALL,__uuidof(IEventSource),(void **) &pSource);
if (FAILED(hr)) {
return -1;
}
// Create receiver and fire event
CReceiver receiver;
receiver.HookEvent(pSource);
pSource->FireEvent();
receiver.UnhookEvent(pSource);
}
CoUninitialize();
return 0;
}
输出 MyHandler1 was called with value 123. MyHandler2 was called with value 123. 依赖于布局的 COM 事件 [id(1)] HRESULT MyEvent1([in] int value); [id(2)] HRESULT MyEvent2([in] int value); 假定事件源具有以下形式：
[coclass,event_source(com)]
class CSource : public IEventSource {
public:
__event __interface IEvents;
HRESULT FireEvent() {
MyEvent1(123);
MyEvent2(123);
return S_OK;
}
};
则在事件接收器中，挂钩到 IEventSource 中的方法的任何处理程序必须与其名称和签名匹配，如下所示：
[coclass,event_receiver(com,true)]
class CReceiver {
public:
HRESULT MyEvent1(int nValue) { // name and signature matches MyEvent1
...
}
HRESULT MyEvent2(E c,char* pc) { // signature doesn't match MyEvent2
...
}
HRESULT MyHandler1(int nValue) { // name doesn't match MyEvent1 (or 2)
...
}
void HookEvent(IEventSource* pSource) {
__hook(IFace,pSource); // Hooks up all name-matched events
// under layout_dependent = true
__hook(&IFace::MyEvent1,&CReceive::MyEvent1); // valid
__hook(&IFace::MyEvent2,&CSink::MyEvent2); // not valid
__hook(&IFace::MyEvent1,&CSink:: MyHandler1); // not valid
}
};
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