我们知道实现C++和Javascript通讯有下表5种接口:
引擎 | 编写语言 | API接口 | C、C++与JavaScript交互(变量、函数、类) | vc2005编译静态库的大小 | 示例EXE的大小 | 执行、解析JavaScript的速度 |
Google V8 | C++ | C++ | 可以 | 23.1M | 1.1M | 最快 |
Firefox3.5以前 SpiderMonkey | C | C | 可以 | 1.3M | 500K | 慢 |
Firefox高版本SpiderMonkey | C++ | C | 可以 | 15.3M | 1.7M | 一般 |
Webkit JavaScriptCore | C++ | C | 可以 | 26.2M | 1.4M | 一般 |
IE | 未知 | COM | 可以 | 未知 | 100K(没有链接库) | 一般 |
IE的Trident引擎是非开源的,微软JavaScript引擎也是非开源的。微软对外提供了一组COM接口。使用这组COM接口,能够将微软的JavaScript、VBScript嵌入到C、C++、VB、C#等宿主语言中。
说到底其实也没什么好说的,先定义一个 CComPtr<IDispatch> 对象,然后调用其对象的Invoke函数,只要弄清楚他的参数正确的传递就好了。
除此之外该接口还提供有一种简易的方法。
CComPtr<IDispatch> Obj;
CComVariant var(true);
if( FAILED(Obj.Invoke1(L"ReflowDocument", &var)) )
MessageBox(_T("Invoke ReflowDocument failed."));
另外还有Invoke0、Invoke2、InvokeN、GetProperty、PutProperty、GetIDOfName、GetPropertyByName。这些函数的实现都在\VC\atlmfc\include\atlcomcli.h头文件中有声明和实现。
//specialization for IDispatch
template <>
class CComPtr<IDispatch> :
public CComPtrBase<IDispatch>
{
public:
CComPtr() throw()
{
}
CComPtr(_Inout_opt_ IDispatch* lp) throw() :
CComPtrBase<IDispatch>(lp)
{
}
CComPtr(_Inout_ const CComPtr<IDispatch>& lp) throw() :
CComPtrBase<IDispatch>(lp.p)
{
}
IDispatch* operator=(_Inout_opt_ IDispatch* lp) throw()
{
if(*this!=lp)
{
return static_cast<IDispatch*>(AtlComPtrAssign((IUnknown**)&p, lp));
}
return *this;
}
IDispatch* operator=(_Inout_ const CComPtr<IDispatch>& lp) throw()
{
if(*this!=lp)
{
return static_cast<IDispatch*>(AtlComPtrAssign((IUnknown**)&p, lp.p));
}
return *this;
}
CComPtr(_Inout_ CComPtr<IDispatch>&& lp) throw() :
CComPtrBase<IDispatch>()
{
p = lp.p;
lp.p = NULL;
}
IDispatch* operator=(_Inout_ CComPtr<IDispatch>&& lp) throw()
{
if (*this != lp)
{
if (p != NULL)
p->Release(); p = lp.p;
lp.p = NULL;
}
return *this;
}
// IDispatch specific stuff
_Check_return_ HRESULT GetPropertyByName(
_In_z_ LPCOLESTR lpsz,
_Out_ VARIANT* pVar) throw()
{
ATLASSERT(p);
ATLASSERT(pVar);
DISPID dwDispID;
HRESULT hr = GetIDOfName(lpsz, &dwDispID);
if (SUCCEEDED(hr))
hr = GetProperty(dwDispID, pVar);
return hr;
}
_Check_return_ HRESULT GetProperty(
_In_ DISPID dwDispID,
_Out_ VARIANT* pVar) throw()
{
return GetProperty(p, dwDispID, pVar);
}
_Check_return_ HRESULT PutPropertyByName(
_In_z_ LPCOLESTR lpsz,
_In_ VARIANT* pVar) throw()
{
ATLASSERT(p);
ATLASSERT(pVar);
DISPID dwDispID;
HRESULT hr = GetIDOfName(lpsz, &dwDispID);
if (SUCCEEDED(hr))
hr = PutProperty(dwDispID, pVar);
return hr;
}
_Check_return_ HRESULT PutProperty(
_In_ DISPID dwDispID,
_In_ VARIANT* pVar) throw()
{
return PutProperty(p, dwDispID, pVar);
}
_Check_return_ HRESULT GetIDOfName(
_In_z_ LPCOLESTR lpsz,
_Out_ DISPID* pdispid) throw()
{
return p->GetIDsOfNames(IID_NULL, const_cast<LPOLESTR*>(&lpsz), , LOCALE_USER_DEFAULT, pdispid);
}
// Invoke a method by DISPID with no parameters
_Check_return_ HRESULT Invoke0(
_In_ DISPID dispid,
_Out_opt_ VARIANT* pvarRet = NULL) throw()
{
DISPPARAMS dispparams = { NULL, NULL, , };
return p->Invoke(dispid, IID_NULL, LOCALE_USER_DEFAULT, DISPATCH_METHOD, &dispparams, pvarRet, NULL, NULL);
}
// Invoke a method by name with no parameters
_Check_return_ HRESULT Invoke0(
_In_z_ LPCOLESTR lpszName,
_Out_opt_ VARIANT* pvarRet = NULL) throw()
{
HRESULT hr;
DISPID dispid;
hr = GetIDOfName(lpszName, &dispid);
if (SUCCEEDED(hr))
hr = Invoke0(dispid, pvarRet);
return hr;
}
// Invoke a method by DISPID with a single parameter
_Check_return_ HRESULT Invoke1(
_In_ DISPID dispid,
_In_ VARIANT* pvarParam1,
_Out_opt_ VARIANT* pvarRet = NULL) throw()
{
DISPPARAMS dispparams = { pvarParam1, NULL, , };
return p->Invoke(dispid, IID_NULL, LOCALE_USER_DEFAULT, DISPATCH_METHOD, &dispparams, pvarRet, NULL, NULL);
}
// Invoke a method by name with a single parameter
_Check_return_ HRESULT Invoke1(
_In_z_ LPCOLESTR lpszName,
_In_ VARIANT* pvarParam1,
_Out_opt_ VARIANT* pvarRet = NULL) throw()
{
DISPID dispid;
HRESULT hr = GetIDOfName(lpszName, &dispid);
if (SUCCEEDED(hr))
hr = Invoke1(dispid, pvarParam1, pvarRet);
return hr;
}
// Invoke a method by DISPID with two parameters
_Check_return_ HRESULT Invoke2(
_In_ DISPID dispid,
_In_ VARIANT* pvarParam1,
_In_ VARIANT* pvarParam2,
_Out_opt_ VARIANT* pvarRet = NULL) throw();
// Invoke a method by name with two parameters
_Check_return_ HRESULT Invoke2(
_In_z_ LPCOLESTR lpszName,
_In_ VARIANT* pvarParam1,
_In_ VARIANT* pvarParam2,
_Out_opt_ VARIANT* pvarRet = NULL) throw()
{
DISPID dispid;
HRESULT hr = GetIDOfName(lpszName, &dispid);
if (SUCCEEDED(hr))
hr = Invoke2(dispid, pvarParam1, pvarParam2, pvarRet);
return hr;
}
// Invoke a method by DISPID with N parameters
_Check_return_ HRESULT InvokeN(
_In_ DISPID dispid,
_In_ VARIANT* pvarParams,
_In_ int nParams,
_Out_opt_ VARIANT* pvarRet = NULL) throw()
{
DISPPARAMS dispparams = { pvarParams, NULL, nParams, };
return p->Invoke(dispid, IID_NULL, LOCALE_USER_DEFAULT, DISPATCH_METHOD, &dispparams, pvarRet, NULL, NULL);
}
// Invoke a method by name with Nparameters
_Check_return_ HRESULT InvokeN(
_In_z_ LPCOLESTR lpszName,
_In_ VARIANT* pvarParams,
_In_ int nParams,
_Out_opt_ VARIANT* pvarRet = NULL) throw()
{
HRESULT hr;
DISPID dispid;
hr = GetIDOfName(lpszName, &dispid);
if (SUCCEEDED(hr))
hr = InvokeN(dispid, pvarParams, nParams, pvarRet);
return hr;
}
_Check_return_ static HRESULT PutProperty(
_In_ IDispatch* p,
_In_ DISPID dwDispID,
_In_ VARIANT* pVar) throw()
{
ATLASSERT(p);
ATLASSERT(pVar != NULL);
if (pVar == NULL)
return E_POINTER; if(p == NULL)
return E_INVALIDARG; ATLTRACE(atlTraceCOM, , _T("CPropertyHelper::PutProperty\n"));
DISPPARAMS dispparams = {NULL, NULL, , };
dispparams.rgvarg = pVar;
DISPID dispidPut = DISPID_PROPERTYPUT;
dispparams.rgdispidNamedArgs = &dispidPut; if (pVar->vt == VT_UNKNOWN || pVar->vt == VT_DISPATCH ||
(pVar->vt & VT_ARRAY) || (pVar->vt & VT_BYREF))
{
HRESULT hr = p->Invoke(dwDispID, IID_NULL,
LOCALE_USER_DEFAULT, DISPATCH_PROPERTYPUTREF,
&dispparams, NULL, NULL, NULL);
if (SUCCEEDED(hr))
return hr;
}
return p->Invoke(dwDispID, IID_NULL,
LOCALE_USER_DEFAULT, DISPATCH_PROPERTYPUT,
&dispparams, NULL, NULL, NULL);
}
_Check_return_ static HRESULT GetProperty(
_In_ IDispatch* p,
_In_ DISPID dwDispID,
_Out_ VARIANT* pVar) throw()
{
ATLASSERT(p);
ATLASSERT(pVar != NULL);
if (pVar == NULL)
return E_POINTER; if(p == NULL)
return E_INVALIDARG; ATLTRACE(atlTraceCOM, , _T("CPropertyHelper::GetProperty\n"));
DISPPARAMS dispparamsNoArgs = {NULL, NULL, , };
return p->Invoke(dwDispID, IID_NULL,
LOCALE_USER_DEFAULT, DISPATCH_PROPERTYGET,
&dispparamsNoArgs, pVar, NULL, NULL);
}
};
atlcomcli.h部分代码
上面这些其实也都是调用了Invoke函数,当然你如果不想用它帮你封装过的这些函数的话,你可以自行调用比上面这些更原始的Invoke,或者重新封装一下它。
总而言之,当你做这就事的时候一定要不停的查阅MSDN,没了它你就是在蒙着眼睛摸象加自欺欺人。