SAX解析XML文件

1. 实现ISAXContentHandler（startElement，characters，endElement）。
2. 初始化ISAXXMLReader， 传入ISAXContentHandler。
3. 解析XML文件。

<order id="ord123456">
 <address>
  <zip>98052</zip>
 </address>
</order>

#include <msxml2.h>
#include <stdio.h>


class SAXContentHandlerImpl : public ISAXContentHandler  
{
public:
    SAXContentHandlerImpl();
    virtual ~SAXContentHandlerImpl();

        // This must be correctly implemented, if your handler must be a COM Object (in this example it does not)
        long __stdcall QueryInterface(const struct _GUID &,void ** );
        unsigned long __stdcall AddRef(void);
        unsigned long __stdcall Release(void);

        virtual HRESULT STDMETHODCALLTYPE putDocumentLocator( 
            /* [in] */ ISAXLocator __RPC_FAR *pLocator);
        
        virtual HRESULT STDMETHODCALLTYPE startDocument( void);
        
        virtual HRESULT STDMETHODCALLTYPE endDocument( void);
        
        virtual HRESULT STDMETHODCALLTYPE startPrefixMapping( 
            /* [in] */ const wchar_t __RPC_FAR *pwchPrefix,
            /* [in] */ int cchPrefix,
            /* [in] */ const wchar_t __RPC_FAR *pwchUri,
            /* [in] */ int cchUri);
        
        virtual HRESULT STDMETHODCALLTYPE endPrefixMapping( 
            /* [in] */ const wchar_t __RPC_FAR *pwchPrefix,
            /* [in] */ int cchPrefix);
        
        virtual HRESULT STDMETHODCALLTYPE startElement( 
            /* [in] */ const wchar_t __RPC_FAR *pwchNamespaceUri,
            /* [in] */ int cchNamespaceUri,
            /* [in] */ const wchar_t __RPC_FAR *pwchLocalName,
            /* [in] */ int cchLocalName,
            /* [in] */ const wchar_t __RPC_FAR *pwchRawName,
            /* [in] */ int cchRawName,
            /* [in] */ ISAXAttributes __RPC_FAR *pAttributes);
        
        virtual HRESULT STDMETHODCALLTYPE endElement( 
            /* [in] */ const wchar_t __RPC_FAR *pwchNamespaceUri,
            /* [in] */ int cchNamespaceUri,
            /* [in] */ const wchar_t __RPC_FAR *pwchLocalName,
            /* [in] */ int cchLocalName,
            /* [in] */ const wchar_t __RPC_FAR *pwchRawName,
            /* [in] */ int cchRawName);
        
        virtual HRESULT STDMETHODCALLTYPE characters( 
            /* [in] */ const wchar_t __RPC_FAR *pwchChars,
            /* [in] */ int cchChars);
        
        virtual HRESULT STDMETHODCALLTYPE ignorableWhitespace( 
            /* [in] */ const wchar_t __RPC_FAR *pwchChars,
            /* [in] */ int cchChars);
        
        virtual HRESULT STDMETHODCALLTYPE processingInstruction( 
            /* [in] */ const wchar_t __RPC_FAR *pwchTarget,
            /* [in] */ int cchTarget,
            /* [in] */ const wchar_t __RPC_FAR *pwchData,
            /* [in] */ int cchData);
        
        virtual HRESULT STDMETHODCALLTYPE skippedEntity( 
            /* [in] */ const wchar_t __RPC_FAR *pwchName,
            /* [in] */ int cchName);

private:
	int indent;
};

SAXContentHandlerImpl::SAXContentHandlerImpl()
:indent(0)
{
}
SAXContentHandlerImpl::~SAXContentHandlerImpl()
{
}
HRESULT STDMETHODCALLTYPE SAXContentHandlerImpl::putDocumentLocator( 
            /* [in] */ ISAXLocator __RPC_FAR *pLocator
            )
{
    return S_OK;
}
        
HRESULT STDMETHODCALLTYPE SAXContentHandlerImpl::startDocument()
{
	wprintf(L"\nStart document!\n");
    return S_OK;
}
        
HRESULT STDMETHODCALLTYPE SAXContentHandlerImpl::endDocument( void)
{
	wprintf(L"\nEnd document!\n");
    return S_OK;
}
        
HRESULT STDMETHODCALLTYPE SAXContentHandlerImpl::startPrefixMapping( 
            /* [in] */ const wchar_t __RPC_FAR *pwchPrefix,
            /* [in] */ int cchPrefix,
            /* [in] */ const wchar_t __RPC_FAR *pwchUri,
            /* [in] */ int cchUri)
{
    return S_OK;
}
        
HRESULT STDMETHODCALLTYPE SAXContentHandlerImpl::endPrefixMapping( 
            /* [in] */ const wchar_t __RPC_FAR *pwchPrefix,
            /* [in] */ int cchPrefix)
{
    return S_OK;
}
        
HRESULT STDMETHODCALLTYPE SAXContentHandlerImpl::startElement( 
            /* [in] */ const wchar_t __RPC_FAR *pwchNamespaceUri,
            /* [in] */ int cchNamespaceUri,
            /* [in] */ const wchar_t __RPC_FAR *pwchLocalName,
            /* [in] */ int cchLocalName,
            /* [in] */ const wchar_t __RPC_FAR *pwchRawName,
            /* [in] */ int cchRawName,
            /* [in] */ ISAXAttributes __RPC_FAR *pAttributes)
{
	HRESULT hr = S_OK;
	
	for(int i=0; i<indent; ++i)
	{	
		wprintf(L"\t");
	}
	++indent;

	wprintf(L"<%s",pwchLocalName);

	int attributeNumber = 0;
	pAttributes->getLength(&attributeNumber);

	const wchar_t * attributeName = NULL;
	const wchar_t * valueName = NULL;
	int attributeNameLength = 0;
	int valueNameLength = 0;;
	
	wchar_t nameCache[64] = {0};

	for ( int i=0; i<attributeNumber; i++ ) 
	{
		pAttributes->getLocalName(i,&attributeName,&attributeNameLength);
		memset(nameCache, 0, 64);
		wcsncpy(nameCache, attributeName, attributeNameLength);
		wprintf(L" %s=", nameCache);

		pAttributes->getValue(i,&valueName,&valueNameLength);
		memset(nameCache, 0, 64);
		wcsncpy(nameCache, valueName, valueNameLength);
		wprintf(L"\"%s\"", nameCache);
	}
	printf(">\n");
	
    return hr;
}
       
HRESULT STDMETHODCALLTYPE SAXContentHandlerImpl::endElement( 
            /* [in] */ const wchar_t __RPC_FAR *pwchNamespaceUri,
            /* [in] */ int cchNamespaceUri,
            /* [in] */ const wchar_t __RPC_FAR *pwchLocalName,
            /* [in] */ int cchLocalName,
            /* [in] */ const wchar_t __RPC_FAR *pwchRawName,
            /* [in] */ int cchRawName)
{
	--indent;
	for(int i=0; i<indent; ++i)
	{	
		wprintf(L"\t");
	}

	wchar_t nameCache[64] = {0};
	wcsncpy(nameCache, pwchLocalName, cchLocalName);
	wprintf(L"</%s>\n", nameCache);

    return S_OK;
}
        
HRESULT STDMETHODCALLTYPE SAXContentHandlerImpl::characters( 
            /* [in] */ const wchar_t __RPC_FAR *pwchChars,
            /* [in] */ int cchChars)
{
	wchar_t nameCache[64] = {0};
	wcsncpy(nameCache, pwchChars, cchChars);

	if(nameCache[0] == L' ' || nameCache[0]==L'\n')
		return S_OK;

	for(int i=0; i<indent-1; ++i)
	{	
		wprintf(L"\t");
	}

	wprintf(L"%s\n", nameCache);
    return S_OK;
}

HRESULT STDMETHODCALLTYPE SAXContentHandlerImpl::ignorableWhitespace( 
            /* [in] */ const wchar_t __RPC_FAR *pwchChars,
            /* [in] */ int cchChars)
{
    return S_OK;
}

HRESULT STDMETHODCALLTYPE SAXContentHandlerImpl::processingInstruction( 
            /* [in] */ const wchar_t __RPC_FAR *pwchTarget,
            /* [in] */ int cchTarget,
            /* [in] */ const wchar_t __RPC_FAR *pwchData,
            /* [in] */ int cchData)
{
    return S_OK;
}
        
HRESULT STDMETHODCALLTYPE SAXContentHandlerImpl::skippedEntity( 
            /* [in] */ const wchar_t __RPC_FAR *pwchVal,
            /* [in] */ int cchVal)
{
    return S_OK;
}

long __stdcall SAXContentHandlerImpl::QueryInterface(const struct _GUID &riid,void ** ppvObject)
{
    return 0;
}

unsigned long __stdcall SAXContentHandlerImpl::AddRef()
{
    return 0;
}

unsigned long __stdcall SAXContentHandlerImpl::Release()
{
    return 0;
}

int main()
{
	CoInitialize(NULL); 
	ISAXXMLReader* pRdr = NULL;

	HRESULT hr = CoCreateInstance(
                        __uuidof(SAXXMLReader), 
                        NULL, 
                        CLSCTX_ALL, 
                        __uuidof(ISAXXMLReader), 
                        (void **)&pRdr);

	if(!FAILED(hr)) 
	{
		SAXContentHandlerImpl * pMc = new SAXContentHandlerImpl();
		hr = pRdr->putContentHandler(pMc);

		const wchar_t* URL = L"C:\\sample.xml";
		wprintf(L"\nParsing document: %s\n", URL);
      
		hr = pRdr->parseURL(URL);
		printf("\nParse result code: %08x\n\n",hr);

		pRdr->Release();
		delete pMc;
	}
	else 
	{
		printf("\nError %08X\n\n", hr);
	}

	CoUninitialize();
    return 0;
}