使用MsXML存取XML（2）

@H_403_14@与JavaScript相比而言，在C++中调用COM比较麻烦，MsXML库是一组COM动态库，这意味VisualC++应用程序必须以COM调用方式调用MsXML组件。

@H_403_14@下面是实现存取persons.xml文件的VisualC++版本。

@H_403_14@需要导入“msxml4.dll”组件库

@H_403_14@【程序6-8】使用MsXML读写XML文件

@H_403_14@1.01#include"stdafx.h"

@H_403_14@2.02#include"comutil.h"

@H_403_14@3.03#include<clocale>

@H_403_14@4.04

@H_403_14@5.05#import"msxml4.dll"

@H_403_14@6.06

@H_403_14@7.07voidWritePerson(MSXML2::IXMLDOMDocument2PtrpDocument,

@H_403_14@8.MSXML2::IXMLDOMNodePtrpParentNode,CStringname,longage)

@H_403_14@9.08{

@H_403_14@10.09//创建一个<person>节点

@H_403_14@11.10MSXML2::IXMLDOMElementPtrpPersonNode=
pDocument->createElement(_T("person"));

@H_403_14@12.11pParentNode->appendChild(pPersonNode);

@H_403_14@13.12

@H_403_14@14.13//写入name

@H_403_14@15.14MSXML2::IXMLDOMElementPtrpPersonNameNode=
pDocument->createElement(_T("name"));

@H_403_14@16.15pPersonNameNode->text=_bstr_t(name);

@H_403_14@17.16

@H_403_14@18.17//写入age

@H_403_14@19.18MSXML2::IXMLDOMElementPtrpPersonAgeNode=
pDocument->createElement(_T("age"));

@H_403_14@20.19pPersonAgeNode->text=_bstr_t(age);

@H_403_14@21.20

@H_403_14@22.21pPersonNode->appendChild(pPersonNameNode);

@H_403_14@23.22pPersonNode->appendChild(pPersonAgeNode);

@H_403_14@24.23}

@H_403_14@25.24

@H_403_14@26.25voidWritePersons()

@H_403_14@27.26{

@H_403_14@28.27MSXML2::IXMLDOMDocument2PtrpXMLDocument;

@H_403_14@29.28pXMLDocument.CreateInstance(__uuidof(MSXML2::DOMDocument));

@H_403_14@30.29MSXML2::IXMLDOMElementPtrpPersonsNode=

@H_403_14@31.pXMLDocument->createElement(_T("persons"));

@H_403_14@32.30pXMLDocument->appendChild(pPersonsNode);

@H_403_14@33.31

@H_403_14@34.32WritePerson(pXMLDocument,pPersonsNode,_T("佟湘玉"),28);

@H_403_14@35.33WritePerson(pXMLDocument,255)">"白展堂"),27);

@H_403_14@36.34

@H_403_14@37.35pXMLDocument->save(_T("persons.xml"));

@H_403_14@38.36}

@H_403_14@39.37

@H_403_14@40.38voidReadPersons()

@H_403_14@41.39{

@H_403_14@42.40MSXML2::IXMLDOMDocument2PtrpXMLDocument;

@H_403_14@43.41pXMLDocument.CreateInstance(__uuidof(MSXML2::DOMDocument));

@H_403_14@44.42

@H_403_14@45.43pXMLDocument->load(_T("persons.xml"));

@H_403_14@46.44

@H_403_14@47.45MSXML2::IXMLDOMElementPtrpRootNode=
pXMLDocument->documentElement;

@H_403_14@48.46//查找<person>节点

@H_403_14@49.47MSXML2::IXMLDOMNodeListPtrpPersonNodes=
pRootNode->selectNodes(_T("person"));

@H_403_14@50.48

@H_403_14@51.49CStrings;

@H_403_14@52.50longsize=pPersonNodes->length;

@H_403_14@53.51

@H_403_14@54.52for(inti=0;i<size;i++)

@H_403_14@55.53{

@H_403_14@56.54MSXML2::IXMLDOMNodePtrpPersonNode=
pPersonNodes->item[i];

@H_403_14@57.55

@H_403_14@58.56MSXML2::IXMLDOMNodePtrpNameNode=
pPersonNode->selectSingleNode(_T("name"));

@H_403_14@59.57MSXML2::IXMLDOMNodePtrpAgeNode=
pPersonNode->selectSingleNode(_T("age"));

@H_403_14@60.58

@H_403_14@61.59s.Format(_T("%sname:%s\tage:%s\r\n"),
s,(LPCTSTR)pNameNode->

@H_403_14@62.text,87)">LPCTSTR)pAgeNode->text);

@H_403_14@63.60}

@H_403_14@64.61

@H_403_14@65.62_tprintf(s);

@H_403_14@66.63}

@H_403_14@67.64

@H_403_14@68.65int_tmain()

@H_403_14@69.66{

@H_403_14@70.67setlocale(LC_ALL,"chs");

@H_403_14@71.68

@H_403_14@72.69HRESULThr;

@H_403_14@73.70hr=::CoInitialize(NULL);

@H_403_14@74.71

@H_403_14@75.72WritePersons();

@H_403_14@76.73ReadPersons();

@H_403_14@77.74

@H_403_14@78.75::CoUninitialize();

@H_403_14@79.76return0;77}

@H_403_14@运行结果如图6-27所示。

@H_403_14@图6-27运行结果

@H_403_14@在VisualC++中，调用COM组件比较省力、安全的办法是使用#import方式。另外，MsXML的版本不同，其提供的DLL文件名也不同，如MSXML4.0对应的DLL为"msxml4.dll"。细心的读者可能会发现，一旦在程序中导入了msxml4.dll并build（生成）一次项目，在程序中就可以自动引入一些类，如：MSXML2::IXMLDOMDocument2Ptr，MSXML2是一个C++名字空间，IXMLDOMDocument2Ptr则是一个封装了IXMLDOMDocument对象操作的智能指针类。好奇的读者可以选择"IXMLDOMDocument2Ptr"，并查看其定义，就可以跟踪到Debug目录下一个叫着msxml4.tlh的头文件，它是由VisualC++从msxml4.dll中自动提取并生成的C++头文件，与此一起生成的还有其他的文件，如msxml4.tli等。