Xerces-C++学习之——查询修改XML文档 (转)

/*
* ===========================================================================
*
* Filename: ParseXML.cpp
*
* Description: This is an example of the use of Xerces-C++ operation XML.
*
* Version: 1.0
* Created: 03/01/2010 09:44:19 AM
* Revision: none
* Compiler: gcc
*
* Author: huabo (caodaijun), [e-mail]
* Company: feinno
*
* ===========================================================================
*/
#include <xercesc/util/PlatformUtils.hpp>
#include <xercesc/util/XMLString.hpp>
#include <xercesc/dom/DOM.hpp>
#include <xercesc/util/OutOfMemoryException.hpp>
#include <xercesc/framework/MemBufFormatTarget.hpp>
#include <xercesc/framework/StdOutFormatTarget.hpp>
#include <xercesc/framework/MemBufInputSource.hpp>
#include <xercesc/parsers/XercesDOMParser.hpp>

#include <string>

#if defined(XERCES_NEW_IOSTREAMS)
#include <iostream>
#else
#include <iostream.h>
#endif

XERCES_CPP_NAMESPACE_USE
class XStr
{
public:
XStr(const char* const toTranscode)
{
fUnicodeForm = XMLString::transcode(toTranscode);
}
~XStr()
{
XMLString::release(&fUnicodeForm);
}
const XMLCh* unicodeForm() const
{
return fUnicodeForm;
}
private:
XMLCh* fUnicodeForm;
};

#define X(str) XStr(str).unicodeForm()

std::string xml_string =
"<?xml version='1.0' encoding='UTF-8' standalone='yes' ?><corporation xmlns='com:cmcc:corporation' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='com:cmcc:corporation corporation.xsd'><eid>100000</eid><basic><corp_name>abcd</corp_name><corp_code/><c0/><short_name/><calling_code/><legal_representative/><address/><zip/><telephone/><fax/><contact/><proportion_code/><logo_crc/><employee_portrait_crc/><group_portrait_crc/><createtime/><opentime/><province_code/><vgop_code/><org_version/><source_code/><client_dept_version/><version_id/><contact_mp/></basic><rules><order_flag/><demo_flag/><useroperate_limit/><emp_portrait_flag/><iplmt/><dept_auth_switch/><sms_block/><sms_begin/><sms_end/><edit_status/><expire_time/></rules><accounts><scale_code/><customer_manager/><manager_phone/><deposit_bank/><bank_accounts/><password_paper_id/><group_code/><sms_code/><meeting_code/><fee_code/><cycle_code/><sharedisk_code/><sp_status/><updatetime/></accounts></corporation>";

std::string basic_string = "<basic><test>good</test></basic>";

int main(int argC, char*argV[])
{
// Initialize the XML4C2 system.
try
{
XMLPlatformUtils::Initialize();
}
catch(const XMLException& toCatch)
{
char *pMsg = XMLString::transcode(toCatch.getMessage());
XERCES_STD_QUALIFIER cerr << "Error during Xerces-c Initialization.\n"
<< " Exception message:"
<< pMsg;
XMLString::release(&pMsg);
return 1;
}

DOMImplementation* impl = DOMImplementationRegistry::getDOMImplementation(X("LS"));
DOMLSSerializer* theSerializer = ((DOMImplementationLS*)impl)->createLSSerializer();
DOMLSOutput *theOutputDesc = ((DOMImplementationLS*)impl)->createLSOutput();
MemBufFormatTarget* target = new MemBufFormatTarget();
theOutputDesc->setByteStream(target);

if (impl != NULL)
{
try
{

XercesDOMParser* parser = new XercesDOMParser();

MemBufInputSource* xml_mem = new MemBufInputSource(
(const XMLByte* )xml_string.c_str(),
xml_string.length(),
"xml",
false);
parser->parse( *xml_mem );
DOMDocument* xml_doc = parser->getDocument();
DOMElement* xml_root = xml_doc->getDocumentElement();
if (NULL == xml_root)
{
std::cout<< "Empty XML document!\n";
exit(1);
}
//输出整个文档
std::cout<< XMLString::transcode(theSerializer->writeToString((DOMNode* )xml_root))<< std::endl;

//输出XPATH指定的结点
DOMXPathNSResolver* resolver = xml_doc->createNSResolver(xml_root);
DOMXPathResult* result = xml_doc->evaluate(
X("/corporation/basic"),
xml_root,
resolver,
DOMXPathResult::ORDERED_NODE_SNAPSHOT_TYPE,
NULL);
result->snapshotItem(0);
DOMNode* curentNode = result->getNodeValue();
DOMNode* prevNode = curentNode->getParentNode();
theSerializer->write(curentNode, theOutputDesc);
std::cout<< target->getRawBuffer()<< std::endl;

//replace the basic child
MemBufInputSource* basic_mem = new MemBufInputSource(
(const XMLByte* )basic_string.c_str(),
basic_string.length(),
"basic",
false);
parser->parse( *basic_mem );
DOMDocument* basic_doc = parser->getDocument();
DOMElement* basic_root = basic_doc->getDocumentElement();
DOMNode* newnode = xml_doc->importNode((DOMNode* )basic_root, true);
prevNode->replaceChild(newnode, curentNode);

//再次输出整个文档
std::cout<< XMLString::transcode(theSerializer->writeToString((DOMNode* )xml_root))<< std::endl;

delete basic_mem;
delete xml_mem;
delete target;
delete parser;
result->release();
resolver->release();
theOutputDesc->release();
theSerializer->release();
}
catch(const OutOfMemoryException&)
{
XERCES_STD_QUALIFIER cerr << "OutOfMemoryException" << XERCES_STD_QUALIFIER endl;
}
catch (const DOMException& e)
{
XERCES_STD_QUALIFIER cerr << "DOMException code is: " << e.code << XERCES_STD_QUALIFIER endl;
}
catch (...)
{
XERCES_STD_QUALIFIER cerr << "An error occurred creating the document" << XERCES_STD_QUALIFIER endl;
}
}
else
{
XERCES_STD_QUALIFIER cerr << "Requested implementation is not supported" << XERCES_STD_QUALIFIER endl;
}

XMLPlatformUtils::Terminate();
return 0;
}

 

转：http://blog.chinaunix.net/uid-17240700-id-2813918.html

评论

1 楼 xiejanee 2014-08-15  

楼主：你好！我想请问下  你在代码中用DOMDocument* xml_doc = parser->getDocument();语句创建了doc 但是最后在清理内存的时候为什么没有将doc所指向的内存空间释放？
我在处理xml文件时遇到了一个问题 就是自己写的一个类中需要实现对xml文件的修改以及保存 所以代码中用到了xerces的dom方式对xml文件进行修改  代码中有paser以及doc的创建语句 ：
XercesDOMParser *parser = new XercesDOMParser;
xercesc_3_1::DOMDocument *doc = parser->getDocument();
在xml文件处理完后，想同时释放类对象中parser 以及 doc所指向的内存空间，此时就会报内存读取错误， 我是用doc->release();delete parser;这两条语句对两者进行空间清理的，但是若只调用其中的一个语句对相应指针的指向空间进行清理时，就不会报错，难道parser所指向的内存空间和doc说指向的内存空间有重叠部分吗，以至于两条语句会清理同一块内存区域？ 请楼主指教 谢谢。