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我正在编写一个服务器，我想在我的 Java 客户端中使用 XML。我正在使用带有 XercesC 3.1.1 的 CygWin 进行开发测试，这工作正常（我用这个函数循环了 30000 并且没有崩溃）。但是，在我的目标机器上，它运行的是带有 XercesC 2.7 的 HP-UX。为了实现 XercesC 实现中的差异，我编写了一个单独的类来处理每个版本。

当我尝试使用 XercesC 2.7 运行代码时。当我尝试创建 DOMWriter 时，我总是得到一个 NULL 指针，而在再次尝试时，我总是得到一个 SIGABORT。

由于我在谷歌上找不到任何东西，我希望有人能阐明我在这里做错了什么。我一直在查看随 XercesC 源提供的示例代码，并且我也有一些来自其他程序员的生产代码，我看不出它有什么不同。

我尝试创建一个有点长的 SSCE，但它是我可以创建的最短样本。

xml_serialize.h

#ifndef XML_SERIALIZE_H_
#define XML_SERIALIZE_H_

#include <string>

#include <xercesc/util/PlatformUtils.hpp>
#include <xercesc/util/XMLString.hpp>
#include <xercesc/dom/DOM.hpp>
#if defined(XERCES_NEW_IOSTREAMS)
#include <iostream>
#else
#include <iostream.h>
#endif
#include <xercesc/util/OutOfMemoryException.hpp>

class XStr
{
public :
    // -----------------------------------------------------------------------
    //  Constructors and Destructor
    // -----------------------------------------------------------------------
    XStr(const char* const toTranscode)
    {
        // Call the private transcoding method
        fUnicodeForm = xercesc::XMLString::transcode(toTranscode);
    }

    ~XStr()
    {
     xercesc::XMLString::release(&fUnicodeForm);
    }


    // -----------------------------------------------------------------------
    //  Getter methods
    // -----------------------------------------------------------------------
    const XMLCh* unicodeForm() const
    {
        return fUnicodeForm;
    }

private :
    // -----------------------------------------------------------------------
    //  Private data members
    //
    //  fUnicodeForm
    //      This is the Unicode XMLCh format of the string.
    // -----------------------------------------------------------------------
    XMLCh*   fUnicodeForm;
};

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

std::string fromXMLString(XMLCh *oXMLString);

class XMLSerialize
{
private:
        xercesc::DOMImplementation *mImpl;

protected:
        xercesc::DOMImplementation *getDOMImplementation(void);

public:
    XMLSerialize(void);
    virtual ~XMLSerialize(void);

public:

    /**
     * Creates an empty DOM
     */
    xercesc::DOMDocument *createDocument(const std::string &oDocumentName);

    /**
     * Parses an XML from a string.
     */
    xercesc::DOMDocument *parseDocument(const std::string &oDocumentName, std::string const &oReferenceId);

    /**
     * Serializes the document into a string
     */
    int serialize(xercesc::DOMDocument *oDocument, std::string &oXMLOut, bool bDocumentRelease = true);
};

#endif /* XML_SERIALIZE_H_ */

xml_serialize.cpp

#include <xercesc/util/XMLString.hpp>
#include <xercesc/dom/DOM.hpp>
#include <xercesc/util/TransService.hpp>
#include <xercesc/framework/MemBufFormatTarget.hpp>
#include <xercesc/util/OutOfMemoryException.hpp>

#include <sstream>
#include <vector>
#include <iostream>

#include "xml_serialize.h"

int serializeEnvironment(void);
XMLSerialize *serializer = NULL;

XMLSerialize::XMLSerialize()
{
    mImpl = xercesc::DOMImplementationRegistry::getDOMImplementation(X("Core"));
}

XMLSerialize::~XMLSerialize()
{
}

xercesc::DOMDocument *XMLSerialize::createDocument(const std::string &oDocumentName)
{
    if(mImpl == NULL)
        return NULL;

    xercesc::DOMDocument *doc = mImpl->createDocument(
            0,                      // root element namespace URI.
            X(oDocumentName.c_str()),       // root element name
            0);                 // document type object (DTD).

    if(doc == NULL)
        return NULL;

    return doc;
}

int XMLSerialize::serialize(xercesc::DOMDocument *oDocument, std::string &oXMLOut, bool bDocumentRelease)
{
    int result = 0;
    XMLCh *xmlUnicode = NULL;
    char *strXML = NULL;
    xercesc::DOMWriter *serializer = NULL;

    if(mImpl == NULL)
    {
        oXMLOut = "ERROR: XercesC DOMImplementationRegistry not initialized";
        result = 1;
        goto Quit;
    }

    serializer = ((xercesc::DOMImplementationLS*)mImpl)->createDOMWriter();
    if(serializer == NULL)
    {
        oXMLOut = "ERROR: XercesC unable to instantiate a DOMWriter!";
        result = 2;
        goto Quit;
    }

    xmlUnicode = serializer->writeToString(*oDocument);
    strXML = xercesc::XMLString::transcode(xmlUnicode);
    oXMLOut = strXML;

    if(bDocumentRelease == true)
        oDocument->release();

    result = 0;

Quit:
    if(strXML != NULL)
        xercesc::XMLString::release(&strXML);

    if(xmlUnicode != NULL)
        xercesc::XMLString::release(&xmlUnicode);

    if(serializer != NULL)
        serializer->release();

    return result;
}

int serializeEnvironment(void)
{
    int errorCode = 0;
    xercesc::DOMElement *rootElem = NULL;
    xercesc::DOMElement *item = NULL;
    xercesc::DOMElement *element = NULL;
    xercesc::DOMText *nameNode = NULL;
    xercesc::DOMCDATASection *dataNode = NULL;
    std::string xml;

    try
    {
        xercesc::DOMDocument *doc = serializer->createDocument("EnvironmentList");
        if(doc == NULL)
            return 1;

        rootElem = doc->getDocumentElement();
        std::vector<std::pair<std::string, std::string> > env;
        for(int i = 0; i < 5; i++)
        {
            std::string key;
            std::string value;

            std::stringstream ss;
            ss << "KEY";
            ss << i;
            ss >> key;
            ss.clear();

            ss << "VALUE";
            ss << i;
            ss >> value;
            ss.clear();

            env.push_back(std::make_pair(key, value));
        }

        for(std::vector<std::pair<std::string, std::string> >::const_iterator it = env.begin(); it != env.end(); ++it)
        {
            std::pair<std::string, std::string>entry = *it;
            std::string name = entry.first;
            std::string value = entry.second;

            if(value.empty())
                value = "";

            item = doc->createElement(X("item"));
            rootElem->appendChild(item);

            element = doc->createElement(X("item"));
            nameNode = doc->createTextNode(X(name.c_str()));
            item->appendChild(element);
            element->appendChild(nameNode);

            element = doc->createElement(X("item"));
            dataNode = doc->createCDATASection(X(value.c_str()));
            item->appendChild(element);
            element->appendChild(dataNode);
        }

        errorCode = serializer->serialize(doc, xml);
        std::cout << xml << std::endl;

        doc->release();
        errorCode = 0;
    }
    catch (const xercesc::OutOfMemoryException&)
    {
        XERCES_STD_QUALIFIER cerr << "OutOfMemoryException" << XERCES_STD_QUALIFIER endl;
        errorCode = 2;
    }
    catch (const xercesc::DOMException& e)
    {
        XERCES_STD_QUALIFIER cerr << "DOMException code is:  " << e.code << XERCES_STD_QUALIFIER endl;
        errorCode = 3;
    }
    catch (...)
    {
        XERCES_STD_QUALIFIER cerr << "An error occurred creating the document" << XERCES_STD_QUALIFIER endl;
        errorCode = 4;
    }

    return errorCode;
}

int main()
{
    xercesc::XMLPlatformUtils::Initialize();

   serializer = new XMLSerialize();

   int error = 0;
   for(int i = 0; i < 2; i++)
   {
    std::cout << "Serializing:" << i << " ... " << std::endl;
    if((error = serializeEnvironment()) != 0)
        std::cout << "ERROR" << error << std::endl;

    std::cout << "Done" << std::endl;
   }

    xercesc::XMLPlatformUtils::Terminate();

    return 0;
}

输出

Serializing:0 ... 
ERROR: XercesC unable to instantiate a DOMWriter!
Done
Serializing:1 ... 
aCC runtime: pure virtual function called for class "xercesc_2_7::DOMImplementationLS".
Abort(coredump)

更新

我终于设法为 cygwin 编译了 2.7 并在那里测试了上面的代码。这工作正常，所以 HP-UX 环境一定有问题。

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1 回答 1

0

我正在编译代码，gcc显然 xerces 库是用aCC. 所以现在我切换到aCC我的makefile，现在它可以工作了。

人们应该期望生成的库是兼容的，但显然情况并非如此。所以上面的代码其实是正确的。

于 2013-07-31T14:19:15.493 回答