演示:如何创建DOM文档

Question

我想创建一个DOMDocument与经验，但我得到一个空指针的错误

此时:

DOMImplementation* impl = DOMImplementationRegistry::getDOMImplementation(tempStr, 0);

错误是:

xercesc_3_2: domImplementationnullptr

我的代码是:

//
//  Create a small document tree
//
{
XMLCh tempStr[100];
XMLString::transcode("Range", tempStr, 99);
DOMImplementation* impl = DOMImplementationRegistry::getDOMImplementation(tempStr, 0);
XMLString::transcode("root", tempStr, 99);
DOMDocument*   doc = impl->createDocument(0, tempStr, 0);
DOMElement*   root = doc->getDocumentElement();
XMLString::transcode("FirstElement", tempStr, 99);
DOMElement*   e1 = doc->createElement(tempStr);
root->appendChild(e1);
XMLString::transcode("SecondElement", tempStr, 99);
DOMElement*   e2 = doc->createElement(tempStr);
root->appendChild(e2);
XMLString::transcode("aTextNode", tempStr, 99);
DOMText*       textNode = doc->createTextNode(tempStr);
e1->appendChild(textNode);
// optionally, call release() to release the resource associated with the range after done
DOMRange* range = doc->createRange();
range->release();
// removedElement is an orphaned node, optionally call release() to release associated resource
DOMElement* removedElement = root->removeChild(e2);
removedElement->release();
// no need to release this returned object which is owned by implementation
XMLString::transcode("*", tempStr, 99);
DOMNodeList*    nodeList = doc->getElementsByTagName(tempStr);
// done with the document, must call release() to release the entire document resources
doc->release();
};

取自https://xerces.apache.org/xerces-c/program-dom-3.html

我错在哪里?我该如何解决这个问题?

谢谢

Answer 1

xercesc_3_2::XMLPlatformUtils::Initialize();
xercesc_3_2::DOMDocument* domDocument = NULL;
xercesc_3_2::DOMDocumentType* doc_domDocument = NULL;
xercesc_3_2::DOMElement* root;
xercesc_3_2::DOMElement* child1;
xercesc_3_2::DOMElement* child2;
xercesc_3_2::DOMImplementation* domImplementation = NULL;
domImplementation = 
xercesc_3_2::DOMImplementationRegistry::getDOMImplementation(xercesc_3_2::XMLString::transcode(""));
if (domImplementation == NULL) {
cout << "Vuoto" << endl;
}
domDocument = domImplementation->createDocument(0, xercesc_3_2::XMLString::transcode("xml"), doc_domDocument);
root = domDocument->getDocumentElement();
child1 = domDocument->createElement(xercesc_3_2::XMLString::transcode("Document"));
root->appendChild(child1);
cout << "debug node: " << xercesc_3_2::XMLString::transcode(child1->getTagName()) << endl;
child2 = domDocument->createElement(xercesc_3_2::XMLString::transcode("name"));
child2->appendChild(domDocument->createTextNode(xercesc_3_2::XMLString::transcode("1")));
child1->appendChild(child2);
cout << "debug node: " << xercesc_3_2::XMLString::transcode(child2->getTagName()) << endl;
child2 = domDocument->createElement(xercesc_3_2::XMLString::transcode("styleUrl"));
child2->appendChild(domDocument->createTextNode(xercesc_3_2::XMLString::transcode("0")));
child1->appendChild(child2);
cout << "debug node: " << xercesc_3_2::XMLString::transcode(child2->getTagName()) << endl;

和写入文件:

const int ABSOLUTE_PATH_FILENAME_PREFIX_SIZE = 9;
//Return the first registered implementation that has the desired features. In this case, we are after a DOM implementation that has the LS feature... or Load/Save.
xercesc_3_2::DOMImplementation* implementation = xercesc_3_2::DOMImplementationRegistry::getDOMImplementation(xercesc_3_2::XMLString::transcode("LS"));
// Create a DOMLSSerializer which is used to serialize a DOM tree into an XML document.
xercesc_3_2::DOMLSSerializer* serializer = ((xercesc_3_2::DOMImplementationLS*)implementation)->createLSSerializer();
// Make the output more human readable by inserting line feeds.
if (serializer->getDomConfig()->canSetParameter(xercesc_3_2::XMLUni::fgDOMWRTFormatPrettyPrint, true))
serializer->getDomConfig()->setParameter(xercesc_3_2::XMLUni::fgDOMWRTFormatPrettyPrint, true);
// The end-of-line sequence of characters to be used in the XML being written out. 
serializer->setNewLine(xercesc_3_2::XMLString::transcode("rn"));
// Convert the path into Xerces compatible XMLCh*.
XMLCh* tempFilePath = xercesc_3_2::XMLString::transcode(fileName.c_str());
// Specify the target for the XML output.
xercesc_3_2::XMLFormatTarget* formatTarget = new xercesc_3_2::LocalFileFormatTarget(tempFilePath);
//XMLFormatTarget *myFormTarget = new StdOutFormatTarget();
// Create a new empty output destination object.
xercesc_3_2::DOMLSOutput* output = ((xercesc_3_2::DOMImplementationLS*)implementation)->createLSOutput();
// Set the stream to our target.
output->setByteStream(formatTarget);
// Write the serialized output to the destination.
serializer->write(domDocument, output);
// Cleanup.
serializer->release();
xercesc_3_2::XMLString::release(&tempFilePath);
delete formatTarget;
output->release();