Using qdomdocument to manipulate XML files in QT

Catalog

The header file

Associated files

XML Writing files

（1） establish xml Document format header

（2） Create root node element labels

（3） Create child node element labels

（4） Set tag properties

（5） Set label content

（6） preservation xml file

XML File analysis  

（1） Find all node elements for a specific tagName

（2） QDomNodeList Class introduction

（3）QDomNode Class method

（4） Traversal node

（5） QDomElement And  QDomNode

（6） obtain QDomNode Two methods of attribute value

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The header file

qmake: QT += xml

Header: #include<QDomDocument>

QDomDocument --> xml The file pointer

Associated files

QFile file(filePath);

file.open(QIODevice::WriteOnly);

QDomDocument doc;

doc.setContent(&file);

XML Writing files

（1） establish xml Document format header

QDomProcessingInstruction ins;
ins = doc.createProcessingInstruction("xml", "version = \'1.0\' encoding=\'utf-8\'");

（2） Create root node element labels

  QDomElement root = doc.createElement("tagname");
  doc.appendChild(root);

（3） Create child node element labels

QDomElement dateEmt = doc.createElement("childTagName");

root.appendChild(dateEmt);

（4） Set tag properties

QDomElement dateEmt = doc.createElement("cim:Company");

// Create attribute name  
QDomAttr dateAttr = doc.createAttribute(" Property name ");
dateAttr.setNodeValue(" Property content ”);

dateEmt.setAttributeNode(dateAttr); // Set tag properties

（5） Set label content

QDomText text = doc.createTextNode("xxx");
dateEmt.appendChild(text);

（6） preservation xml file

QTextStream stream(&file);
doc.save(stream, 4); // Parameters 2 by Labeled tab Indent value

XML File analysis  

（1） Find all node elements for a specific tagName

QDomNodeList nodeList = doc.elementsByTagName(" Tag name ")

（2） QDomNodeList Class introduction

QDomNodeList Class

QDomNodeList Class is QDomNode List of objects .

Header:	#include <QDomNodeList>
qmake:	QT += xml

• List of all members , Including inherited members

Note: All functions in this class are reentrant.

Public Functions

	QDomNodeList()
	QDomNodeList(const QDomNodeList &n)
	~QDomNodeList()
QDomNode	at(int index) const
int	count() const
bool	isEmpty() const
QDomNode	item(int index) const
int	length() const
int	size() const
bool	operator!=(const QDomNodeList &n) const
QDomNodeList &	operator=(const QDomNodeList &n)
bool	operator==(const QDomNodeList &n) const

Detailed description

QDomNodeList Class is QDomNode List of objects .

The list can be through QDomDocument：：elementsByTagName（） and QDomNode：：childNodes（） get . Document object model （DOM） These lists are required to be “ Activities of the ”： Whenever you change the underlying document , The contents of the list will be updated .

have access to item（） Get a specific node from the list . The number of items in the list is determined by length（） return

（3）QDomNode Class method

	QDomNode()
	QDomNode(const QDomNode &n)
	~QDomNode()
QDomNode	appendChild(const QDomNode &newChild)
QDomNamedNodeMap	attributes() const
QDomNodeList	childNodes() const
void	clear()
QDomNode	cloneNode(bool deep = true) const
int	columnNumber() const
QDomNode	firstChild() const
QDomElement	firstChildElement(const QString &tagName = QString()) const
bool	hasAttributes() const
bool	hasChildNodes() const
QDomNode	insertAfter(const QDomNode &newChild, const QDomNode &refChild)
QDomNode	insertBefore(const QDomNode &newChild, const QDomNode &refChild)
bool	isAttr() const
bool	isCDATASection() const
bool	isCharacterData() const
bool	isComment() const
bool	isDocument() const
bool	isDocumentFragment() const
bool	isDocumentType() const
bool	isElement() const
bool	isEntity() const
bool	isEntityReference() const
bool	isNotation() const
bool	isNull() const
bool	isProcessingInstruction() const
bool	isSupported(const QString &feature, const QString &version) const
bool	isText() const
QDomNode	lastChild() const
QDomElement	lastChildElement(const QString &tagName = QString()) const
int	lineNumber() const
QString	localName() const
QDomNode	namedItem(const QString &name) const
QString	namespaceURI() const
QDomNode	nextSibling() const
QDomElement	nextSiblingElement(const QString &tagName = QString()) const
QString	nodeName() const
NodeType	nodeType() const
QString	nodeValue() const
void	normalize()
QDomDocument	ownerDocument() const
QDomNode	parentNode() const
QString	prefix() const
QDomNode	previousSibling() const
QDomElement	previousSiblingElement(const QString &tagName = QString()) const
QDomNode	removeChild(const QDomNode &oldChild)
QDomNode	replaceChild(const QDomNode &newChild, const QDomNode &oldChild)
void	save(QTextStream &stream, int indent, EncodingPolicy encodingPolicy = QDomNode::EncodingFromDocument) const
void	setNodeValue(const QString &v)
void	setPrefix(const QString &pre)
QDomAttr	toAttr() const
QDomCDATASection	toCDATASection() const
QDomCharacterData	toCharacterData() const
QDomComment	toComment() const
QDomDocument	toDocument() const
QDomDocumentFragment	toDocumentFragment() const
QDomDocumentType	toDocumentType() const
QDomElement	toElement() const
QDomEntity	toEntity() const
QDomEntityReference	toEntityReference() const
QDomNotation	toNotation() const
QDomProcessingInstruction	toProcessingInstruction() const
QDomText	toText() const
bool	operator!=(const QDomNode &n) const
QDomNode &	operator=(const QDomNode &n)
bool	operator==(const QDomNode &n) const

（4） Traversal node

Use firstChild（） Get the first child node of the node （ If there is ）, And use nextSibling（） Traversal .

（5） QDomElement And  QDomNode

I understand it ： QDomElement and QDomNode It's all nodes , Difference is that QDomElement Is a separate node （ That is, when there are no sub tags ）, have access to tagName() and text() Method to get the name and content of the node . QDomNode have access to toElement() Turn into QDomElement type

（6） obtain QDomNode Two methods of attribute value

QDomNode node;

① QString value = node.attributes().namedItem(" Property name ").nodeValue()

② QString value = QDomElement elem = node.toElement().attribute( " Property name " );