What You Should Know About Dom4J and Dom4J

What You Should Know About Dom4J and Dom4J

Create a parser:

SAXReader reader = new SAXReader ();

Use the parser to read xml documents:
Document document = reader. read (new File ("input. xml "));

Get the root node of the document:

Element root = document. getRootElement ();

Interface inheritance structure:

Node ---

Branch

-- Document

-- Element

----

Attribute

 

NodeInterface

String	AsXML() AsXMLreturns the textual XML representation of this node. Converts a node to a string.
String	GetName() GetNamereturns the name of this node. Obtains the node name. If it is an element, the element name is obtained. If it is an attribute, the attribute name is obtained.
Short	GetNodeType() Returns the code according to the type of node. Obtains the Node type. Some static short constants are defined on the Node interface to indicate various types.
Element	GetParent() GetParentreturns the parent Element if this node supports the parent relationship or null if it is the root element or does not support the parent relationship. Obtain the parent node. If it is called by the root element, null is returned. If it is called by other elements, the parent element is returned. If it is called by the attribute, the elements attached to the attribute are returned.
String	GetText() Returns the text of this node. Return the node text. If it is an element, the TAG body is returned. If it is an attribute, the attribute value is returned.
List	SelectNodes(String xpathExpression) SelectNodesevaluates an XPath expression and returns the result as a List of Node instances or String instances depending on the XPath expression. Select a node using an xpath expression
Void	SetName(String name) Sets the text data of this node or this method will throw an UnsupportedOperationException if it is read-only. Set the node name. The element can change the name, but the attribute cannot. An UnsupportedOperationException is thrown.
Void	SetText(String text) Sets the text data of this node or this method will throw an UnsupportedOperationException if it is read-only. Set the node content. If it is an element, set the label body. If it is an attribute, set the attribute value.
Void	Write(Writer writer) Writewrites this node as the default XML notation for this node. Writes a node to an output stream. All elements and attributes are supported.

 

 

BranchInterface(ImplementedNodeInterface)

Void	Add(Element element) Adds the given Element to this branch. Add a subnode
Element	AddElement(QName qname) Adds a new Element node with the given QNameto this branch and returns a reference to the new node. Add a subnode with a given name and return a reference to the newly created node.
Int	IndexOf(Node node) Returns the index of the given node if it is a child node of this branch or-1 if the given node is not a child node. Obtains the position number of a given node in all direct points. If the node is not a subnode of this branch,-1 is returned.
Boolean	Remove(Element element) Removes the given Element if the node is an immediate child of this branch. Return a Boolean value indicating whether the deletion is successful.

 

ElementInterface (implementedBranch,NodeInterface)

Void	Add(Attribute attribute Attribute) Adds the given Attribute to this element. Add an attribute
Element	AddAttribute(QName qName, String value) Adds the attribute value of the given fully qualified name. Adds an attribute to an element, uses the given attribute name and attribute value, and returns the element
Element	AddAttribute(String name, String value) Adds the attribute value of the given local name. Add attribute to element
Attribute	Attribute(Int index) Returns the attribute at the specified indexGets Obtains the attribute of a specified position.
Attribute	Attribute(QName qName) Document me! Obtains the attributes of a specified name.
Iterator	AttributeIterator() Document me! Get attribute iterator
List	Attributes() Returns the Attributeinstances this element contains as a backed Listso that the attributes may be modified directly using the Listinterface. Obtains all the attributes of the element and returns a list.
String	AttributeValue(QName qName) This returns the attribute value for the attribute with the given fully qualified name or null if there is no such attribute or the empty string if the attribute value is empty. Obtains the value of the specified name attribute. If this attribute does not exist, null is returned. If this attribute exists but the attribute value is null, an empty string is returned.
Element	Element(QName qName) Returns the first element for the given fully qualified name. Obtains the child element of the specified name. If there are multiple child elements of the name, the first child element is returned.
Element	Element(String name) Returns the first element for the given fully qualified name. Obtains the child element of the specified name. If there are multiple child elements of the name, the first child element is returned.
Iterator	ElementIterator() Returns an iterator over all this elements child elements. Get child element iterator
Iterator	ElementIterator(QName qName) Returns an iterator over the elements contained in this element which match the given fully qualified name. Iterator for retrieving child elements of a specified name
List	Elements() Returns the elements contained in this element. Obtain all child elements and return them with a list
List	Elements(QName qName) Returns the elements contained in this element with the given fully qualified name. Obtain all the child elements of the specified name and return them with a list.
String	GetText() Returns the text value of this element without recursing through child elements. Get element TAG body
Boolean	Remove(Attribute attribute Attribute) Removes the given Attribute from this element. Remove attributes from an element
Void	SetAttributes(List attributes) Sets the attributes that this element contains Set all attributes in the list to this element.

 

AttributeInterface(ImplementedNodeInterface)

QName	GetQName() Returns the QName of this attribute which represents the local name, the qualified name and the Namespace. Get attribute name
String	GetValue() Returns the value of the attribute. Get Attribute Value
Void	SetValue(String value) Sets the value of this attribute or this method will throw an UnsupportedOperationException if it is read-only. Set attribute values

 

 

DocumentHelperClass

Static Attribute	CreateAttribute(Element owner, QName qname, String value) Create an Attribute
Static Document	CreateDocument() Create a Document
Static Document	CreateDocument(Element rootElement) Create a Document with a given element as the root element
	Static Element	CreateElement(QName qname) Create an Element with a given name
Static Document	ParseText(String text) ParseTextparses the given text as an XML document and returns the newly created Document. Convert a string to a Document

 

 

Write the nodeXMLFile

Method 1:

Call the write (Writerwriter) method provided by Node to output the Node to the stream by default:

Node. write (newFileWriter ("book. xml "));

Garbled problem:

Dom4j uses the encoding set of the encoding attribute declaration in the Document declaration when loading documents into memory for encoding, if the internal collation set used by writer is different from encoding when writer is output at this time, garbled characters may occur.

FileWriter uses the local code table (gb2312) of the operating system by default and cannot be changed.

In this case, you can use OutputStreamWriter (FileOutputStream ("filePath"), "UTF-8"); to encapsulate the Writer of a specified code table, so as to solve the garbled problem.

Method 2:

Use XMLWriter to write the Node:
XMLWriter writer = new XMLWriter (new FileWriter ("output. xml "));
Writer. write (node );
Writer. close ();

Garbled problem:

(1) When output in this way, XMLWriter first translates docuemnt in memory into a document in the UTF-8 format and outputs it in the input line. At this time, garbled characters may occur.

You can use OutputFormat to specify other encodings for XMLWriter conversion.

OutputFormat format = OutputFormat. createPrettyPrint ();

Format. setEncoding ("GBK ");
XMLWriterwriter = new XMLWriter (new FileWriter ("output. xml"), format );

(2) The encoding set used by Writer is different from the encoding set used when the document is loaded into memory, leading to garbled characters. You can use a byte stream or encapsulate the encoding stream specified by yourself (refer to method 1 ).