[Path to Java Development] (12) Parse XML documents using JDOM and DOM4J

[Path to Java Development] (12) Parse XML documents using JDOM and DOM4J
1. parse XML documents using JDOM1.1 Introduction JDOM is an open-source project. Based on the tree structure, JDOM uses JAVA-only technology to parse, generate, serialize, and perform multiple operations on XML documents. JDOM directly serves JAVA programming. It effectively integrates the functions of SAX and DOM by taking advantage of the many features of the more powerful JAVA language (method overloading, set concepts, and ing. In terms of use design, try to hide the complexity of the original XML Process. Using JDOM to process XML documents is easy and simple. JDOM help documentation: http://www.jdom.org/docs/apidocs/ Jar package: Click to open the link 1.2 parsing step (1) create a SAXBuilder object

SAXBuilder saxBuilder = new SAXBuilder();(2) create an input stream object and load the XML document to the input stream.

FileInputStream inputStream = new FileInputStream("D:\\bookstore.xml");(3) load the input stream to saxBuilder by using the build method of the saxBuilder object (note: the Document referenced package is org. jdom2.Document ;)

Document document = saxBuilder.build(inputStream);(4) Get the root node of the XML document through the document Object

Element rootElement = document.getRootElement();(5) obtain the subnode set under the root node based on the Root Node

List bookList = rootElement.getChildren(); (6) retrieving attribute node sets based on nodes

List attrList = book.getAttributes();(7) obtain the node name and Value Based on the node (element node or attribute node)

// Attribute name node.getName(); // Attribute Value node.getValue();1.3 Main method (1) return the document's root node public Element getRootElement ()

// Document is a Document object Element rootElement = document.getRootElement();(2) return the public java. util. List of all subnodes of the node. GetChildren ()

// The rootElement is an Element object. List bookList = rootElement.getChildren(); (3) return the public java. util. List getAttributes () set of all attribute nodes of the node ()

// Book is an Element object List attrList = book.getAttributes()(4) return the public Element getChild (java. lang. String cname) of the subnode Based on the subnode name)

Element titleElement = book.getChild("title");(5) return the node name public java. lang. String getName ()

// TitleElement is the title node. titleElement.getName();(6) return the node values public java. lang. String getValue (),

titleElement.getValue()The DOM method getNodeValue () returns null for element nodes. Different from DOM, JDOM returns the text value corresponding to the node, whether it is an attribute node or an element node.

Scott MeyersFor this node, DOM getNodeValue () returns null, and JDOM getValue () returns "Scott Meyers ". 1.3 specific instance

package com.qunar.xml;  import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.util.List;  import org.jdom2.Attribute; import org.jdom2.Document; import org.jdom2.Element; import org.jdom2.JDOMException; import org.jdom2.input.SAXBuilder;  /** * Parse XML documents using JDOM * @author sjf0115 * */ public class JDOMXMLCode {  public static void main(String[] args) { try { // Create a SAXBuilder object SAXBuilder saxBuilder = new SAXBuilder(); // Create an input stream object and load the XML document to the input stream FileInputStream inputStream = new FileInputStream("D:\\bookstore.xml"); // Load the input stream to saxBuilder using the build method of the saxBuilder object Document document = saxBuilder.build(inputStream); // Get the root node of the XML document through the document Object Element rootElement = document.getRootElement(); // Obtain the subnode set under the root node based on the Root Node List bookList = rootElement.getChildren(); // Traverse subnodes for (Element book : bookList) { System. out. println ("starting to parse a book ...");  // Parse attributes List attrList = book.getAttributes(); for (Attribute attribute : attrList) { // Attribute name System.out.print("---" + attribute.getName() + "："); // Attribute Value System.out.println(attribute.getValue()); }//for  // Obtain the subnode under the book Node List bookChildren = book.getChildren(); for (Element bookChild : bookChildren) { // Node name System.out.print("------" + bookChild.getName() + "："); // Node Value System.out.println(bookChild.getValue()); }//for  System. out. println ("End parsing a book ..."); }//for } catch (FileNotFoundException e) { e.printStackTrace(); } catch (JDOMException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } } Running result:

Start parsing a book... --- category: Java ------ title: Java multi-thread programming core technology ------ author: Gao Hongyan ------ year: 2015 ------ price: 69.00 end parsing a book... start parsing a book... --- category: C ++ ------ title: Valid tive C ++: 55 Specific Ways to Improve Your Programs and Designs ------ author: Scott Meyers ------ year: 2006 ------ price: 58.00 end parsing a book... start parsing a book... --- category: Web ------ title: Learning XML ------ author: Erik T. ray ------ year: 2016 ------ price: 39.95 end parsing a book...

2. DOM4J parses XML documents2.1 Introduction DOM4J is a Java xml api, similar to JDOM, used to read and write XML files. DOM4J is a very good JavaXML API with excellent performance, powerful functionality, and extremely easy to use features. It is also an open source software that can be found on SourceForge. Now we can see that more and more Java software are using DOM4J to read and write XML. It is particularly worth mentioning that Sun's JAXM is also using DOM4J. This is a required jar package. Hibernate also uses it to read and write configuration files. Jar package: click open link 2.2 to parse (1) create a SAXReader object

SAXReader saxReader = new SAXReader();(2) Use the read method of the SaxReader object to load the XML Document and obtain the Document object.

Document document = saxReader.read(new File("D:\\bookstore.xml"));(3) Get the root node through the Document Object

Element bookstore = document.getRootElement();(4) obtain the iterator through the elementIterator method of the Element Object

Iterator iterator = bookstore.elementIterator();(5) traverse the iterator to get the root node Information

while (iterator.hasNext()) { // Obtain the next subnode Element book = (Element)iterator.next(); }(6) Get the attribute name and attribute value of the attribute node

// Obtain the attribute node set of the book List bookAttr = book.attributes(); // Traverse the book attribute node for (Attribute attribute : bookAttr) { // Obtain the attribute name and attribute value of the property node of the book. System.out.println("name：" + attribute.getName() + " value：" + attribute.getValue()); }//for(7) obtain the node name and the corresponding text value of the element node.

Iterator ite = book.elementIterator(); // Traverse the child nodes of the book Node while(ite.hasNext()){ // Subnode of the book Node Element bookChild = (Element)ite.next(); System.out.println("name：" + bookChild.getName() + " value：" + bookChild.getStringValue()); //System.out.println("name：" + bookChild.getName() + " value：" + bookChild.getText()); }//while2.3 case studies

package com.qunar.xml;  import java.io.File; import java.util.Iterator; import java.util.List;  import org.dom4j.Attribute; import org.dom4j.Document; import org.dom4j.DocumentException; import org.dom4j.Element; import org.dom4j.io.SAXReader;  public class DOM4JXMLCode {  public static void main(String[] args) { try { // Create a SAXReader object SAXReader saxReader = new SAXReader(); // Load the XML Document using the read method of the SaxReader object to obtain the Document Object Document document = saxReader.read(new File("D:\\bookstore.xml")); // Get the root node through the Document Object Element bookstore = document.getRootElement(); // Obtain the iterator through the elementIterator method of the Element Object Iterator iterator = bookstore.elementIterator(); // Traverse the child nodes of the Root Node while (iterator.hasNext()) { System. out. println ("starting to parse a book ..."); // Obtain the next Element Node Element book = (Element)iterator.next(); // Obtain the attribute node set of the book List bookAttr = book.attributes(); // Traverse the book attribute node for (Attribute attribute : bookAttr) { // Obtain the attribute name and attribute value of the property node of the book. System.out.println("name：" + attribute.getName() + " value：" + attribute.getValue()); }//for Iterator ite = book.elementIterator(); // Traverse the child nodes of the book Node while(ite.hasNext()){ // Subnode of the book Node Element bookChild = (Element)ite.next(); System.out.println("name：" + bookChild.getName() + " value：" + bookChild.getStringValue()); //System.out.println("name：" + bookChild.getName() + " value：" + bookChild.getText()); }//while System. out. println ("End parsing a book ..."); } } catch (DocumentException e) { e.printStackTrace(); } } } Running result:

Start parsing a book... name: category value: Javaname: title value: Java multi-thread programming core technology name: author value: Gao Hongyan name: year value: 2015 name: price value: 69.00 end parsing a book... start parsing a book... name: category value: C ++ name: title value: Valid tive C ++: 55 Specific Ways to Improve Your Programs and Designsname: author value: Scott Meyersname: year value: 2006 name: price value: 58.00 end parsing a book... start parsing a book... name: category value: Webname: title value: Learning XMLname: author value: Erik T. rayname: year value: 2016 name: price value: 39.95 end parsing a book...