Dom4j traverses and updates XML

One 、Dom4j

1、DOM Document object model

DOM（Document Object Model） Defines access and operations XML Standard approach to documentation ,DOM hold XML The document is viewed as a tree structure , Can pass DOM Tree to read and write all elements .

2、Dom4j

Dom4j It's an easy to use 、 Open source library , For parsing XML, It is used for Java platform .

Dom4j take XML As Document object .

XML The label is Dom4j Defined as Element object .

Two 、Dom4j Traverse XML

xml page

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hr SYSTEM "hr.dtd">
<!--  Human resource management system  -->
<hr>
	<employee no="3309">
		<name> Zhang San </name>
		<age>31</age>
		<salary>5000</salary>
		<department>
			<dname> The administration department </dname>
			<address>xx building -B103</address>
		</department>
	</employee>
	
	<employee no="3310">
		<name> Li Si </name>
		<age>29</age>
		<salary>8000</salary>
		<department>
			<dname> Technology Department </dname>
			<address>xx building -B104</address>
		</department>
	</employee>
	
</hr>

java page

package com.imooc.dom4j;

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 HrReader{
    
	public void readXml() {
    
		String file="d:/workplace/xml/src/hr.xml";
		// SAXReader Class is read XML Core classes of files , Is used to XML Resolve to “ Trees ” Form preservation of 
		SAXReader reader = new SAXReader();
		try {
    
			Document document = reader.read(file);
			//  obtain XML The root node of the document , namely hr label 
			Element root = document.getRootElement();
			// elements Method is used to get the specified set of tags 
			List<Element> employees = root.elements("employee");   
			for(Element employee : employees) {
    
				// element Method is used to get the unique child node object 
				Element name = employee.element("name");
				String empName = name.getText();// getText() Method is used to get the label text 
				System.out.println(empName);
				System.out.println(employee.elementText("age"));
				System.out.println(employee.elementText("salary"));
				Element department = employee.element("department");
				System.out.println(department.element("dname").getText());
				System.out.println(department.element("address").getText());
				Attribute att = employee.attribute("no");
				System.out.println(att.getText()+"\n");
			}
		} catch (DocumentException e) {
    
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public static void main(String[] args) {
    
		HrReader reader = new HrReader();
		reader.readXml();
	}
}

Output page

3、 ... and 、Dom4j to update XML

java page

package com.imooc.dom4j;


import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class HrWriter {
    
	public void writeXml() {
    
		String file = "d:/workplace/xml/src/hr.xml";
		SAXReader reader = new SAXReader();
		try {
    
			Document document = reader.read(file);
			Element root = document.getRootElement();
			Element employee = root.addElement("employee");
			employee.addAttribute("no","3311");
			Element name = employee.addElement("name");
			name.setText(" Wang Wu ");
			employee.addElement("age").setText("24");
			employee.addElement("salary").setText("3600");
			Element department = employee.addElement("department");
			department.addElement("dname").setText(" The personnel department ");
			department.addElement("address").setText("XX building -B205");
			Writer writer = new OutputStreamWriter(new FileOutputStream(file),"UTF-8");
			document.write(writer);
			writer.close();
		} catch (Exception e) {
    
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public static void main(String[] args) {
    
		HrWriter hrWriter = new HrWriter();
		hrWriter.writeXml();
	}
}

xml Change the page

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hr SYSTEM "hr.dtd"><!--  Human resource management system  -->
<hr>
	<employee no="3309">
		<name> Zhang San </name>
		<age>31</age>
		<salary>5000</salary>
		<department>
			<dname> The administration department </dname>
			<address>xx building -B103</address>
		</department>
	</employee>

	<employee no="3310">
		<name> Li Si </name>
		<age>29</age>
		<salary>8000</salary>
		<department>
			<dname> Technology Department </dname>
			<address>xx building -B104</address>
		</department>
	</employee>

	<employee no="3311">
		<name> Wang Wu </name>
		<age>24</age>
		<salary>3600</salary>
		<department>
			<dname> The personnel department </dname>
			<address>XX building -B205</address>
		</department>
	</employee>
</hr>