Dom4j遍历和更新XML

一、Dom4j

1、DOM文档对象模型

DOM（Document Object Model）定义了访问和操作XML文档的标准方法，DOM把XML文档作为树结构来查看，能够通过DOM树来读写所有元素。

2、Dom4j

Dom4j是一个易用的、开源的库，用于解析XML，它用于Java平台。

Dom4j将XML视为Document对象。

XML标签被Dom4j定义为Element对象。

二、Dom4j遍历XML

xml页面

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hr SYSTEM "hr.dtd">
<!-- 人力资源管理系统 -->
<hr>
	<employee no="3309">
		<name>张三</name>
		<age>31</age>
		<salary>5000</salary>
		<department>
			<dname>行政部</dname>
			<address>xx大厦-B103</address>
		</department>
	</employee>
	
	<employee no="3310">
		<name>李四</name>
		<age>29</age>
		<salary>8000</salary>
		<department>
			<dname>技术部</dname>
			<address>xx大厦-B104</address>
		</department>
	</employee>
	
</hr>

java页面

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类是读取XML文件的核心类，用于将XML解析以“树”的形式保存
		SAXReader reader = new SAXReader();
		try {
    
			Document document = reader.read(file);
			// 获取XML文档的根节点，即hr标签
			Element root = document.getRootElement();
			// elements方法用于获取指定的标签合集
			List<Element> employees = root.elements("employee");   
			for(Element employee : employees) {
    
				// element方法用于获取唯一的子节点对象
				Element name = employee.element("name");
				String empName = name.getText();// getText()方法用于获取标签文本
				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();
	}
}

输出页面

三、Dom4j更新XML

java页面

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("王五");
			employee.addElement("age").setText("24");
			employee.addElement("salary").setText("3600");
			Element department = employee.addElement("department");
			department.addElement("dname").setText("人事部");
			department.addElement("address").setText("XX大厦-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页面改变

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hr SYSTEM "hr.dtd"><!-- 人力资源管理系统 -->
<hr>
	<employee no="3309">
		<name>张三</name>
		<age>31</age>
		<salary>5000</salary>
		<department>
			<dname>行政部</dname>
			<address>xx大厦-B103</address>
		</department>
	</employee>

	<employee no="3310">
		<name>李四</name>
		<age>29</age>
		<salary>8000</salary>
		<department>
			<dname>技术部</dname>
			<address>xx大厦-B104</address>
		</department>
	</employee>

	<employee no="3311">
		<name>王五</name>
		<age>24</age>
		<salary>3600</salary>
		<department>
			<dname>人事部</dname>
			<address>XX大厦-B205</address>
		</department>
	</employee>
</hr>