Java 解析XML的几种方式：DOM、SAX、JDOM和DOM4J。

　　归纳总结Java解析XML主要有四中方式，分别是DOM、SAX、JDOM和DOM4J。其中DOM和SAX是官方包自带，另外两个JDOM和DOM4J是第三方包。

一、此篇测试代码用到的XML情况 。

1、XML内容展示

<?xml version="1.0" encoding="UTF-8"?>
<class>
    <people>
        <name>Jack</name>
        <age>19</age>
        <sex>male</sex>
        <job>student</job>
    </people>
    <people>
        <name>Merry</name>
        <age>26</age>
        <sex>female</sex>
        <job>teacher</job>
    </people>
</class>

2、所在项目位置

二、几种方式

1、DOM方式

　　代码及运行结果，已省略类名及main函数代码。

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.File;
import java.io.IOException;
/**
 * Create by 摩诘 on 2020/4/5 02:00
 */
        try {
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            String path = HelloWorld.class.getClassLoader().getResource("config/peoples.xml").getPath();
            File file = new File(path);
            Document document = builder.parse(file);
            // 获取节点People集合
            NodeList nodeList = document.getElementsByTagName("people");
            for (int i = 0; i < nodeList.getLength(); i++) {
//                Element element=(Element) nodeList.item(i);
//                NodeList childNodes=element.getChildNodes();
                Node node = nodeList.item(i);
                NodeList childNodes = node.getChildNodes();
                for (int j = 0; j < childNodes.getLength(); j++) {
                    Node childNode = childNodes.item(j);
                    if (childNode.getNodeType() == Node.ELEMENT_NODE) {
                        // 获取节点名称
                        // 获取对应节点包含的值
                        System.out.println(childNode.getNodeName() + ":" + childNode.getFirstChild().getNodeValue());
                    }
                }
                System.out.println("************************");
            }
        } catch (ParserConfigurationException ex) {
            //ex.printStackTrace();
            System.out.println("Error : " + ex.toString());
        } catch (IOException ex) {
            //ex.printStackTrace();
            System.out.println("Error : " + ex.toString());
        } catch (SAXException ex) {
            //ex.printStackTrace();
            System.out.println("Error : " + ex.toString());
        }

2、SAX方式

 　　运行效率和内存使用方面最优的是SAX，但是由于SAX是基于事件的方式，所以SAX无法在编写XML的过程中对已编写内容进行修改，但对于不用进行频繁修改的需求，还是应该选择使用SAX。测试代码主要使用到两个类，一个主函数类HelloWorld，一个SAXHandler继承DefaultHandler并重写方法。

import org.xml.sax.helpers.DefaultHandler;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
/**
 * Create by 摩诘 on 2020/4/5 17:30
 */
public class HelloWorld {
    public static void main(String[] args) throws Exception{
            SAXParserFactory factory=SAXParserFactory.newInstance();
            SAXParser saxParser=factory.newSAXParser();
            DefaultHandler handel=new SAXHandler();
            saxParser.parse("src/config/peoples.xml",handel);
    }
}

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
/**
 * Create by 摩诘 on 2020/4/5 17:30
 */
public class SAXHandler extends DefaultHandler {
    @Override
    public void startDocument() throws SAXException {
        super.startDocument();
        System.out.println("XML解析开始");
    }

    @Override
    public void endDocument() throws SAXException {
        super.endDocument();
        System.out.println("XML解析结束");
    }

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        super.startElement(uri, localName, qName, attributes);
        if(qName.equals("people")){
            System.out.println("*************开始遍历poople*************");
        }else if(!qName.equals("people")&&!qName.equals("class")){
            System.out.println("节点名称："+qName);
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        super.endElement(uri, localName, qName);
        if(qName.equals("people")){
            System.out.println(qName+"遍历结束");
            System.out.println("************结束遍历people**************");
        }
    }

    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        super.characters(ch, start, length);
        String value=new String(ch,start,length).trim();
        if(!value.equals("")){
            System.out.println(value);
        }
    }
}

3、JDOM方式

　　这种方式为三方包，包地址：https://mvnrepository.com/search?q=jdom，通过构建maven项目引用，maven安装与配置：https://blog.csdn.net/github_37759996/article/details/90748461，创建maven Java程序：https://blog.csdn.net/YF_Li123/article/details/79953731?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromBaidu-1&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromBaidu-1，上代码。

import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.input.SAXBuilder;
import org.jdom2.JDOMException;
import java.io.*;
import java.util.List;

/**
 * Create by 摩诘 on 2020/5/2 21:38
 */
public class HelloWorld {
    public static void main(String[] args) {
        SAXBuilder saxBuilder=new SAXBuilder();
        InputStream in;
        try{
            in=new FileInputStream(new File("src\config\peoples.xml"));
            Document document=saxBuilder.build(in);
            Element rootElement=document.getRootElement();
            List<Element> peopleList=rootElement.getChildren();
            for (Element people:peopleList){
                List<Element> childernList=people.getChildren();
                for (Element childern:childernList){
                    System.out.println("2");
                    System.out.println(childern.getName()+":"+childern.getValue());
                }
            }
        }catch(FileNotFoundException e){
            e.printStackTrace();
        }catch(JDOMException e){
            e.printStackTrace();
        }catch(IOException e){
            e.printStackTrace();
        }
    }
}

4、DOM4J

　　三方包，引用方式与JDOM方式类似。看代码

import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import java.io.File;
import java.util.Iterator;
import java.util.List;
/**
 * Create by 摩诘 on 2020/5/2 22:07
 */
public class HelloWorld {
    public static void main(String[] args) {
        SAXReader reader = new SAXReader();
        try{
        Document document = reader.read(new File("src/config/peoples.xml"));
        Element rootElement = document.getRootElement();
        Iterator iterator = rootElement.elementIterator();
        while (iterator.hasNext()){
            Element stu = (Element) iterator.next();
            List<Attribute> attributes = stu.attributes();
            System.out.println("======获取属性值======");
            for (Attribute attribute : attributes) {
                System.out.println(attribute.getValue());
            }
            System.out.println("======遍历子节点======");
            Iterator iterator1 = stu.elementIterator();
            while (iterator1.hasNext()){
                Element stuChild = (Element) iterator1.next();
                System.out.println("节点名："+stuChild.getName()+"---节点值："+stuChild.getStringValue());
            }
         }
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

三、整理参考了以下链接文章

https://www.jb51.net/article/115316.htm

https://blog.csdn.net/m0_37499059/article/details/80505567