java如何解析XML

DOM方式解析XML

Dom解析是将xml文件全部载入到内存，组装成一颗dom树，然后通过节点以及节点之间的关系来解析xml文件,与平台无关,java提供的一种基础的解析XML文件的API,理解较简单，但是由于整个文档都需要载入内存,不适用于文档较大时。 （推荐学习：java课程）

SAX方式解析XML

基于事件驱动,逐条解析,适用于只处理xml数据，不易编码,而且很难同时访问同一个文档中的多处不同数据

JDOM方式解析XML

简化与XML的交互并且比使用DOM实现更快,仅使用具体类而不使用接口因此简化了API,并且易于使用

DOM4j方式解析XML

JDOM的一种智能分支,功能较强大，建议熟练使用

xml文件

<?xml version="1.0" encoding="utf-8" ?><class>    <student>        <firstname>cxx1</firstname>        <lastname>Bob1</lastname>        <nickname>stars1</nickname>        <marks>85</marks>    </student>    <student rollno="493">        <firstname>cxx2</firstname>        <lastname>Bob2</lastname>        <nickname>stars2</nickname>        <marks>85</marks>    </student>    <student rollno="593">        <firstname>cxx3</firstname>        <lastname>Bob3</lastname>        <nickname>stars3</nickname>        <marks>85</marks>    </student></class>

DOM方式

package com.cxx.xml;import org.w3c.dom.*;import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;/** * @Author: cxx * Dom操作xml * @Date: 2018/5/29 20:19 */public class DomDemo {    //用Element方式    public static void element(NodeList list){        for (int i = 0; i <list.getLength() ; i++) {            Element element = (Element) list.item(i);            NodeList childNodes = element.getChildNodes();            for (int j = 0; j <childNodes.getLength() ; j++) {                if (childNodes.item(j).getNodeType()==Node.ELEMENT_NODE) {                    //获取节点                    System.out.print(childNodes.item(j).getNodeName() + ":");                    //获取节点值                    System.out.println(childNodes.item(j).getFirstChild().getNodeValue());                }            }        }    }    public static void node(NodeList list){        for (int i = 0; i <list.getLength() ; i++) {            Node node = list.item(i);            NodeList childNodes = node.getChildNodes();            for (int j = 0; j <childNodes.getLength() ; j++) {                if (childNodes.item(j).getNodeType()==Node.ELEMENT_NODE) {                    System.out.print(childNodes.item(j).getNodeName() + ":");                    System.out.println(childNodes.item(j).getFirstChild().getNodeValue());                }            }        }    }    public static void main(String[] args) {        //1.创建DocumentBuilderFactory对象        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();        //2.创建DocumentBuilder对象        try {            DocumentBuilder builder = factory.newDocumentBuilder();            Document d = builder.parse("src/main/resources/demo.xml");            NodeList sList = d.getElementsByTagName("student");            //element(sList);            node(sList);        } catch (Exception e) {            e.printStackTrace();        }    }}

SAX方式

package com.cxx.xml;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.helpers.DefaultHandler;import javax.xml.parsers.SAXParser;import javax.xml.parsers.SAXParserFactory;/** * @Author: cxx * SAX解析DOM * 一行一行  Handler * startElement * endElement * @Date: 2018/5/29 20:03 */public class SaxDemo {    public static void main(String[] args) throws Exception {        //1.或去SAXParserFactory实例        SAXParserFactory factory = SAXParserFactory.newInstance();        //2.获取SAXparser实例        SAXParser saxParser = factory.newSAXParser();        //创建Handel对象        SAXDemoHandel handel = new SAXDemoHandel();        saxParser.parse("src/main/resources/demo.xml",handel);    }}class SAXDemoHandel extends DefaultHandler {    //遍历xml文件开始标签    @Override    public void startDocument() throws SAXException {        super.startDocument();        System.out.println("sax解析开始");    }    //遍历xml文件结束标签    @Override    public void endDocument() throws SAXException {        super.endDocument();        System.out.println("sax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("student")){            System.out.println("============开始遍历student=============");            //System.out.println(attributes.getValue("rollno"));        }        else if (!qName.equals("student")&&!qName.equals("class")){            System.out.print("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("student")){            System.out.println(qName+"遍历结束");            System.out.println("============结束遍历student=============");        }    }    @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);        }    }}

JDOM方式

<!--jdom --><dependency>    <groupId>org.jdom</groupId>    <artifactId>jdom</artifactId>    <version>1.1.3</version></dependency>

package com.cxx.xml;import org.jdom.Attribute;import org.jdom.Document;import org.jdom.Element;import org.jdom.input.SAXBuilder;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.InputStream;import java.util.List;/** * @Author: cxx * JDom解析xml * 快速开发XML应用程序。 * 是一个开源项目 * JDOM主要用来弥补DOM和SAX在实际应用当中的不足。 * @Date: 2018/5/30 11:44 */public class JDomDemo {    public static void main(String[] args) throws Exception {        //1.创建SAXBuilder对象        SAXBuilder saxBuilder = new SAXBuilder();        //2.创建输入流        InputStream is = new FileInputStream(new File("src/main/resources/demo.xml"));        //3.将输入流加载到build中        Document document = saxBuilder.build(is);        //4.获取根节点        Element rootElement = document.getRootElement();        //5.获取子节点        List<Element> children = rootElement.getChildren();        for (Element child : children) {            System.out.println("通过rollno获取属性值:"+child.getAttribute("rollno"));            List<Attribute> attributes = child.getAttributes();            //打印属性            for (Attribute attr : attributes) {                System.out.println(attr.getName()+":"+attr.getValue());            }            List<Element> childrenList = child.getChildren();            System.out.println("======获取子节点-start======");            for (Element o : childrenList) {                System.out.println("节点名:"+o.getName()+"---"+"节点值:"+o.getValue());            }            System.out.println("======获取子节点-end======");        }    }}

DOM4J方式

 <!-- dom4j --> <dependency>     <groupId>dom4j</groupId>     <artifactId>dom4j</artifactId>     <version>1.6.1</version></dependency>

package com.cxx.xml;import org.dom4j.Attribute;import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.Element;import org.dom4j.io.SAXReader;import java.io.File;import java.util.Iterator;import java.util.List;/** * @Author: cxx * Dom4j解析xml * @Date: 2018/5/30 12:21 */public class Dom4JDemo {    public static void main(String[] args) throws Exception {        //1.创建Reader对象        SAXReader reader = new SAXReader();        //2.加载xml        Document document = reader.read(new File("src/main/resources/demo.xml"));        //3.获取根节点        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());            }        }    }}