XML的四种解析方式

第一类：JAXP  － java api for xml process

            1.Dom

                 2.sax

                  3.StAx

第二种：第三方框架

                  Dom4j

 

 

Jaxp中所有解析方式的主要解析类，都是通过工厂模式获取到的。

 

第一种：jaxp-dom

    @Test

    public void jaxpDom() throws Exception{

       DocumentBuilder db=DocumentBuilderFactory.newInstance()

                       .newDocumentBuilder();

       Document dom = db.parse (DomDemo.class.getClassLoader()

                         .getResourceAsStream("users.xml"));

       NodeList nl = dom.getElementsByTagName("user");

       int len = nl.getLength();

       for(int i=0;i<len;i++){

           Element el = (Element) nl.item(i);

           String id = el.getAttribute("id");

           String name = el.getElementsByTagName("name")

                            .item(0).getTextContent();

           String age = el.getElementsByTagName("age")

                            .item(0).getTextContent();

           System.err.println("id:"+id+","+name+","+age);

       }

    }

 

第二步：jaxp-sax

<wj:web-app version="2.5"

    xmlns:wj[W1] ="http://java.sun.com/xml/ns/javaee"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

  <wj:display-name></wj:display-name> 

 

  <wj:filter>[W2] 

    <wj:filter-name></wj:filter-name>

    <wj:filter-class></wj:filter-class>

  </wj:filter[W3] >

 

    @Test

    public void jaxpSax() throws Exception{

       SAXParser sax = SAXParserFactory.newInstance().newSAXParser();

       sax.parse(in,new DefaultHandler(){

           private boolean nameOrAge=false;

           /**

            * 某个元素开始了<somename>

            */

           @Override

           public void startElement(String uri, String localName,

                  String qName, Attributes attr) throws SAXException {

              if(qName.equals("user")){

                  System.err.println(attr.getValue("id"));

              }else if(qName.equals("name") || qName.equals("age")){

                  nameOrAge=true;

              }

           }

           /**

            * 某个元素的结束</somename>

            */

           @Override

           public void endElement(String uri, String localName, String qName)

                  throws SAXException {

              if(qName.equals("name") || qName.equals("age")){

                  nameOrAge=false;

              }

           }

           /**

            * 字符的开始<>someValue</>

            */

           @Override

           public void characters(char[] ch, int start, int length)

                  throws SAXException {

              if(nameOrAge){

                  String value = new String(ch,start,length);

                  System.err.println(value);

              }

           }

       });

    }

 

 

第三步：jaxp-StAX

    /**

     * pull解析

     * javax.xml.stream

     */

    @Test

    public void jaxpStax() throws Exception{

       XMLStreamReader xml =

              XMLInputFactory.newInstance().createXMLStreamReader(in);

       int tag = xml.next();[W4] 

       while(tag!=XMLStreamReader.END_DOCUMENT[W5] ){

           if(tag==XMLStreamReader.START_ELEMENT[W6] ){

              if(xml.getLocalName().equals("user")[W7] ){

                  String id = xml.getAttributeValue(0);

                  System.err.println(id);

              }

              if(xml.getLocalName().equals("name")){

                  String name = xml.getElementText();

                  System.err.println("name:"+name);

              }

              if(xml.getLocalName().equals("age")){

                  String age = xml.getElementText();

                  System.err.println("age:"+age);

              }

           }

           tag = xml.next();

       }

    }

 

 

第四种：dom4j

 

代码：

    @Test

    public void testDom4j() throws Exception{

       SAXReader reader = new SAXReader();

       org.dom4j.Document dom = reader.read(in);

       List<org.dom4j.Element> list= dom.selectNodes("//user");

       for(org.dom4j.Element el:list){

           String id=el.attributeValue("id");

           String name = el.elementText("name");

           String age = el.element("age").getText();

           System.err.println(id+","+name+","+age);

       }

    }