XML---解析

本文介绍三种xml文件的解析方法，Dom解析，SAX解析，Dom4j解析。
1.Dom解析
Dom解析是javax下的一种xml解析方法
解析过程如下：

package parseXML;


import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class DomTest {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
            try {
                readXml("src/basic/basic.xml");
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
    }
    public static void readXml(String path) throws Exception{
        //1.拿到工厂
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        //2.拿到解析器
        DocumentBuilder builder =factory.newDocumentBuilder();
        //3.解析XML
        Document doc=builder.parse(path);
        //4.拿到根标签
        Element root=doc.getDocumentElement();
        //查看所有节点内容
        showDetail(root);
    }
    public static void showDetail(Node node){
        //1.查看本节点内容
        String name =node.getNodeName();
        if("#text".equals(name)){
            name = node.getTextContent();
        }
        System.out.print(name);
        //2.本节点属性
        NamedNodeMap attrs=node.getAttributes();
        if(attrs!=null){
            int len = attrs.getLength();
            for(int i=0;i<len;i++){
                Node att =attrs.item(i);
                String key =att.getNodeName();
                String value =att.getNodeValue();
                System.out.print("  "+key+" ="+value+"    ");
            }
        }
        System.out.println();
        //递归
        //node.getChildNodes().getLength()>0
        //node.hasChildNodes()
        if(node.hasChildNodes()){
            NodeList cns=node.getChildNodes();
            int len=cns.getLength();
            for(int i = 0; i < len; i++){
                Node cn =cns.item(i);
                showDetail(cn);
            }
        }
    }
}

2.SAX解析
SAX解析也是由javax提供的xml文件的解析方法
解析过程如下：

package parseXML;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class SAXTest {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
         try {
            readXml("src/basic/basic.xml");
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public static void readXml(String path)throws Exception{
        SAXParserFactory factory =SAXParserFactory.newInstance();
        SAXParser  parser =factory.newSAXParser();
        parser.parse(path, 
                new DefaultHandler(){

                    @Override
                    public void startDocument() throws SAXException {
                        System.out.println("开始读取xml文档");

                    }

                    @Override
                    public void endDocument() throws SAXException {
                        System.out.println("xml读取结束");

                    }

                    @Override
                    public void startElement(String uri, String localName, String qName, Attributes attributes)
                            throws SAXException {
                        System.out.print("<"+qName);
                        int len =attributes.getLength();
                        for(int i =0;i<len ;i++){
                            String key =attributes.getQName(i);
                            String value =attributes.getValue(i);
                            System.out.print(key+"= "+value+"  ");
                        }
                        System.out.print(">");
                        System.out.println();
                    }

                    @Override
                    public void endElement(String uri, String localName, String qName) throws SAXException {
                        System.out.println("</"+qName+">");
                    }

                    @Override
                    public void characters(char[] ch, int start, int length) throws SAXException {
                        System.out.println("字符内容："+new String(ch, start, length));
                    }

                       }
                );
    }
}

3.Dom4解析方法
Dom4解析方法需要添加dom4j架包。
解析过程如下：

package parseXML;

import java.util.List;

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


public class Dome4Test {

    public static void main(String[] args) {
        try {
            readXml("src/basic/basic.xml");
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public static void readXml(String path)throws Exception{
        SAXReader reader =new SAXReader();
        Document doc=reader.read(path);
        Element root =doc.getRootElement();
        showDetail(root);
    }
    private static void showDetail(Element e) {
        //查看节点内容
        String name =e.getName();
        String text =e.getText();
        System.out.print(name);
        List<Attribute> attrs =e.attributes();
        //展示属性
        if(attrs!=null){
            for(Attribute attr:attrs){
                String key=attr.getName();
                String value =attr.getValue();
                System.out.print(" "+key+"="+value+" ");
            }
        }
        if(text!=null){
            System.out.print(text);
        }
        System.out.println();
        //判断是否有子节点
        if(e.hasContent()){
            List<Element> elements=e.elements();
            for(Element ele:elements){
                showDetail(ele);
            }
        }
    }
}