Java 解析 XML

Java 解析 XML 有四种方式

1. DOM(org.w3c.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。

2. SAX(org.xml.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

3. 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

4. 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

示例

books.xml

<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
    <book id="1">
        <name>冰与火之歌</name>
        <author>乔治马丁</author>
        <year>2014</year>
        <price>89</price>
    </book>
    <book id="2">
        <name>安徒生童话</name>
        <author>安徒生</author>
        <year>2004</year>
        <price>77</price>
    </book>
    <book id="3">
        <name>think think think</name>
        <author>aaa</author>
        <year>1997</year>
        <price>100</price>
    </book>
</bookstore>

bean类：Book.java

public class Book {

    /**
     * @author lune
     */

    private int id;
    private String name;
    private String author;
    private int year;
    private double price;

    /**
     * @return the id
     */
    public int getId() {
        return id;
    }
    /**
     * @param id the id to set
     */
    public void setId(int id) {
        this.id = id;
    }
    /**
     * @return the name
     */
    public String getName() {
        return name;
    }
    /**
     * @param name the name to set
     */
    public void setName(String name) {
        this.name = name;
    }
    /**
     * @return the author
     */
    public String getAuthor() {
        return author;
    }
    /**
     * @param author the author to set
     */
    public void setAuthor(String author) {
        this.author = author;
    }
    /**
     * @return the year
     */
    public int getYear() {
        return year;
    }
    /**
     * @param year the year to set
     */
    public void setYear(int year) {
        this.year = year;
    }
    /**
     * @return the price
     */
    public double getPrice() {
        return price;
    }
    /**
     * @param price the price to set
     */
    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "Book [id=" + id + ", name=" + name + ", author=" + author + ", year=" + year + ", price=" + price + "]";
    }

}

1.DOM(org.w3c.dom)方式解析XML

import java.util.ArrayList;
import java.util.List;

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

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

import com.lune.bean.Book;

/**
 * 用DOM方式读取xml文件
 * @author lune
 */
public class ReadxmlByDom {
    private static DocumentBuilderFactory dbFactory = null;
    private static DocumentBuilder db = null;
    private static Document document = null;
    private static List<Book> books = null;
    static{
        try {
            dbFactory = DocumentBuilderFactory.newInstance();
            db = dbFactory.newDocumentBuilder();
        } catch (ParserConfigurationException e) {
            e.printStackTrace();
        }
    }

    public static List<Book> getBooks(String fileName) throws Exception{
        //将给定 URI 的内容解析为一个 XML 文档,并返回Document对象
        document = db.parse(fileName);
        //按文档顺序返回包含在文档中且具有给定标记名称的所有 Element 的 NodeList
        NodeList bookList = document.getElementsByTagName("book");
        books = new ArrayList<Book>();
        //遍历books
        for(int i=0;i<bookList.getLength();i++){
            Book book = new Book();
            //获取第i个book结点
            org.w3c.dom.Node node = bookList.item(i);
            //获取第i个book的所有属性
            NamedNodeMap namedNodeMap = node.getAttributes();
            //获取已知名为id的属性值
            String id = namedNodeMap.getNamedItem("id").getTextContent();//System.out.println(id);
            book.setId(Integer.parseInt(id));

            //获取book结点的子节点,包含了Test类型的换行
            NodeList cList = node.getChildNodes();//System.out.println(cList.getLength());9

            //将一个book里面的属性加入数组
            ArrayList<String> contents = new ArrayList<>();
            for(int j=1;j<cList.getLength();j+=2){

                org.w3c.dom.Node cNode = cList.item(j);
                String content = cNode.getFirstChild().getTextContent();
                contents.add(content);
                //System.out.println(contents);
            }
            
            // 或者直接查找 book 里面的属性
            for(int j=0; j<childNodes.getLength(); j++){
                if(childNodes.item(j).getNodeType() == Node.ELEMENT_NODE){
                    if("name".equals(childNodes.item(j).getNodeName())){
                        System.out.println(childNodes.item(j).getFirstChild().getNodeValue());    
                    }else if("price".equals(childNodes.item(j).getNodeName())){
                        System.out.println(Float.parseFloat(childNodes.item(j).getFirstChild().getNodeValue()));
                    }
                }
            }


            book.setName(contents.get(0));
            book.setAuthor(contents.get(1));
            book.setYear(Integer.parseInt(contents.get(2)));
            book.setPrice(Double.parseDouble(contents.get(3)));
            books.add(book);
        }

        return books;

    }

    public static void main(String args[]){
        String fileName = "src/res/books.xml";
        try {
            List<Book> list = ReadxmlByDom.getBooks(fileName);
            for(Book book :list){
                System.out.println(book);
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

2.SAX(org.xml.sax)方式解析XML

需要自定义DefaultHandler处理器

import java.util.ArrayList;
import java.util.List;

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

import com.lune.bean.Book;

/**
 * 用SAX解析xml文件时需要的handler
 * @author lune
 */
public class SAXParseHandler extends DefaultHandler {
    private List<Book> list;         //存放解析到的book数组
    private Book book;               //存放当前解析的book

    private String content = null;   //存放当前节点值

    /**
     * 开始解析xml文档时调用此方法
     */
    @Override
    public void startDocument() throws SAXException {

        super.startDocument();
        System.out.println("开始解析xml文件");
        list = new ArrayList<Book>();
    }



    /** 
     * 文档解析完成后调用此方法
     */
    @Override
    public void endDocument() throws SAXException {

        super.endDocument();
        System.out.println("xml文件解析完毕");
    }



    /**
     * 开始解析节点时调用此方法
     */
    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {

        super.startElement(uri, localName, qName, attributes);

        //当节点名为book时,获取book的属性id
        if(qName.equals("book")){
            book = new Book();
            String id = attributes.getValue("id");//System.out.println("id值为"+id);
            book.setId(Integer.parseInt(id));
        }

    }


    /**
     *节点解析完毕时调用此方法
     *
     *@param qName 节点名
     */
    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {

        super.endElement(uri, localName, qName);
        if(qName.equals("name")){
            book.setName(content);
            //System.out.println("书名"+content);
        }else if(qName.equals("author")){
            book.setAuthor(content);
        //  System.out.println("作者"+content);
        }else if(qName.equals("year")){
            book.setYear(Integer.parseInt(content));
        //  System.out.println("年份"+content);
        }else if(qName.equals("price")){
            book.setPrice(Double.parseDouble(content));
        //  System.out.println("价格"+content);
        }else if(qName.equals("book")){         //当结束当前book解析时,将该book添加到数组后置为空，方便下一次book赋值
            list.add(book);
            book = null;
        }   

    }



    /** 
     * 此方法用来获取节点的值
     */
    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {

        super.characters(ch, start, length);

        content = new String(ch, start, length);
        //收集不为空白的节点值
//      if(!content.trim().equals("")){
//          System.out.println("节点值为："+content);
//      }

    }

    public List<Book> getBooks(){
        return list;
    }

}

import java.io.IOException;
import java.util.List;

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

import org.xml.sax.SAXException;
import org.xml.sax.helpers.ParserFactory;

import com.lune.bean.Book;
import com.lune.handler.SAXParseHandler;

/**
 * 用SAX方式读取xml文件
 * @author lune
 */
public class ReadXmlBySAX {

    private static List<Book> books = null;

    private  SAXParserFactory sParserFactory = null;
    private  SAXParser parser = null;


    public List<Book> getBooks(String fileName) throws Exception{
        SAXParserFactory sParserFactory = SAXParserFactory.newInstance();
        SAXParser parser = sParserFactory.newSAXParser();

        SAXParseHandler handler = new SAXParseHandler();
        parser.parse(fileName, handler);

        return handler.getBooks();

    }
    /**
     * @param args
     */
    public static void main(String[] args) {
        try {
            books = new ReadXmlBySAX().getBooks("src/res/books.xml");
            for(Book book:books){
                System.out.println(book);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

3.JDOM方式解析XML

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.jdom2.JDOMException;
import org.jdom2.input.SAXBuilder;

import com.lune.bean.Book;

import org.jdom2.*;

/**
 * 用JDOM方式读取xml文件
 * @author lune
 */
public class ReadXMLByJDom {

    private List<Book> books = null;
    private Book book = null;

    public List<Book> getBooks(String fileName){
        SAXBuilder saxBuilder = new SAXBuilder();
        try {
            Document document = saxBuilder.build(new FileInputStream(fileName));
            //获取根节点bookstore
            Element rootElement = document.getRootElement();
            //获取根节点的子节点，返回子节点的数组
            List<Element> bookList = rootElement.getChildren();
            books = new ArrayList<Book>();
            for(Element bookElement : bookList){
                book = new Book();
                //获取bookElement的属性
                List<Attribute> bookAttributes = bookElement.getAttributes();
                for(Attribute attribute : bookAttributes){
                    if(attribute.getName().equals("id")){
                        String id = attribute.getValue(); //System.out.println(id);
                        book.setId(Integer.parseInt(id));
                    }
                }
                //获取bookElement的子节点
                List<Element> children = bookElement.getChildren();
                for(Element child : children){
                    if(child.getName().equals("name")){
                        String name = child.getValue();//System.out.println(name);
                        book.setName(name);
                    }else if(child.getName().equals("author")){
                        String author = child.getValue();
                        book.setAuthor(author);//System.out.println(author);
                    }else if(child.getName().equals("year")){
                        String year = child.getValue();
                        book.setYear(Integer.parseInt(year));
                    }else if(child.getName().equals("price")){
                        String price = child.getValue();
                        book.setPrice(Double.parseDouble(price));
                    }

                }

                books.add(book);
                book = null;

            }

        } catch (FileNotFoundException e) {

            e.printStackTrace();
        } catch (JDOMException e) {

            e.printStackTrace();
        } catch (IOException e) {

            e.printStackTrace();
        }

        return books;

    }


    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String fileName = "src/res/books.xml";
        List<Book> books= new ReadXMLByJDom().getBooks(fileName);
        for(Book book : books){
            System.out.println(book);
        }
    }

}

4.DOM4j方式解析XML

import java.io.File;
import java.util.ArrayList;
import java.util.Iterator;
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;

import com.lune.bean.Book;

/**
 * 用DOM4J方法读取xml文件
 * @author lune
 */
public class ReadXMLByDom4j {

    private List<Book> bookList = null;
    private Book book = null;

    public List<Book> getBooks(File file){

        SAXReader reader = new SAXReader();
        try {
            Document document = reader.read(file);
            Element bookstore = document.getRootElement();
            Iterator storeit = bookstore.elementIterator();

            bookList = new ArrayList<Book>();
            while(storeit.hasNext()){

                book = new Book();
                Element bookElement = (Element) storeit.next();
                //遍历bookElement的属性
                List<Attribute> attributes = bookElement.attributes();
                for(Attribute attribute : attributes){
                    if(attribute.getName().equals("id")){
                        String id = attribute.getValue();//System.out.println(id);
                        book.setId(Integer.parseInt(id));
                    }
                }

                Iterator bookit = bookElement.elementIterator();
                while(bookit.hasNext()){
                    Element child = (Element) bookit.next();
                    String nodeName = child.getName();
                    if(nodeName.equals("name")){
                        //System.out.println(child.getStringValue());
                        String name = child.getStringValue();
                        book.setName(name);
                    }else if(nodeName.equals("author")){
                        String author = child.getStringValue();
                        book.setAuthor(author);
                    }else if(nodeName.equals("year")){
                        String year = child.getStringValue();
                        book.setYear(Integer.parseInt(year));
                    }else if(nodeName.equals("price")){
                        String price = child.getStringValue();
                        book.setPrice(Double.parseDouble(price));
                    }
                }
                bookList.add(book);
                book = null;

            }
        } catch (DocumentException e) {

            e.printStackTrace();
        }


        return bookList;

    }


    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        File file = new File("src/res/books.xml");
        List<Book> bookList = new ReadXMLByDom4j().getBooks(file);
        for(Book book : bookList){
            System.out.println(book);
        }
    }

}

其中后两者需要导入外部jar包.

文章中的源码可在下面地址下载：
http://github.com/clemontine/XMLParser