java--xml文件读取(SAX)

package com.imooc_xml.sax.handler;

import java.util.ArrayList;

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

import com.imooc_xml.sax.entity.Book;

public class SAXParserHandler extends DefaultHandler {

    //使用全局变量可以使本类的各个方法通用，联系
    int bookIndex = 0 ;
    String value = null;
    Book book = null;
    private ArrayList<Book> bookList = new ArrayList<Book>();
    public ArrayList<Book> getBookList() {
        return bookList;
    }
    /**
     * 用来遍历xml文件的开始标签
     */
    @Override
    public void startElement(String uri, String localName, String qName,
            Attributes attributes) throws SAXException {
        // TODO Auto-generated method stub
        super.startElement(uri, localName, qName, attributes);
        ////解析xml文件的节点属性,只有book节点有属性
        if(qName.equals("book")){
            book = new Book();
            bookIndex++;
            //已知book的属性名
//            attributes.getValue("id");
            //不知book元素的属性名和个数
            int num = attributes.getLength();
            for(int i=0;i<num;i++){
                //book元素的第i+1个属性名
                attributes.getQName(i);
                attributes.getValue(i);
                if(attributes.getQName(i).equals("id")){
                    book.setId(attributes.getValue(i));
                }
            }
        }else if (!qName.equals("book")&&!qName.equals("bookstore")){
            //节点名
            System.out.println(qName);
        }
    }
    /**
     * 用来遍历xml文件的结束标签
     */
    @Override
    public void endElement(String uri, String localName, String qName)
            throws SAXException {
        // TODO Auto-generated method stub
        super.endElement(uri, localName, qName);
        //判断是否针对一本书已经遍历结束
        if (qName.equals("book")){
            bookList.add(book);
            book = null;
            System.out.println("结束遍历第"+bookIndex+"本书");
        }else if(qName.equals("name")){
            book.setName(value);
        }else if(qName.equals("author")){
            book.setAuthor(value);
        }else if(qName.equals("year")){
            book.setYear(value);
        }else if(qName.equals("price")){
            book.setPrice(value);
        }else if(qName.equals("language")){
            book.setLanguage(value);
        }
        
    }
    @Override
    public void characters(char[] ch, int start, int length)
            throws SAXException {
        // TODO Auto-generated method stub
        super.characters(ch, start, length);
        //ch是节点之间的文本内容
        value = new String(ch, start, length);
        //判断空格和换行
        if(!value.trim().equals("")){
            System.out.println(value);
        }
    }
    /**
     * 用来标志解析开始
     */
    @Override
    public void startDocument() throws SAXException {
        // TODO Auto-generated method stub
        super.startDocument();
        System.out.println("SAX解析开始");
    }
    /**
     * 用来标志解析结束
     */
    @Override
    public void endDocument() throws SAXException {
        // TODO Auto-generated method stub
        super.endDocument();
        System.out.println("SAX解析结束");
    }
}

package com.imooc_xml.sax.test;

import java.io.IOException;

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

import org.xml.sax.SAXException;

import com.imooc_xml.sax.handler.SAXParserHandler;

public class SAXTest {

    public static void main(String[] args) {

        //通过SAXParserFactory的静态newInstance()方法获取SAXParserFactory的实例factory
        SAXParserFactory factory = SAXParserFactory.newInstance();
        
        try {
            //通过factory获取SAXParser实例
            SAXParser parser = factory.newSAXParser();
            //创建一个handler对象
            SAXParserHandler handler = new SAXParserHandler();
            parser.parse("xml/books.xml", handler);
        } catch (ParserConfigurationException | SAXException e) {
            e.printStackTrace();
        }catch (IOException e) {
            e.printStackTrace();
        }
    }
}

//只有book节点有属性
        if(qName.equals("book")){
            //已知book的属性名
//            attributes.getValue("id");
            //不知book元素的属性名和个数‘
            int num = attributes.getLength();
            for(int i=0;i<num;i++){
                //book元素的第i+1个属性名
                attributes.getQName(i);
                attributes.getValue(i);
            }
        }

 @Override
    public void characters(char[] ch, int start, int length)
            throws SAXException {
        // TODO Auto-generated method stub
        super.characters(ch, start, length);
        //ch是节点之间的文本内容
        value = new String(ch, start, length);
        //判断空格和换行
        if(!value.trim().equals("")){
            System.out.println(value);
        }
    }

public class Book {
    
    private String id;
    private String name;
    private String author;
    private String year;
    private String price;
    private String language;

handler.getBookList().size();
            for(Book book:handler.getBookList()){
                System.out.println(book.getId());
　　　　　　　　　 ....
            }