XML解析---SAX

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SAX解析

1、编写SaxHelper 继承 DefaultHandler
1）创建目标类
2）创建ArrayList，用来存放解析结果；
3）复写startDocument（）当SAX解析器解析到XML文档开始时，会调用的方法
4）复写endDocument（）当SAX解析器解析到XML文档结束时，会调用的方法
5）复写characters（）当SAX解析器解析到某个元素开始时，会调用的方法其中localName记录的是元素属性名
6）复写endElement（）当SAX解析器解析到某个元素结束时，会调用的方法其中localName记录的是元素属性名

2、编写sax（）
1）创建ArrayList，用来存放解析结果；
2）把xml文件转化为InputSource格式；
3）通过SAXParserFactory.newInstance() 获取factory；
4）通过factory获得saxParser；
5）通过saxParser.getXMLReader() 获得xml阅读器；
6）设置阅读器 handler xmlReader.setContentHandler；
7）设置阅读器的InputSource

## BOOK类 ##

package com.example.xmltest;import java.io.IOException;import java.util.ArrayList;import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.parsers.ParserConfigurationException;import org.w3c.dom.DOMImplementation;import org.w3c.dom.Document;import org.xml.sax.EntityResolver;import org.xml.sax.ErrorHandler;import org.xml.sax.InputSource;import org.xml.sax.SAXExceptionpublic class Book {    private String id;    private String name;    private String prize;    public String getId() {        return id;    }    public void setId(String id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getPrize() {        return prize;    }    public void setPrize(String prize) {        this.prize = prize;    }    public String toString()    {        return this.id + this.name + this.prize ;    }}

待读取xml

<?xml version="1.0" encoding="utf-8"?>  <books>      <book auther="a">          <id>1001</id>          <name>Thinking In Java</name>          <price>80.00</price>      </book>      <book auther="b">          <id>1002</id>          <name>Core Java</name>          <price>90.00</price>      </book>      <book auther="c">          <id>1003</id>          <name>Hello, Andriod</name>          <price>100.00</price>      </book>  </books>

SAXHelper

package com.example.xmltest;import java.util.ArrayList;import java.util.List;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.ext.DefaultHandler2;import org.xml.sax.helpers.DefaultHandler;public class SaxHelper extends DefaultHandler{    private int currentstate = 0;    final int id = 1;    final int name = 2;    final int price = 3;    Book book;    List<Book> books;    public List getbooks()    {        return books;    }    @Override    public void characters(char[] ch, int start, int length)            throws SAXException {        // TODO Auto-generated method stub        String str = new String(ch);        switch (currentstate) {        case id:             book.setId(str);             currentstate = 0;            break;        case name:             book.setName(str);             currentstate = 0;            break;        case price:             book.setPrize(str);             currentstate = 0;            break;        default:            break;        }        super.characters(ch, start, length);    }    @Override    public void endDocument() throws SAXException {        // TODO Auto-generated method stub        super.endDocument();    }    @Override    public void endElement(String uri, String localName, String qName)            throws SAXException {        // TODO Auto-generated method stub        if(localName.equals("book"))        {            books.add(book);        }        super.endElement(uri, localName, qName);    }    @Override    public void startDocument() throws SAXException {        // TODO Auto-generated method stub        books = new ArrayList<Book>();        book = new Book();        super.startDocument();    }    @Override    public void startElement(String uri, String localName, String qName,            Attributes attributes) throws SAXException {        if (localName.equals("books"))        {            currentstate = 0;            return;        }        if (localName.equals("book"))        {            book = new Book();            return;        }        if (localName.equals("id"))        {            currentstate = id;            return;        }        if (localName.equals("name"))        {            currentstate = name;            return;        }        if (localName.equals("price"))        {            currentstate = price;            return;        }        // TODO Auto-generated method stub        super.startElement(uri, localName, qName, attributes);    }}

sax()

private void sax(InputSource inputstream)throws Exception{        SAXParserFactory factory = SAXParserFactory.newInstance();        List<Book> books = new ArrayList<Book>();        try {            SAXParser  saxparser = factory.newSAXParser();            //获得阅读器            XMLReader xmlreader = saxparser.getXMLReader();            SaxHelper saxh =  new SaxHelper();            xmlreader.setContentHandler(saxh);            xmlreader.parse(inputstream);            //返回数据            books = saxh.getbooks();        } catch (ParserConfigurationException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (SAXException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        for(Book book:books)        {            System.out.println(book.toString());        }    }

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