SAX解析XML文档——（二）

时间：2023-03-09 15:54:14
SAX解析XML文档——（二）

　　SAX从上向下解析，一行一行解析。节省内存，不适合CRUD。

XML文档:

<?xml version="1.0" encoding="UTF-8"?>

<书架>

    <书>

        <书名 name="xxxxx">Java高级</书名>

        <作者>武陟县</作者>

        <价格>200元</价格>

    </书>

    <书>

        <书名>Java中级</书名>

        <作者>打火机</作者>

        <价格>2000元</价格>

    </书>

</书架>

--------------------------------------------解析所有的内容:-----------------

 package XMLParse;

 import javax.xml.parsers.ParserConfigurationException;

 import javax.xml.parsers.SAXParser;

 import javax.xml.parsers.SAXParserFactory;

 import org.apache.commons.lang.Validate;

 import org.xml.sax.Attributes;

 import org.xml.sax.ContentHandler;

 import org.xml.sax.Locator;

 import org.xml.sax.SAXException;

 import org.xml.sax.XMLReader;

 public class Demo1 {

     public static void main(String[] args) throws Exception {

         // 1.创建解析工厂

         SAXParserFactory factory = SAXParserFactory.newInstance();

         // 2.得到解析器

         SAXParser sParser = factory.newSAXParser();

         // 3.得到读取器

         XMLReader reader = sParser.getXMLReader();

         // 4.设置内容处理器

         reader.setContentHandler(new ListHandler());

         // 5.读取xml文件

         reader.parse("src/Book.xml");

     }

 }

 // 得到xml文档的所有内容

 class ListHandler implements ContentHandler {

     // 处理开始标签

     @Override

     public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException {

         System.out.println("<" + qName + ">");

 //        常用的循环方式      读取属性

         for (int i = 0;atts!=null && i < atts.getLength(); i++) {

             String attName = atts.getQName(i);

             String attValue = atts.getValue(i);

             System.out.println(attName+"="+attValue);

         }

     }

     // 处理内容

     @Override

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

         // TODO Auto-generated method stub

         System.out.println(new String(ch, start, length));

     }

     // 处理结束标签

     @Override

     public void endElement(String uri, String localName, String qName) throws SAXException {

         System.out.println("</" + qName + ">");

     }

     @Override

     public void setDocumentLocator(Locator locator) {

         // TODO Auto-generated method stub

     }

     @Override

     public void startDocument() throws SAXException {

         // TODO Auto-generated method stub

     }

     @Override

     public void endDocument() throws SAXException {

         // TODO Auto-generated method stub

     }

     @Override

     public void startPrefixMapping(String prefix, String uri) throws SAXException {

         // TODO Auto-generated method stub

     }

     @Override

     public void endPrefixMapping(String prefix) throws SAXException {

         // TODO Auto-generated method stub

     }

     @Override

     public void ignorableWhitespace(char[] ch, int start, int length) throws SAXException {

         // TODO Auto-generated method stub

     }

     @Override

     public void processingInstruction(String target, String data) throws SAXException {

         // TODO Auto-generated method stub

     }

     @Override

     public void skippedEntity(String name) throws SAXException {

         // TODO Auto-generated method stub

     }

 }

结果:

<书架>

<书>

<书名>

name=xxxxx

Java高级

</书名>

<作者>

武陟县

</作者>

<价格>

200元

</价格>

</书>

<书>

<书名>

Java中级

</书名>

<作者>

打火机

</作者>

<价格>

2000元

</价格>

</书>

</书架>

 -----------------------------------------解析指定的标签------------------------------------------------------

 package XMLParse;

 import javax.xml.parsers.ParserConfigurationException;

 import javax.xml.parsers.SAXParser;

 import javax.xml.parsers.SAXParserFactory;

 import org.apache.commons.lang.Validate;

 import org.xml.sax.Attributes;

 import org.xml.sax.ContentHandler;

 import org.xml.sax.Locator;

 import org.xml.sax.SAXException;

 import org.xml.sax.XMLReader;

 import org.xml.sax.helpers.DefaultHandler;

 public class Demo3 {

     public static void main(String[] args) throws Exception {

         // 1.创建解析工厂

         SAXParserFactory factory = SAXParserFactory.newInstance();

         // 2.得到解析器

         SAXParser sParser = factory.newSAXParser();

         // 3.得到读取器

         XMLReader reader = sParser.getXMLReader();

         // 4.设置内容处理器

         reader.setContentHandler(new TagValueHandler_1());

         // 5.读取xml文件

         reader.parse("src/Book.xml");

     }

 }

 //读取指定的标签（读取书名）

 class TagValueHandler_1 extends DefaultHandler{

     private String currentTag;  //记住当前的标签是那个

     private int needNum = 2;    //记住需要第几个

     private int currentNum;     //记住当前是第几个

     @Override

     public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {

         if("书名".equals(qName)){

             currentTag="书名";

             currentNum++;

         }

     }

     @Override

     public void endElement(String uri, String localName, String qName) throws SAXException {

         currentTag=null;

     }

     @Override

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

         if("书名".equals(currentTag)&&needNum==currentNum){

             System.out.println(new String(ch,start,length));

         }

     }

 }

结果:

Java中级

-------------------------------------解析后封装到对象------------------------------

package XMLParse;

import java.util.ArrayList;

import java.util.List;

import javax.xml.parsers.ParserConfigurationException;

import javax.xml.parsers.SAXParser;

import javax.xml.parsers.SAXParserFactory;

import org.apache.commons.lang.Validate;

import org.xml.sax.Attributes;

import org.xml.sax.ContentHandler;

import org.xml.sax.Locator;

import org.xml.sax.SAXException;

import org.xml.sax.XMLReader;

import org.xml.sax.helpers.DefaultHandler;

public class Demo4 {

    public static void main(String[] args) throws Exception {

        // 1.创建解析工厂

        SAXParserFactory factory = SAXParserFactory.newInstance();

        // 2.得到解析器

        SAXParser sParser = factory.newSAXParser();

        // 3.得到读取器

        XMLReader reader = sParser.getXMLReader();

        // 4.设置内容处理器

        ListBeanHandler listBeanHandler = new ListBeanHandler();

        reader.setContentHandler(listBeanHandler);

        // 5.读取xml文件

        reader.parse("src/Book.xml");

        List<Book> list = listBeanHandler.getList();

        System.out.println(list);

    }

}

// 读取指定的标签（读取书名）

class ListBeanHandler extends DefaultHandler {

    private String currentTag; // 记住当前的标签是那个

    private List<Book> list = new ArrayList<Book>();

    private Book book;

    @Override

    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {

        currentTag = qName;

        if ("书".equals(qName)) {

            book = new Book();

        }

    }

    @Override

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

        if("书名".equals(currentTag)){

            book.setName(new String(ch, start, length));

        }

        if("作者".equals(currentTag)){

            book.setAuthor(new String(ch, start, length));

        }

        if("价格".equals(currentTag)){

            book.setPrice(new String(ch, start, length));

        }

    }

    @Override

    public void endElement(String uri, String localName, String qName) throws SAXException {

        currentTag = null;

        if("书".equals(qName)){

            list.add(book);

            book=null;

        }

    }

    public List<Book> getList() {

        return list;

    }

    public void setList(List<Book> list) {

        this.list = list;

    }

}

结果:

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