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sax

原理 一个元素一个元素解析 解析到一个元素调用相关的方法 startDocument() 文档开始 endDocument 文档结束 startElement 元素开始 endElement元素结束 characters 文本内容

@Test

public void saxParser() throws Exception{

//获取工厂

SAXParserFactory parserFactory = SAXParserFactory.newInstance();

SAXParser saxParser = parserFactory.newSAXParser();

//获取xmlReader通过这个reader可以试着 ContentHandler

XMLReader xmlReader = saxParser.getXMLReader();

//给xmlReader设置contentHandler contentHandler是一个接口 里面太多的方法没实现

//不去直接实现contenthandler 而是继承它默认的实现 DefaultHandler

xmlReader.setContentHandler(new Myhandler());

//解析xml文档

xmlReader.parse("book.xml");

}

private class Myhandler extends DefaultHandler{

@Override

public void startDocument() throws SAXException {

System.out.println("文档开始");

}

@Override

public void endDocument() throws SAXException {

System.out.println("文档结束");

}

@Override

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

throws SAXException {

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

}

@Override

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

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

}

@Override

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

//文本内容

String text = new String(ch,start,length);

System.out.println("文本内容"+text);

}

}

 

读出某一个元素对应的内容

@Test

public void saxParserTest2() throws Exception{

SAXParserFactory parserFactory = SAXParserFactory.newInstance();

SAXParser parser = parserFactory.newSAXParser();

XMLReader reader = parser.getXMLReader();

reader.setContentHandler(new DefaultHandler(){

boolean isPrice = false;

int count = 0;

@Override

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

throws SAXException {

if("售价".equals(qName)){

isPrice = true;

count++;

}

}

@Override

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

if("售价".equals(qName)){

isPrice = false;

}

}

@Override

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

if(isPrice && count == 2){

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

}

}

});

reader.parse("book.xml");

}

 

解析成arraylist

@Test

public void saxParse2list() throws Exception{

SAXParserFactory parserFactory = SAXParserFactory.newInstance();

SAXParser parser = parserFactory.newSAXParser();

XMLReader reader = parser.getXMLReader();

reader.setContentHandler(new DefaultHandler(){

ArrayList<Book> bookshelf = null;

Book book = null;

String tag = null;

@Override

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

throws SAXException {

if("书架".equals(qName)){

//创建集合

bookshelf = new ArrayList<Book>();

}else if("书".equals(qName)){

//创建book对象

book = new Book();

}else if("书名".equals(qName)){

tag = "书名";

}else if("作者".equals(qName)){

tag = "作者";

}else if("售价".equals(qName)){

tag = "售价";

}

}

@Override

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

//每次走到结束标签 都要把tag复原为null

tag = null;

if("书架".equals(qName)){

for(Book book1:bookshelf){

System.out.println(book1);

}

}else if("书".equals(qName)){

//读到书的结束标签 把book对象添加到集合中

bookshelf.add(book);

}

}

@Override

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

if("书名".equals(tag)){

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

}else if("作者".equals(tag)){

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

}else if("售价".equals(tag)){

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

}

}

});

reader.parse("book.xml");

}