解析思想:
dom解析
sax解析
基于这两种解析思想市面上就有了很多的解析api
sun jaxp既有dom方式也有sax方式,并且这套解析api已经加入到j2se的规范中,意味这不需要导入任何第三方开发包就可以直接使用这种解析方式.但是这种解析方式效率低下,没什么人用.
dom4j 可以使用dom方式高效的解析xml.
pull
!!dom4j
导入开发包,通常只需要导入核心包就可以了,如果在使用的过程中提示少什么包到lib目录下在导入缺少的包即可
解析的xml文件：
<?xml version="1.0" encoding="UTF-8"?>
<书架>
<书 出版社="北京出版社">
<书名>Java就业培训教程</书名>
<作者>张孝祥</作者>
<售价>50.00元</售价>
<特价>20.0元</特价>
</书>
<书>
<书名>JavaScript网页开发</书名>
<作者>张孝祥</作者>
<售价>40.00元</售价>
</书>
</书架>
SAX解析方式：
package sax;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
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 SaxDemo1 {
public static void main(String[] args) throws Exception {
//解析器工厂
SAXParserFactory factory=SAXParserFactory.newInstance();
//sax解析器
SAXParser parser = factory.newSAXParser();
//获取读取器
XMLReader reader = parser.getXMLReader();
//注册事件
reader.setContentHandler(new MyContentHander2());
//解析xml文档
reader.parse("book.xml");
}
}
//读取第二本书的价格
class MyContentHander2 extends DefaultHandler{
private String eleName="";
private int count=0;
@Override
public void startElement(String uri,String localName,String qName,Attributes attributes) throws SAXException {
super.startElement(uri,localName,qName,attributes);
this.eleName=qName;
}
@Override
public void endElement(String uri,String qName)
throws SAXException {
super.endElement(uri,qName);
eleName="";
}
@Override
public void characters(char[] ch,int start,int length)
throws SAXException {
super.characters(ch,start,length);
if("书名".equals(eleName)&&++count==2){
System.out.println(new String(ch,length));
}
}
}
class MyContentHander implements ContentHandler{
@Override
public void setDocumentLocator(Locator locator) {
// TODO Auto-generated method stub
}
@Override
public void startDocument() throws SAXException {
// TODO Auto-generated method stub
System.out.println("开始读取文档....");
}
@Override
public void endDocument() throws SAXException {
// TODO Auto-generated method stub
System.out.println("结束读取文档....");
}
@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 startElement(String uri,Attributes atts) throws SAXException {
// TODO Auto-generated method stub
System.out.println("发现开始标签,"+qName);
}
@Override
public void endElement(String uri,String qName)
throws SAXException {
// TODO Auto-generated method stub
System.out.println("结束考试标签,"+qName);
}
@Override
public void characters(char[] ch,int length)
throws SAXException {
// TODO Auto-generated method stub
System.out.println(new String(ch,length));
}
@Override
public void ignorableWhitespace(char[] ch,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
}
}
dom4j解析：
package dom4j;
import java.io.FileOutputStream;
import java.util.List;
import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
import org.junit.Test;
public class Dom4jDemo {
@Test
public void attr() throws Exception{
SAXReader reader=new SAXReader();
Document doc = reader.read("book.xml");
Element rootElement = doc.getRootElement();
Element attribute = rootElement.element("书").addAttribute("出版社","北京出版社");
XMLWriter writer = new XMLWriter(new FileOutputStream("book.xml"),OutputFormat.createPrettyPrint());
writer.write(doc);
writer.close();
}
@Test
public void add()throws Exception{
SAXReader reader=new SAXReader();
Document doc = reader.read("book.xml");
Element rootElement = doc.getRootElement();
//凭空创建
Element Telement = DocumentHelper.createElement("特价");
Telement.setText("20.0元");
//挂载
rootElement.element("书").add(Telement);
XMLWriter writer = new XMLWriter(new FileOutputStream("book.xml"),OutputFormat.createPrettyPrint());
writer.write(doc);
writer.close();
}
@Test
public void delete()throws Exception{
SAXReader reader=new SAXReader();
Document doc = reader.read("book.xml");
Element rootElement = doc.getRootElement();
Element element = rootElement.element("书").element("特价");
element.getParent().remove(element);
XMLWriter writer = new XMLWriter(new FileOutputStream("book.xml"),OutputFormat.createPrettyPrint());
writer.write(doc);
writer.close();
}
@Test
public void update() throws Exception{
//dom4j解析器
SAXReader reader=new SAXReader();
//得到document
Document doc = reader.read("book.xml");
//得到根元素
Element rootElement = doc.getRootElement();
List<Element> elements = rootElement.elements();
Element element = elements.get(0);
element.element("售价").setText("50.00元");
XMLWriter writer = new XMLWriter(new FileOutputStream("book.xml"),OutputFormat.createPrettyPrint());
writer.write(doc);
writer.close();
}
@Test
public void find() throws Exception{
//dom4j解析器
SAXReader reader=new SAXReader();
//得到document
Document doc = reader.read("book.xml");
//得到根元素
Element rootElement = doc.getRootElement();
List<Element> elements = rootElement.elements();
Element element = elements.get(1);
System.out.println(element.element("书名").getText());
}
}