零教程

演示示例

这是输入需要解析xml文件：

<?xml version="1.0"?>
<class>
   <student rollno="393">
      <firstname>dinkar</firstname>
      <lastname>kad</lastname>
      <nickname>dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno="493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno="593">
      <firstname>jasvir</firstname>
      <lastname>singn</lastname>
      <nickname>jazz</nickname>
      <marks>90</marks>
   </student>
</class>

%uA0

StAXParserDemo.java

package com.yiibai.xml

import java.io.FileNotFoundException
import java.io.FileReader
import java.util.Iterator

import javax.xml.stream.XMLEventReader
import javax.xml.stream.XMLInputFactory
import javax.xml.stream.XMLStreamConstants
import javax.xml.stream.XMLStreamException
import javax.xml.stream.events.Attribute
import javax.xml.stream.events.Characters
import javax.xml.stream.events.EndElement
import javax.xml.stream.events.StartElement
import javax.xml.stream.events.XMLEvent

public class StAXQueryDemo {
   public static void main(String[] args) {
      boolean bFirstName = false
      boolean bLastName = false
      boolean bNickName = false
      boolean bMarks = false
      boolean isRequestRollNo = false
      try {
         XMLInputFactory factory = XMLInputFactory.newInstance()
         XMLEventReader eventReader =
         factory.createXMLEventReader(
            new FileReader("input.txt"))

         String requestedRollNo = "393"
         while(eventReader.hasNext()){
            XMLEvent event = eventReader.nextEvent()
            switch(event.getEventType()){
               case XMLStreamConstants.START_ELEMENT:
                  StartElement startElement = event.asStartElement()
                  String qName = startElement.getName().getLocalPart()
                  if (qName.equalsIgnoreCase("student")) {
                     Iterator<Attribute> attributes = startElement.getAttributes()
                     String rollNo = attributes.next().getValue()
                     if(rollNo.equalsIgnoreCase(requestedRollNo)){
                        System.out.println("Start Element : student")
                        System.out.println("Roll No : " + rollNo)
                        isRequestRollNo = true
                     }
                  } else if (qName.equalsIgnoreCase("firstname")) {
                     bFirstName = true
                  } else if (qName.equalsIgnoreCase("lastname")) {
                     bLastName = true
                  } else if (qName.equalsIgnoreCase("nickname")) {
                     bNickName = true
                  }
                  else if (qName.equalsIgnoreCase("marks")) {
                     bMarks = true
                  }				        
                  break
               case XMLStreamConstants.CHARACTERS:
                  Characters characters = event.asCharacters()
                  if(bFirstName && isRequestRollNo){
                     System.out.println("First Name: " 
                     + characters.getData())
                     bFirstName = false
                  }
                  if(bLastName && isRequestRollNo){
                     System.out.println("Last Name: " 
                     + characters.getData())
                     bLastName = false
                  }
                  if(bNickName && isRequestRollNo){
                     System.out.println("Nick Name: " 
                     + characters.getData())
                     bNickName = false
                  }
                  if(bMarks && isRequestRollNo){
                     System.out.println("Marks: " 
                     + characters.getData())
                     bMarks = false
                  }
                  break
               case  XMLStreamConstants.END_ELEMENT:
                  EndElement endElement = event.asEndElement()
                  if(endElement.getName().getLocalPart().equalsIgnoreCase("student") && isRequestRollNo){
                     System.out.println("End Element : student")
                     System.out.println()
                     isRequestRollNo = false
                  }
               break
            }		    
         }
      } catch (FileNotFoundException e) {
         e.printStackTrace()
      } catch (XMLStreamException e) {
         e.printStackTrace()
      }
   }
}

这将产生以下结果:

Start Element : student
Roll No : 393
First Name: dinkar
Last Name: kad
Nick Name: dinkar
Marks: 85
End Element : student