Android 中以 SAX/DOM/Pull 解釋 XML

DOMPerson.java

//（2）DOM解析XML文件时，会将XML文件的所有内容读取到内存中，然后允许您使用DOM API遍历XML树、检索所需的数据。
DOMPerson.java
 
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import com.sinber.domain.Person;
public class DOMPerson {
    public static List<Person> getPerson() throws Exception{
        List<Person> pers = new ArrayList<Person>();
        InputStream inStream = SAXPersonService.class.getClassLoader().getResourceAsStream("person.xml");
        DocumentBuilderFactory factory =DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document dom = builder.parse(inStream);
        Element root = dom.getDocumentElement();
        NodeList persons = root.getElementsByTagName("person");
        for(int i=0;i<persons.getLength();i++){
            Element personNode =(Element)persons.item(i);
            Person person = new Person();
            person.setId(new Integer(personNode.getAttribute("id")));
            NodeList childNodes = personNode.getChildNodes();
            for(int j=0;j<childNodes.getLength();j++){
                Node childNode = childNodes.item(j);
                if(childNode.getNodeType()==Node.ELEMENT_NODE){
                    Element element = (Element)childNode;
                    if("name".equals(childNode.getNodeName())){
                        person.setName(new String(element.getFirstChild().getNodeValue()));
                    }else if("age".equals(childNode.getNodeName())){
                        person.setAge(new Short(element.getFirstChild().getNodeValue()));
                    }
                }
            }
            pers.add(person);
        }
        inStream.close();
        return pers;
    }
}

Person.java

//定义一个名为Person的javaBean用于存放上面解析出来的xml内容

public class Person {
    private Integer id;
    private String name;
    private Short age;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Short getAge() {
        return age;
    }

    public void setAge(Short age) {
        this.age = age;
    }
}

person.xml

<?xml version="1.0" encoding="UTF-8"?> 
<persons> 
    <person id="1"> 
      <name>张三</name> 
      <age>22</age> 
    </person> 
    <person id="2"> 
      <name>李四</name> 
      <age>23</age> 
    </person> 
</persons> 

PersonDefaultHandler.java

// (1）使用SAX读取XML文件；它采用的是事件驱动，并不需要解析完整个文档，速度快并且占用内存少。需要为SAX提供实现ContentHandler接口的类。

import java.util.ArrayList;
import java.util.List;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import com.sinber.domain.Person;

public class PersonDefaultHandler extends DefaultHandler {
    private List<Person> persons;
    private Person person ;    //记录当前person
    private String perTag;    //记录前一个标签的名称

    /**
     * 重写父类的开始文档方法。用于初始化
     */
    @Override
    public void startDocument() throws SAXException {
        persons = new ArrayList<Person>();
    }

    @Override
    public void startElement(String uri, String localName, String qName,
            Attributes attributes) throws SAXException {
        if("person".equals(localName)){
            Integer id = new Integer(attributes.getValue(0));    //取id
            person = new Person();
            person.setId(id);
        }
        perTag = localName;
    }

    /**参数：
     * ch        整个XML字符串
     * start     节点值在整个XML字符串中的索引位置
     * length    节点值的长度
     */
    @Override
    public void characters(char[] ch, int start, int length)
            throws SAXException {
        if(perTag!=null){
            String data = new String(ch,start,length); 
            if("name".equals(perTag)){
                person.setName(data);
            }else if("age".equals(perTag)){
                person.setAge(new Short(data));
            }
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName)
            throws SAXException {
        if("person".equals(localName)){
            persons.add(person);
            person = null;
        }
        perTag = null;
    }

    public List<Person> getPersons() {
        return persons;
    }
}

PullPerson.java

//（3）使用Pull解析器读取XML文件

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlSerializer;
import android.os.Environment;
import android.util.Xml;
import com.sinber.domain.Person;
public class PullPerson {
    
    public static void save(List<Person> persons) throws Exception{
        XmlSerializer serializer = Xml.newSerializer();
        File file = new File(Environment.getExternalStorageDirectory(),"person.xml");
        FileOutputStream outStream = new FileOutputStream(file);
        serializer.setOutput(outStream,"UTF-8");
        serializer.startDocument("UTF-8", true);
        serializer.startTag("", "persons");
        for(Person person:persons){
            serializer.startTag("", "person"); //person
            serializer.attribute("", "id", ""+person.getId());
            serializer.startTag("", "name"); //name
            serializer.text(person.getName());
            serializer.endTag("", "name"); //name
            serializer.startTag("", "age"); //age
            serializer.text(person.getAge().toString());
            serializer.endTag("", "age");//age
            
            serializer.endTag("", "person"); //person
        }
        serializer.endTag("", "persons");
        serializer.endDocument();
        outStream.close();
    }

    public static List<Person> getPersons() throws Exception{
        List<Person> persons = null;
        Person person = null;
        XmlPullParser parser= Xml.newPullParser();
        InputStream inStream = PullPersonService.class.getClassLoader().getResourceAsStream("person.xml");
        parser.setInput(inStream, "UTF-8");
        int eventType = parser.getEventType();    //触发第一个事件
        while(eventType!=XmlPullParser.END_DOCUMENT){
            switch(eventType){
            case XmlPullParser.START_DOCUMENT:
                persons = new ArrayList<Person>();
                break;
                
            case XmlPullParser.START_TAG:    //开始元素事件
                if("person".equals(parser.getName())){
                    person = new Person();
                    person.setId(new Integer(parser.getAttributeValue(0)));
                }else if(person!=null){
                    if("name".equals(parser.getName())){
                        person.setName(parser.nextText());
                    }else if("age".equals(parser.getName())){
                        person.setAge(new Short(parser.nextText()));
                    }
                }
                break;
                
            case XmlPullParser.END_TAG:    //结束元素事件
                if("person".equals(parser.getName())){
                    persons.add(person);
                    person = null;
                }
                break;
                
            default:
                break;
            }
            eventType = parser.next();
        }
        return persons;
    }
}

SAXPerson.java

import java.io.InputStream;
import java.util.List;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import com.sinber.domain.Person;
public class SAXPerson{
    public static List<Person> getPerson() throws Exception{
        //通过类装载器获取文件
        InputStream inStream = SAXPersonService.class.getClassLoader().getResourceAsStream("person.xml");
        SAXParserFactory factory = SAXParserFactory.newInstance(); 
        SAXParser saxParser = factory.newSAXParser();
        PersonDefaultHandler handler = new PersonDefaultHandler();
        saxParser.parse(inStream, handler);
        inStream.close();
        
        return handler.getPersons();
    }
}