Android采用Pull解析和生成xml文档

Pull解析和Sax解析很相似，都是轻量级的解析，在Android的内核中已经嵌入了Pull，所以我们不需要再添加第三方jar包来支持Pull。Pull解析和Sax解析不一样的地方有(1)pull读取xml文件后触发相应的事件调用方法返回的是数字(2)pull可以在程序中控制想解析到哪里就可以停止解析

有些时候，我们需要生成一个XML文件，生成XML文件的方法有很多，如：可以只使用一个StringBuilder组拼XML内容，然后把内容写入到文件中；或者使用DOM API生成XML文件，或者也可以使用pull解析器生成XML文件，这里推荐大家使用Pull解析器。

需要解析的xml文件如下
android.xml位置放在src目录下

<?xml version="1.0" encoding="UTF-8"?>
<persons>
	<person id="1">
		<name>张三</name>
		<age>20</age>
	</person>
	<person id="2">
		<name>李四</name>
		<age>30</age>
	</person>
</persons>

将Person对象封装起来的bean为

package com.lamp.domain;

public class Person {
	private Integer id = null;
	private String name = null;
	private Integer age = null;
	public Person(){}
	public Person(int id, String name, int age) {
		this.id = id;
		this.name = name;
		this.age = 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 Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}
}

业务层解析代码如下

package com.lamp.service;

import java.io.IOException;
import java.io.InputStream;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlSerializer;

import android.util.Xml;

import com.lamp.domain.Person;

public class PullPersonService {
	public static String PERSON = "person";
	public static String NAME = "name";
	public static String AGE = "age";
	public static String PERSONS = "persons";
	
	//从xml文件中读取数据
	public static List<Person> pullReadXml(InputStream is) throws Exception {
		List<Person> personList = null;
		Person person = null;
		XmlPullParser parser = Xml.newPullParser();
		parser.setInput(is, "UTF-8");
		int eventCode = parser.getEventType();
		while (eventCode != XmlPullParser.END_DOCUMENT) {
			switch (eventCode) {
			case XmlPullParser.START_DOCUMENT:
				personList = new ArrayList<Person>();
				break;
			case XmlPullParser.START_TAG:
				//判断开始标签元素是否是person
				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());
					}if(AGE.equals(parser.getName())){
						person.setAge(new Integer(parser.nextText()));
					}
				}
				break;

			case XmlPullParser.END_TAG:
				if(PERSON.equals(parser.getName()) && person!=null){
					personList.add(person);
					person = null;
				}
				break;
			}
			//进入下一个元素并触发相应事件
			eventCode = parser.next();
		}
		return personList;
	}
	
	//将数据写入xml文件
	public static void writeToXml(List<Person> personList,Writer writer) throws Exception, IllegalStateException, IOException{
		XmlSerializer serializer = Xml.newSerializer();
		serializer.setOutput(writer);
		serializer.startDocument("UTF-8", true);
		serializer.startTag(null, PERSONS);
		
		for(Person person : personList){
			serializer.startTag(null, PERSON);
			serializer.attribute(null, "id", String.valueOf(person.getId()));
			
			serializer.startTag(null, NAME);
			serializer.text(person.getName());
			serializer.endTag(null, NAME);
			
			serializer.startTag(null, AGE);
			serializer.text(String.valueOf(person.getAge()));
			serializer.endTag(null, AGE);
			
			serializer.endTag(null, PERSON);
		}
		serializer.endTag(null, PERSONS);
		serializer.endDocument();
		writer.flush();
		writer.close();
	} 
}

最后通过JUnit进行测试

package com.lamp.service;

import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.List;

import org.xml.sax.SAXException;

import android.content.Context;
import android.test.AndroidTestCase;
import android.util.Log;

import com.lamp.domain.Person;

public class PersonServiceTest extends AndroidTestCase {
	private static final String TAG = "PersonServiceTest";
	//测试读取xml文件
	public void testReadXML() throws Exception, SAXException, IOException{
		InputStream is = PersonServiceTest.class.getClassLoader().getResourceAsStream("android.xml");
		List<Person> persons = PullPersonService.pullReadXml(is);
		for(Person person : persons){
			Log.i(TAG, person.getName()); 
		}
	}
	
	//测试写xml数据
	public void testWriteToXml() throws Exception{
		//写到手机中
		//FileOutputStream os = this.getContext().openFileOutput("persons.xml", Context.MODE_PRIVATE);
		//写到SDK卡中
		FileOutputStream os = new FileOutputStream(new File(Environment.getExternalStorageDirectory(),"persons.xml"));		
        OutputStreamWriter writer = new OutputStreamWriter(os,"UTF-8");
		BufferedWriter bufWriter = new BufferedWriter(writer);
		List<Person> personList = new ArrayList<Person>();
		personList.add(new Person(1,"张三",30));
		personList.add(new Person(2,"李四",50));
		personList.add(new Person(3,"王五",70));
		PullPersonService.writeToXml(personList, bufWriter);
	}
}