Android开发8——利用pull解析器读写XML文件

一、基本介绍

对XML解析有SAX和DOM等多种方式，Android中极力推荐xmlpull方式解析xml。xmlpull不仅可用在Android上同样也适用于javase，但在javase环境中需自己获取xmlpull所依赖的类库，kxml2-2.3.0.jar，xmlpull_1_1_3_4c.jar。

jar包下载网址
http://www.xmlpull.org/
http://kxml.sourceforge.net/

二、例子

读取到xml的声明返回数字0 START_DOCUMENT;
读取到xml的结束返回数字1 END_DOCUMENT ;
读取到xml的开始标签返回数字2 START_TAG
读取到xml的结束标签返回数字3 END_TAG
读取到xml的文本返回数字4 TEXT

<?xml version="1.0" encoding="UTF-8"?>
<people>
	<person id="001">
		<name>XY1</name>
		<age>22</age>
	</person>
	<person id="002">
		<name>XY2</name>
		<age>22</age>
	</person>
</people>

package cn.xy.service;

import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

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

import android.util.Xml;
import cn.xy.model.Person;

/**
 * 利用pull解析器解析XML
 * 
 * @author XY
 * 
 */
public class PersonService
{
	/**
	 * 从XML文件中读取数据
	 * 
	 * @param xml XML文件输入流
	 */
	public List<Person> getPeople(InputStream xml) throws Exception
	{
		List<Person> lst = null;
		Person person = null;

		// 利用ANDROID提供的API快速获得pull解析器
		XmlPullParser pullParser = Xml.newPullParser();

		// 设置需要解析的XML数据
		pullParser.setInput(xml, "UTF-8");

		// 取得事件
		int event = pullParser.getEventType();

		// 若为解析到末尾
		while (event != XmlPullParser.END_DOCUMENT) // 文档结束
		{
			String nodeName = pullParser.getName();
			switch (event)
			{
				case XmlPullParser.START_DOCUMENT: // 文档开始
					lst = new ArrayList<Person>();
					break;
				case XmlPullParser.START_TAG: // 标签开始
					if ("person".equals(nodeName))
					{
						String id = pullParser.getAttributeValue(0);
						person = new Person();
						person.setId(id);
					}
					if ("name".equals(nodeName))
					{
						String name = pullParser.nextText();
						person.setName(name);
					}
					if ("age".equals(nodeName))
					{
						int age = Integer.valueOf(pullParser.nextText());
						person.setAge(age);
					}
					break;
				case XmlPullParser.END_TAG: // 标签结束
					if ("person".equals(nodeName))
					{
						lst.add(person);
						person = null;
					}
					break;
			}
			event = pullParser.next(); // 下一个标签
		}
		return lst;
	}

	/**
	 * 向XML写入数据
	 * 
	 * @param os
	 * @param person
	 * @throws Exception
	 */
	public void saveDataToXML(OutputStream os, List<Person> lst) throws Exception
	{
		XmlSerializer xs = Xml.newSerializer();
		xs.setOutput(os, "UTF-8");
		xs.startDocument("UTF-8", true);
		xs.startTag(null, "people");
		for (Person p : lst)
		{
			xs.startTag(null, "person");
			xs.attribute(null, "person", p.getId());

			xs.startTag(null, "name");
			xs.text(p.getName());
			xs.endTag(null, "name");

			xs.startTag(null, "age");
			xs.text(p.getAge().toString());
			xs.endTag(null, "age");

			xs.endTag(null, "person");
		}
		xs.endTag(null, "people");
		xs.endDocument();
		os.flush();
		os.close();
	}
}

public class TestClass extends AndroidTestCase
{
	public void testPeople() throws Exception
	{
		PersonService ps = new PersonService();
		InputStream xml = this.getClass().getClassLoader().getResourceAsStream("person.xml");
		List<Person> lst = ps.getPeople(xml);
		Assert.assertEquals("XY1", lst.get(0).getName());
	}

	public void testSave() throws Exception
	{
		PersonService ps = new PersonService();
		List<Person> lst = new ArrayList<Person>();
		lst.add(new Person("0001", "XY0001", 20));
		lst.add(new Person("0002", "XY0002", 20));
		File xmlFile = new File(this.getContext().getFilesDir(), "xy.xml"); // data/data/package name/files
		OutputStream os = new FileOutputStream(xmlFile);
		ps.saveDataToXML(os, lst);
	}
}