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;

public class PersonService
{

public List getPeople(InputStream xml) throws Exception
{
List 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();
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;
}

public void saveDataToXML(OutputStream os, List 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 lst = ps.getPeople(xml);
Assert.assertEquals("XY1", lst.get(0).getName());
}

public void testSave() throws Exception
{
PersonService ps = new PersonService();
List lst = new ArrayList();
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);
}
}

本文参考自金旭亮老师的《.NET 4.0面向对象编程漫谈》有关代理的内容