android——写xml

在PersonService的基础上，加上savePersons(·····)，这时的PersonService为：

package com.njupt.xml;

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

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

import android.util.Xml;

public class PersonService {

	public List<Person> loadPersons(InputStream in) throws Exception{
		XmlPullParser parser = Xml.newPullParser();
		parser.setInput(in,"UTF-8");
		
		List<Person> persons = new ArrayList<Person>();
		Person p = null;
		
		for(int type = parser.getEventType() ; type != XmlPullParser.END_DOCUMENT ; type = parser.next()){
			
			if(type == XmlPullParser.START_TAG){
				if(parser.getName().equals("person")){
					p = new Person();
					String id = parser.getAttributeValue(0);
					p.setId(Integer.parseInt(id));
					persons.add(p);
					
				}else if(parser.getName().equals("name")){
					String name = parser.nextText();
					p.setName(name);
				}else if(parser.getName().equals("age")){
					String age = parser.nextText();
					p.setAge(Integer.parseInt(age));
				}
			}
		}
		return persons;
	}

	public void savePersons(List<Person> persons,
			FileOutputStream out) throws Exception {

		XmlSerializer serializer = Xml.newSerializer();
		serializer.setOutput(out,"UTF-8");
		
		serializer.startDocument("UTF-8", true);
		serializer.startTag(null, "persons");
		
		for(Person p : persons){
			serializer.startTag(null, "person");
			serializer.attribute(null, "id", p.getId().toString());
			
			serializer.startTag(null, "name");
			serializer.text(p.getName());
			serializer.endTag(null, "name");
			
			serializer.startTag(null, "age");
			serializer.text(p.getAge().toString());
			serializer.endTag(null, "age");
			
			
			serializer.endTag(null, "person");
		}
		serializer.endTag(null, "persons");
		serializer.endDocument();
		
	}
}

2、PersonTest

package com.njupt.xml;

import java.io.FileOutputStream;
import java.io.InputStream;
import java.util.List;

import android.test.AndroidTestCase;

public class PersonTest extends AndroidTestCase{

	public void test1() throws Exception{
		PersonService service = new PersonService();
		InputStream in = PersonTest.class.getClassLoader().getResourceAsStream("persons22.xml");
	    
		List<Person> persons = service.loadPersons(in);
	 
		for(Person p : persons){
			System.out.println(p);
		}
		
		Person p = new Person(4,"allen",20);
		persons.add(p);
		
		service.savePersons(persons,new FileOutputStream("/mnt/sdcard/persons22.xml"));
	}
}

3、Person22.xml

这时生成的person22.xml文件的内容如下(注意，他不会帮我们把xml文件格式化)：

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?><persons><person id="1"><name>范冰冰</name><age>31</age></person><person id="2"><name>林志玲</name><age>38</age></person><person id="3"><name>杨幂</name><age>26</age></person><person id="4"><name>allen</name><age>20</age></person></persons>