学步园

1、pull相关介绍

　　pull解析方式和sax类似都是采用事件驱动模式，区别在sax是方法回调，pull是返回数字。因此可以使用一个switch对感兴趣的事件进行处理。

2、代码说明

　　

package com.tjp.service;

import java.io.InputStream;
import java.io.OutputStream;
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.tjp.model.Person;

/**
 * 
 * 使用pull技术解析
 * @author TanJianping
 *
*/
public class PullPersonService {

public static List<Person> getPersons(InputStream inputStream)throws Exception{
        List<Person> persons=null;
        Person person=null;
        XmlPullParser pullParser=Xml.newPullParser();//获得pull解析对象
        pullParser.setInput(inputStream, "UTF-8");//设置文件流
        int eventType=pullParser.getEventType();//获得第一个事件
        while(eventType!=XmlPullParser.END_DOCUMENT){//如果事件不为文档解析结束
            switch (eventType) {
case XmlPullParser.START_DOCUMENT: //开始解析文档
                persons=new ArrayList<Person>();
break;
case XmlPullParser.START_TAG: //开始解析元素
                String name=pullParser.getName();//获得解析器当前指向的元素名称
                if(name.equals("person")){
                    person=new Person();
                    person.setId(Integer.parseInt(pullParser.getAttributeValue(0)));//获得解析器当前指向的元素的属性，根据索引
                }
if(person!=null){
if(name.equals("age")){
                        person.setAge(Integer.parseInt(pullParser.nextText()));//获得解析器当前指向的当前节点的下一个节点的文本值
                    }else if(name.equals("name")){
                        person.setName(pullParser.nextText());
                    }
                }
break;
case XmlPullParser.END_TAG://解析元素结束
                if(pullParser.getName().equals("person")){
                    persons.add(person);
                    person=null;
                }
break;
            }
            eventType=pullParser.next();//解析的下一个节点
        }
return persons;
    }

/**
     * 保存xml
     * @param persons
     * @param outputStream
     * @throws Exception
*/
public static void saveFile(List<Person> persons,OutputStream outputStream)throws Exception{
        XmlSerializer serializer=Xml.newSerializer();//获得pull序列话对象
        serializer.setOutput(outputStream, "UTF-8");//设置xml头部
        serializer.startDocument("UTF-8", true);//文档开始
        serializer.startTag(null, "persons");//设置一个节点
        for(Person person :persons){
            serializer.startTag(null, "person");
            serializer.attribute(null, "id", String.valueOf(person.getId()));//设置节点的属性值
            serializer.startTag(null, "age");
            serializer.text(String.valueOf(person.getAge()));//设置文本值
            serializer.endTag(null, "age");
            serializer.startTag(null, "name");
            serializer.text(String.valueOf(person.getName()));
            serializer.endTag(null, "name");
            serializer.endTag(null, "person");
        }
        serializer.endTag(null, "persons");//结束一个节点
        serializer.endDocument();//文档结束
        outputStream.flush();
        outputStream.close();
    }


/**
     * 保存xml用写入器的方式
     * @param persons
     * @param outputStream
     * @throws Exception
*/
public static void saveFile4Writer(List<Person> persons,Writer writer)throws Exception{
        XmlSerializer serializer=Xml.newSerializer();//获得pull序列话对象
//serializer.setOutput(writer, "UTF-8");//设置xml头部
        serializer.setOutput(writer);
        serializer.startDocument("UTF-8", true);//文档开始
        serializer.startTag(null, "persons");//设置一个节点
        for(Person person :persons){
            serializer.startTag(null, "person");
            serializer.attribute(null, "id", String.valueOf(person.getId()));//设置节点的属性值
            serializer.startTag(null, "age");
            serializer.text(String.valueOf(person.getAge()));//设置文本值
            serializer.endTag(null, "age");
            serializer.startTag(null, "name");
            serializer.text(String.valueOf(person.getName()));
            serializer.endTag(null, "name");
            serializer.endTag(null, "person");
        }
        serializer.endTag(null, "persons");//结束一个节点
        serializer.endDocument();//文档结束
        writer.flush();
        writer.close();
    }
}

    public void testSavePerson4Pull4Writer()throws Exception{
//OutputStream outputStream=this.getContext().openFileOutput("persons.xml", Context.MODE_PRIVATE);
//OutputStreamWriter writer=new OutputStreamWriter(outputStream);
//BufferedWriter bufferedWriter=new BufferedWriter(writer);//用缓冲区
        
        StringWriter stringWriter=new StringWriter();//写入内存
        List<Person> persons=new ArrayList<Person>();
        persons.add(new Person(11,"谭建平1",12));
        persons.add(new Person(12,"谭建平2",22));
        persons.add(new Person(13,"谭建平3",32));
        PullPersonService.saveFile4Writer(persons, stringWriter);

        Log.i(TAG, stringWriter.toString());//从内存中读取
    }