黎活明8天快速掌握android视频教程--15_采用Pull解析器解析和生成XML内容

1、该项目主要有下面的两个作用

（1）将xml文件解析成对象的List对象，xml文件可以来自手机本地，也可以来自服务器返回的xml数据

（2）强list对象保存成xml文件，xml保存到手机的内存卡上

Android项目也是采用mvc的框架

在手机的存储空间中保存wy目录下了存在person.xml文件

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
<Persons>
    <person id="23">
        <name>wee</name>
        <age>21</age>
    </person>
    <person id="24">
        <name>wee4</name>
        <age>24</age>
    </person>
    <person id="23">
        <name>wee5</name>
        <age>27</age>
    </person>
</Persons>

我们要对这个xml文件进行解析

我们要看解析的业务类：

package contract.test.service;

import android.content.Context;
import android.util.Log;
import android.util.Xml;
import android.widget.Toast;

import org.xml.sax.helpers.XMLReaderFactory;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;
import org.xmlpull.v1.XmlSerializer;

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

import contract.test.domain.Person;

public class XmlPullParse {

    private Context context;
    private List<Person> persons = null;
    Person person = null;

    public XmlPullParse(Context context) {

        this.context = context;
    }

    public List<Person> xmlPullParse(InputStream xml) throws Exception {

       /* *//*兴建一个pull解析器*//*
        XmlPullParser xmlPullParse = XmlPullParserFactory.newInstance().newPullParser();
        //设置解析器的输入流及其解析格式
        xmlPullParse.setInput(xml, "UTF-8");
        Log.i("weiyuan", "23232223");
        int envetType = xmlPullParse.getEventType();
        Toast.makeText(context, "文件打开失败或者sdcard写保护！", Toast.LENGTH_LONG).show();
        while (envetType != xmlPullParse.END_DOCUMENT) {
            *//*解析到了文档的开始：<?xml version="1.0" encoding="UTF-8"?>  *//*
            if (envetType == xmlPullParse.START_DOCUMENT) {
                persons = new ArrayList<Person>();
            }

           *//* 元素节点开始*//*
            if (envetType == xmlPullParse.START_TAG) {

                if ("person".equals(xmlPullParse.getName())) {
                    person = new Person();
                    int id = new Integer(xmlPullParse.getAttributeName(0));
                    person.setId(id);
                }
                if ("name".equals(xmlPullParse.getName())) {
                    String name = xmlPullParse.nextText();
                    person.setName(name);
                }
                if ("age".equals(xmlPullParse.getName())) {
                    int age = new Integer(xmlPullParse.nextText());
                    person.setAge(age);
                }

            }
            if(envetType==xmlPullParse.END_TAG)
            {
                if("person".equals(xmlPullParse.getName()))
                {
                    persons.add(person);
                    person = null;
                }
            }

            envetType = xmlPullParse.next();

        }

        Toast.makeText(context, "535335！", Toast.LENGTH_LONG).show();

          return  persons;
    }*/
        List<Person> persons = null;
        Person person = null;
        XmlPullParser parser = Xml.newPullParser();//得到解析器
        parser.setInput(xml, "UTF-8");//xml编码的utf-8格式
        int eventType = parser.getEventType();//产生第一个事件
        while(eventType!=XmlPullParser.END_DOCUMENT){//只要不是文档结束事件
            switch (eventType) {
                case XmlPullParser.START_DOCUMENT:
                    persons = new ArrayList<Person>();
                    break;

                case XmlPullParser.START_TAG:
                    String name = parser.getName();//获取解析器当前指向的元素的名称
                    if("person".equals(name)){
                        person = new Person();
                        person.setId(new Integer(parser.getAttributeValue(0)));//这里0表示当前元素节点只有一个属性值，获得第二个属性值可用
                        //parser.getAttributeValue(1)
                    }
                    if(person!=null){
                        if("name".equals(name)){
                            person.setName(parser.nextText());//获取解析器当前指向元素的下一个文本节点的值
                        }
                        if("age".equals(name)){
                            person.setAge(new Integer(parser.nextText()));
                        }
                    }
                    break;
                case XmlPullParser.END_TAG:
                    if("person".equals(parser.getName())){
                        persons.add(person);
                        person = null;
                    }
                    break;
            }
            eventType = parser.next();
        }
        return persons;

}

    /*保存数据到xml中，保存到sd卡的当前目录下的123.xml中*/
    public  void saveToXml(OutputStream output,List<Person>persons) throws XmlPullParserException, IOException
    {
        //建立输出破解器
        XmlSerializer xmlSerializer = XmlPullParserFactory.newInstance().newSerializer();
        xmlSerializer.setOutput(output,"UTF-8");
        xmlSerializer.startDocument("UTF-8",true);

        xmlSerializer.startTag(null,"Persons");
        for(Person person:persons)
        {
            xmlSerializer.startTag(null,"person");
            xmlSerializer.attribute(null,"id", person.getId().toString());
            xmlSerializer.startTag(null,"name");
            xmlSerializer.text(person.getName());
            xmlSerializer.endTag(null,"name");
            xmlSerializer.startTag(null,"age");
            xmlSerializer.text(person.getAge().toString());
            xmlSerializer.endTag(null,"age");

            xmlSerializer.endTag(null,"person");
        }
        xmlSerializer.endTag(null,"Persons");
        xmlSerializer.endDocument();
        output.flush();
        output.close();
    }

}

我们来看下activity的代码：

package contract.test.xmlpullparse;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

import org.xmlpull.v1.XmlPullParserException;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

import contract.test.domain.Person;
import contract.test.service.XmlPullParse;

public class MyActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);
/*从xml中解析数据*/
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {

            Log.i("weiyuan", Environment.getExternalStorageDirectory().getAbsolutePath().toString() + File.separator +
                    "weiyuan");
          /*  File file = new File(Environment.getExternalStorageDirectory().toString() +File.separator+"123.xml");*/
            /*File file = new File(Environment.getExternalStorageDirectory().toString() +"/weiyuan/person.xml"
                    );*/
            //初始化File
            /*几点注意事项
            * 1 我是在sd当前目录下自己手动建立了一个wy的文件夹，该该文件夹下新建了一个person.xml的xml文件
            * 2 要访问该文件夹下的person.xml文件必须保证高文件夹和该文件是可读写的，一般自己在sd卡上手动建立的文件是
            * 受保护的自己要该为不受保护的
            *
            * <元素 元素属性=xxx> 可以存在多个属性
                   <元素2>
                    asdasd
                   </元素2>
                </元素>*/
            /*其中asdasd是文本节点，nextText()函数就是获得asdasd的值*/
            String path=Environment.getExternalStorageDirectory().toString()
                    +File.separator
                    +"wy"
                    +File.separator
                    +"person.xml";
            File file=new File(path);
            if (file.exists()) {
                Toast.makeText(getApplicationContext(), "文件夹存在", Toast.LENGTH_LONG).show();
                Log.i("weiyuan", Environment.getExternalStorageDirectory().toString() + File.separator +
                        "weiyuan");
            }
            else
            {Toast.makeText(getApplicationContext(), "文件夹不存在", Toast.LENGTH_LONG).show();

                try {
                    file.createNewFile();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                Toast.makeText(getApplicationContext(), "xml文件不存在", Toast.LENGTH_LONG).show();
                Log.i("weiyuan", Environment.getExternalStorageDirectory().toString() );
            }
            try {
                InputStream input = new FileInputStream(file);
                /*FileInputStream input = new FileInputStream(file);这也是正确的*/

                XmlPullParse xmlPullParse  = new XmlPullParse(getApplicationContext());
                try {
                    List<Person> persons = xmlPullParse.xmlPullParse(input);
                    for (Person person :persons)
                    {
                        Log.i("weiyuan",person.toString());
                    }
                    Toast.makeText(getApplicationContext(), "文件解析成功！", Toast.LENGTH_LONG).show();

                } catch (Exception e) {
                    e.printStackTrace();
                    Toast.makeText(getApplicationContext(), "文件解析失败", Toast.LENGTH_LONG).show();
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
                Toast.makeText(getApplicationContext(), "文件输入流失败！", Toast.LENGTH_LONG).show();
            }

        } else {
            Toast.makeText(getApplicationContext(), "文件打开失败或者sdcard写保护！", Toast.LENGTH_LONG).show();
        }

        /*将数据保存xml文件中*/
        if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))
        {
            File file = new File(Environment.getExternalStorageDirectory().toString()+File.separator+"123.xml");
            try {
                OutputStream  outputStream = new FileOutputStream(file);
                XmlPullParse xmlPullParse = new XmlPullParse(getApplicationContext());
                List<Person> persons = new ArrayList<Person>();
                persons.add(new Person(23,"wee",21));
                persons.add(new Person(24,"wee4",24));
                persons.add(new Person(23,"wee5",27));
                try {
                    xmlPullParse.saveToXml(outputStream,persons);
                    Toast.makeText(getApplicationContext(), "数据保存到123.xml中成功！", Toast.LENGTH_LONG).show();
                } catch (XmlPullParserException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
        else
        {
            Toast.makeText(getApplicationContext(), "文件打开失败或者sdcard写保护！", Toast.LENGTH_LONG).show();
        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.my, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

person类对象的代码是：

package contract.test.domain;

public class Person {
    private Integer id ; //int 和Integer的最大区别，Integer是类，该类具有透toString方法，可以转换为字符串
    private String name ;
    private  Integer age;

    public Person(Integer id, String name, Integer age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }
    public Person()
    {

    }
    @Override
    public String toString() {
        return "Person{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", 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;
    }
}

注意一定不要忘记了sd卡的使用权限

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="contract.test.xmlpullparse" >

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MyActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>

    <!-- 在SDCard中创建与删除文件权限 -->
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
    <!-- 往SDCard写入数据权限 -->
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
</manifest>