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>