文件存储 DOM操作

使用文件保存数据固然很方便，都是如果现在数据较多的话，管理起来就不方便，所以使用文件保存时，

往往会采用XML文件形式进行数据的保存，那么就要对XML文件进行解析，而DOM解析就是最常用

的一种方式。

在AndroidManifest.xml中配置权限

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.li.dom"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk android:minSdkVersion="10" />

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

<application

android:icon="@drawable/ic_launcher"

android:label="@string/app_name" >

<activity

android:name=".MyDOMDemo"

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>

</manifest>

在main.xml中：

<?xml version="1.0" encoding="utf-8"?>

<TableLayout

xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent">

<TableRow

android:gravity="center_horizontal"

android:layout_margin="8dp">

<TextView

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="姓名：" />

<EditText

android:id="@+id/name"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="李叶文" />

</TableRow>

<TableRow

android:gravity="center_horizontal">

<TextView

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="邮箱：" />

<EditText

android:id="@+id/email"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="helloliyewen@163.com" />

</TableRow>

<TableRow

android:layout_marginLeft="30dp">

<Button

android:id="@+id/but"

android:layout_width="60dp"

android:layout_height="wrap_content"

android:text="保存" />

</TableRow>

</TableLayout>

在MyDOMDemo.java程序中

package com.li.dom;

import java.io.File;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import javax.xml.transform.OutputKeys;

import javax.xml.transform.Transformer;

import javax.xml.transform.TransformerConfigurationException;

import javax.xml.transform.TransformerException;

import javax.xml.transform.TransformerFactory;

import javax.xml.transform.dom.DOMSource;

import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import android.app.Activity;

import android.os.Bundle;

import android.os.Environment;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

public class MyDOMDemo extends Activity {

private EditText name = null ;

private EditText email = null ;

private Button but = null ;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

super.setContentView(R.layout.main);

this.name = (EditText) super.findViewById(R.id.name) ;

this.email = (EditText) super.findViewById(R.id.email) ;

this.but = (Button) super.findViewById(R.id.but) ;

this.but.setOnClickListener(new OnClickListenerImpl()) ;

}

private class OnClickListenerImpl implements OnClickListener{

public void onClick(View v) {

if (!Environment.getExternalStorageState().equals(

Environment.MEDIA_MOUNTED)) { // 不存在不操作

return; // 返回到程序的被调用处

}

File file = new File(Environment.getExternalStorageDirectory()

+ File.separator + "liyewen" + File.separator

+ "test.xml"); // 要输出文件的路径

if (!file.getParentFile().exists()) { // 父路径不存在

file.getParentFile().mkdirs() ; // 创建父文件夹

}

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance() ;

DocumentBuilder builder = null ;

try {

builder = factory.newDocumentBuilder() ;

} catch (ParserConfigurationException e) {

e.printStackTrace();

}

Document doc = null ;

doc = builder.newDocument() ; // 创建一个新的文档

Element addresslist = doc.createElement_x("addresslist") ;

Element linkman = doc.createElement_x("linkman") ;

Element name = doc.createElement_x("name") ;

Element email = doc.createElement_x("email") ;

name.appendChild(doc.createTextNode(MyDOMDemo.this.name.getText()

.toString()));

email.appendChild(doc.createTextNode(MyDOMDemo.this.email.getText()

.toString()));

linkman.appendChild(name) ;

linkman.appendChild(email) ;

addresslist.appendChild(linkman) ;

doc.appendChild(addresslist) ;

TransformerFactory tf = TransformerFactory.newInstance() ;

Transformer t = null ;

try {

t = tf.newTransformer() ;

} catch (TransformerConfigurationException e) {

e.printStackTrace();

}

t.setOutputProperty(OutputKeys.ENCODING, "GBK") ;

DOMSource source = new DOMSource(doc);

StreamResult result = new StreamResult(file) ;

try {

t.transform(source, result) ;

} catch (TransformerException e) {

e.printStackTrace();

}

}

}

}