Android高手进阶教程(二十一)之---Android中创建与几种解析xml的方法!

http://blog.csdn.net/Android_Tutor/article/details/5890835

大家好今天我今天给大家讲解一下android中xml的创建以及一些解析xml的常用方法。

首先是创建，我们用XmlSerializer这个类来创建一个xml文件，其次是解析xml文件，常用的有dom,sax,XmlPullParser等方法，由于sax代码有点复杂，本节只讲解一下dom与XmlPullParser解析，sax我将会在下一节单独讲解,至于几种解析xml的优缺点我就不再讲述了。

为了方便理解，我做了一个简单的Demo。首先首界面有三个按钮，点击第一个按钮会在sdcard目录下创建一个books.xml文件,另外两个按钮分别是调用dom与XmlPullParser方法解析xml文件，并将结果显示在一个TextView里。大家可以按照我的步骤一步步来:

第一步:新建一个Android工程,命名为XmlDemo.

第二步:修改main.xml布局文件，代码如下:

[java] view
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<?xml version="1.0" encoding="utf-8"?>

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

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

>

<Button

android:id="@+id/btn1"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="创建XML文件"

/>

<Button

android:id="@+id/btn2"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="DOM解析XML"

/>

<Button

android:id="@+id/btn3"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="XmlPullParse解析XML"

/>

<TextView

android:id="@+id/result"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

/>

</LinearLayout>

第三步:修改主核心程序XmlDemo.java,代码如下:

[java] view
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package com.tutor.xml;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.NodeList;

import org.xml.sax.SAXException;

import org.xmlpull.v1.XmlPullParser;

import org.xmlpull.v1.XmlPullParserException;

import org.xmlpull.v1.XmlPullParserFactory;

import org.xmlpull.v1.XmlSerializer;

import android.app.Activity;

import android.os.Bundle;

import android.util.Log;

import android.util.Xml;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.TextView;

import android.widget.Toast;

public class XmlDemo extends Activity implements OnClickListener {

private static final String BOOKS_PATH = "/sdcard/books.xml";

private Button mButton1,mButton2,mButton3;

private TextView mTextView;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

setupViews();

}

//初始化工作

private void setupViews(){

mTextView = (TextView)findViewById(R.id.result);

mButton1 = (Button)findViewById(R.id.btn1);

mButton2 = (Button)findViewById(R.id.btn2);

mButton3 = (Button)findViewById(R.id.btn3);

mButton1.setOnClickListener(this);

mButton2.setOnClickListener(this);

mButton3.setOnClickListener(this);

}

//创建xml文件

private void createXmlFile(){

File linceseFile = new File(BOOKS_PATH);

try{

linceseFile.createNewFile();

}catch (IOException e) {

Log.e("IOException", "exception in createNewFile() method");

}

FileOutputStream fileos = null;

try{

fileos = new FileOutputStream(linceseFile);

}catch (FileNotFoundException e) {

Log.e("FileNotFoundException", "can't create FileOutputStream");

}

XmlSerializer serializer = Xml.newSerializer();

try {

serializer.setOutput(fileos,"UTF-8");

serializer.startDocument(null, true);

serializer.startTag(null, "books");

for(int i = 0; i < 3; i ++){

serializer.startTag(null, "book");

serializer.startTag(null, "bookname");

serializer.text("Android教程" + i);

serializer.endTag(null, "bookname");

serializer.startTag(null, "bookauthor");

serializer.text("Frankie" + i);

serializer.endTag(null, "bookauthor");

serializer.endTag(null, "book");

}

serializer.endTag(null, "books");

serializer.endDocument();

serializer.flush();

fileos.close();

} catch (Exception e) {

Log.e("Exception","error occurred while creating xml file");

}

Toast.makeText(getApplicationContext(), "创建xml文件成功!", Toast.LENGTH_SHORT).show();

}

//dom解析xml文件

private void domParseXML(){

File file = new File(BOOKS_PATH);

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

DocumentBuilder db = null;

try {

db = dbf.newDocumentBuilder();

} catch (ParserConfigurationException e) {

e.printStackTrace();

}

Document doc = null;

try {

doc = db.parse(file);

} catch (SAXException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

Element root = doc.getDocumentElement();

NodeList books = root.getElementsByTagName("book");

String res = "本结果是通过dom解析:" + "/n";

for(int i = 0; i < books.getLength();i++){

Element book = (Element)books.item(i);

Element bookname = (Element)book.getElementsByTagName("bookname").item(0);

Element bookauthor = (Element)book.getElementsByTagName("bookauthor").item(0);

res += "书名: " + bookname.getFirstChild().getNodeValue() + " " +

"作者: " + bookauthor.getFirstChild().getNodeValue() + "/n";

}

mTextView.setText(res);

}

//xmlPullParser解析xml文件

private void xmlPullParseXML(){

String res = "本结果是通过XmlPullParse解析:" + "/n";

try {

XmlPullParserFactory factory = XmlPullParserFactory.newInstance();

XmlPullParser xmlPullParser = factory.newPullParser();

xmlPullParser.setInput(Thread.currentThread().getContextClassLoader()

.getResourceAsStream(BOOKS_PATH), "UTF-8");

int eventType = xmlPullParser.getEventType();

try{

while (eventType != XmlPullParser.END_DOCUMENT) {

String nodeName = xmlPullParser.getName();

switch (eventType) {

case XmlPullParser.START_TAG:

if("bookname".equals(nodeName)){

res += "书名: " + xmlPullParser.nextText() + " ";

}else if("bookauthor".equals(nodeName)){

res += "作者: " + xmlPullParser.nextText() + "/n";

}

break;

default:

break;

}

eventType = xmlPullParser.next();

}

} catch (IOException e) {

e.printStackTrace();

}

} catch (XmlPullParserException e) {

e.printStackTrace();

}

mTextView.setText(res);

}

//按钮事件响应

public void onClick(View v) {

if(v == mButton1){

createXmlFile();

}else if(v == mButton2){

domParseXML();

}else if(v == mButton3){

xmlPullParseXML();

}

}

}

第四步:由于我们在Sd卡上新建了文件，需要增加权限，如下代码(第16行):

[java] view
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<?xml version="1.0" encoding="utf-8"?>

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

package="com.tutor.xml"

android:versionCode="1"

android:versionName="1.0">

<application android:icon="@drawable/icon" android:label="@string/app_name">

<activity android:name=".XmlDemo"

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-sdk android:minSdkVersion="7" />

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

</manifest>

第五步:运行上述工程，查看效果:

启动首界面:



点击创建XML文件按钮,生成books.xml文件



books.xml内容如下:

[java] view
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<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>

<books>

<book>

<bookname>Android教程0</bookname>

<bookauthor>Frankie0</bookauthor>

</book>

<book>

<bookname>Android教程1</bookname>

<bookauthor>Frankie1</bookauthor>

</book>

<book>

<bookname>Android教程2</bookname>

<bookauthor>Frankie2</bookauthor>

</book>

</books>

点击DOM解析XML按钮:



点击XmlPullParse解析XML按钮:



Ok~今天就先讲到这里。thx~