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

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 plaincopyprint?

<?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>

[java]
view plaincopyprint?

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();
}
}
}

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 plaincopyprint?

<?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>

[java]
view plaincopyprint?

<?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>

<?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。