大家好今天我今天给大家讲解一下Android创建xml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：
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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：
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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13行)：
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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：
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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：
