編輯:Android開發實例
大家好今天我今天給大家講解一下android中xml的創建以及一些解析xml的常用方法。
首先是創建,我們用XmlSerializer這個類來創建一個xml文件,其次是解析xml文件,常用的有dom,sax,XmlPullParser等方法,由於sax代碼有點復雜,本節只講解一下dom與XmlPullParser解析,sax我將會在下一節單獨講解,至於幾種解析xml的優缺點我就不再講述了。
為了方便理解,我做了一個簡單的Demo。首先首界面有三個按鈕,點擊第一個按鈕會在sdcard目錄下創建一個books.xml文件,另外兩個按鈕分別是調用dom與XmlPullParser方法解析xml文件,並將結果顯示在一個TextView裡。大家可以按照我的步驟一步步來:
第一步:新建一個Android工程,命名為XmlDemo.
第二步:修改main.xml布局文件,代碼如下:
- <?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="創建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,代碼如下:
- 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);
- }
- //創建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(), "創建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 = "本結果是通過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 += "書名: " + bookname.getFirstChild().getNodeValue() + " " +
- "作者: " + bookauthor.getFirstChild().getNodeValue() + "\n";
- }
- mTextView.setText(res);
- }
- //xmlPullParser解析xml文件
- private void xmlPullParseXML(){
- String res = "本結果是通過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 += "書名: " + 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);
- }
- //按鈕事件響應
- public void onClick(View v) {
- if(v == mButton1){
- createXmlFile();
- }else if(v == mButton2){
- domParseXML();
- }else if(v == mButton3){
- xmlPullParseXML();
- }
- }
- }
第四步:由於我們在Sd卡上新建了文件,需要增加權限,如下代碼(第16行):
- <?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:運行上述工程,查看效果:
啟動首界面:
點擊創建XML文件按鈕,生成books.xml文件
books.xml內容如下:
- <?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>
點擊DOM解析XML按鈕:
點擊XmlPullParse解析XML按鈕:
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