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

转自：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:

<?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:

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):

<?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:

<?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~