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:

<?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>

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>