18 .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：

<? 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13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~