Android中创建与几种解析xml的方法!

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a1405 2012-03-26 14:59:00

文章标签 新建工程优缺点命名 Android 文章分类 Android 移动开发

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，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: