Android編程創建與解析xml的常用方法詳解

2019-12-12 02:47:18

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本文實例講述了Android編程創建與解析xml的常用方法。分享給大家供大家參考，具體如下：

今天我今天給大家講解一下Android創建xml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，由于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，至于幾種解析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，并將結果顯示在一個TextView里。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：

<?xmlversion="1.0"encoding="utf-8"?><LinearLayoutxmlns: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 extendsActivity implementsOnClickListener {  privatestatic final String BOOKS_PATH = "/sdcard/books.xml";  privateButton mButton1, mButton2, mButton3;  privateTextView mTextView;  @Override  publicvoid onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.main);    setupViews();  }  // 初始化工作  privatevoid 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  privatevoid 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  privatevoid 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  privatevoid 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");      inteventType = xmlPullParser.getEventType();      try{        while(eventType != XmlPullParser.END_DOCUMENT) {          String nodeName = xmlPullParser.getName();          switch(eventType) {          caseXmlPullParser.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  publicvoid onClick(View v) {    if(v == mButton1) {      createXmlFile();    }else if(v == mButton2) {      domParseXML();    }else if(v == mButton3) {      xmlPullParseXML();    }  }}

第四步：由于我們在Sd卡上新建了文件，需要增加權限，如下代碼(第13行)：

<?xmlversion="1.0"encoding="utf-8"?><manifestxmlns:android="http://schemas.android.com/apk/res/android"  package="com.tutor.xml"android:versionCode="1"android:versionName="1.0">  <applicationandroid:icon="@drawable/icon"android:label="@string/app_name">    <activityandroid:name=".XmlDemo"android:label="@string/app_name">      <intent-filter>        <actionandroid:name="android.intent.action.MAIN"/>        <categoryandroid:name="android.intent.category.LAUNCHER"/>      </intent-filter>    </activity>  </application>  <uses-sdkandroid:minSdkVersion="7"/>  <uses-permissionandroid: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：

<?xmlversion='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：