Android中创建与几种解析xml的方法

最新推荐文章于 2022-08-09 17:29:15 发布

yshen_dublin

最新推荐文章于 2022-08-09 17:29:15 发布

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分类专栏： Android 文章标签： android xml layout books null encoding

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本文介绍了一个简单的Android应用，用于创建和解析XML文件。该应用包括创建XML文件的功能，并使用DOM和XmlPullParser两种方法进行解析，最后将解析结果显示在界面上。

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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:

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<?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:

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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();
}
}
}

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):

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