【Android】SAX解析XML（20110926更新）

SAX是事件驅動型XML解析接口

優點：解析速度快，內存消耗小

适合Android等移动设备

 

示例：

 

在assets建立用於解析的XML文件source.xml

 

<?xml version="1.0" encoding="UTF-8"?>
<xml><android><version>2.1</version><name>Eclair</name></android><android><version>2.2</version><name>Froyo</name></android><android><version>2.3</version><name>Gingerbread</name></android></xml>

 

 新建一個Activity，我們將在ListView中顯示解析結果

 

package lizhen.sax;

import java.io.IOException;
import java.io.InputStream;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import javax.xml.parsers.ParserConfigurationException;

import org.xml.sax.SAXException;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class Main extends Activity {
    
	public static final String TAG = "Main";
	private ListView contentListView;
	private List<Map<String, String>> data = new LinkedList<Map<String,String>>();  //結果數據
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        contentListView = (ListView) findViewById(R.id.main_ContentListView);
        try {
        	InputStream xml = getAssets().open("source.xml"); //從assets中讀入數據源
        	MySAXParser parser = new MySAXParser(); 
			parser.parse(xml); //對輸入流進行解析
			data = parser.getResult(); //獲得解析結果
		} catch (ParserConfigurationException e) {
			Log.e(TAG, e.getMessage());
		} catch (SAXException e) {
			Log.e(TAG, e.getMessage());
		} catch (IOException e) {
			Log.e(TAG, e.getMessage());
		}
        contentListView.setAdapter(new ContentListAdapter(this, data));
    }
    
    private class ContentListAdapter extends BaseAdapter {
    	
    	private Context context;
    	private List<Map<String, String>> data;
    	
    	public ContentListAdapter(Context context, List<Map<String, String>> data) {
    		this.context = context;
    		this.data = data;
    	}
		@Override
		public int getCount() {
			return data.size();
		}
		@Override
		public Object getItem(int position) {
			return data.get(position);
		}
		@Override
		public long getItemId(int position) {
			return position;
		}
		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
			View result = convertView;
			if(result == null) {
				result = LayoutInflater.from(context).inflate(R.layout.main_item, null);
			}
			TextView versionTextView = (TextView) result.findViewById(R.id.main_VersionTextView);
			TextView nameTextView = (TextView) result.findViewById(R.id.main_NameTextView);
			versionTextView.setText(data.get(position).get(MySAXParser.ELEMENT_VERSION));
			nameTextView.setText(data.get(position).get(MySAXParser.ELEMENT_NAME));
			return result;
		}
    	
    } 
    
}

 

SAX解析類

通過繼承DefaultHandler，重寫父類方法，對解析XML的過程中觸發的事件進行响应

DefaultHandler常用的囘調方法有：

• startDocument 文檔開始
• startElement 元素開始
  uri 命名空间URI
  localName 不带命名空间标签的元素名
  qName 带命名空间的元素名
  attributes 元素属性
• characters 元素內部字符數據
  ch 字符数组
  start 字符数组开始位置
  length 使用字符数组的长度
• endElement 元素结束
  uri 命名空间URI
  localName 不带命名空间标签的元素名
  qName 带命名空间的元素名
• endDocument 文檔結尾

 

package lizhen.sax;

import java.io.IOException;
import java.io.InputStream;
import java.io.StringReader;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;

import android.util.Log;

public class MySAXParser {
	
	public static final String ELEMENT_ANDROID = "android";
	public static final String ELEMENT_VERSION = "version";
	public static final String ELEMENT_NAME = "name";
	
	private List<Map<String, String>> result = new LinkedList<Map<String,String>>();
	
	public void parse(InputStream xml) throws ParserConfigurationException, SAXException, IOException {
		SAXParserFactory saxParserFactory = SAXParserFactory.newInstance(); //調用靜態方法newInstance得到SAXParseFactory實例
		SAXParser saxParser = saxParserFactory.newSAXParser(); //調用newSAXParser創建SAXParser對象
		XMLReader xmlReader = saxParser.getXMLReader(); //獲得XMLReader對象
		xmlReader.setContentHandler(new MySAXHandler()); //設置處理XML的Handler
		xmlReader.parse(new InputSource(xml)); //將InputStream裝飾為InputSource，進行解析
	}
	
	private class MySAXHandler extends DefaultHandler {
		
		private String currentElement;
		
		private Map<String, String> android;
		
		@Override
		public void startElement(String uri, String localName, String qName,
				Attributes attributes) throws SAXException {
			super.startElement(uri, localName, qName, attributes);
			currentElement = localName;
			if(ELEMENT_ANDROID.equals(currentElement)) {
				android = new HashMap<String, String>();
			}
		}

		@Override
		public void characters(char[] ch, int start, int length)
				throws SAXException {
			super.characters(ch, start, length);
			if(ELEMENT_VERSION.equals(currentElement)){
				android.put(ELEMENT_VERSION, new String(ch, start, length));
			} else if(ELEMENT_NAME.equals(currentElement)) {
				android.put(ELEMENT_NAME, new String(ch, start, length));
			}
		}

		@Override
		public void endElement(String uri, String localName, String qName)
				throws SAXException {
			super.endElement(uri, localName, qName);
			if(ELEMENT_ANDROID.equals(localName)) {
				result.add(android);
			}
		}
		
	}
	
	public List<Map<String, String>> getResult() {
		return this.result;
	}

}

 

 

運行結果：

评论

1 楼 f839903061 2011-12-11  

能不能用简体字啊？其他的都很好！