rssfeedxmldatasource.java

RssFeed阅读器,可以任意加入删除管理任何RSS FEED,采用多性程打开你所关注的新闻内容。

/**
 * 
 */
package RssFeeds;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Set;
import java.util.List;
import java.util.ArrayList;
import java.util.TreeSet;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.DOMImplementation;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;


/**
 * XML file data operation class
 * 
 * @author Jack
 *
 */
public class RssFeedXMLDataSource implements RssFeedDataSource {

	private String inputFile;

    private static Document document;    

	// top level element
	private Element rss;
	private Element rssAdd;
			
	/**
	 * constructor to read the saved feed channels 
	 */   
	public RssFeedXMLDataSource() {
		GetRssFeedFromFile("RssFeed.xml");
	}

	/**
	 * constructor of the class with xml file input
	 * using DOM parser to read xml file
	 * @param input
	 * 		xml file input
	 */
	public RssFeedXMLDataSource(String input) {
		this();
		inputFile = input;
		
		DocumentBuilderFactory factory;
		DocumentBuilder	builder;
		
		try {
			factory = DocumentBuilderFactory.newInstance();
			builder = factory.newDocumentBuilder();
			
			builder.setErrorHandler(new RssFeedErrorHandler());
			
			if(new File(inputFile).exists()) {
				InputSource inputSource = new InputSource(inputFile);
				document = builder.parse(inputSource);
			}
			else {
				DOMImplementation impl = builder.getDOMImplementation();
				document = impl.createDocument(null, "rssAdd", null);
			}
		}catch(ParserConfigurationException e) {
			e.printStackTrace();
		}catch(SAXException e) {
			e.printStackTrace();
		}catch(IOException e) {
			e.printStackTrace();
		}
		
		rssAdd = document.getDocumentElement();
	}

	/**
	 * read xml file to the document using DOM parser
	 * @param input
	 * 		xml file input
	 */
	public void GetRssFeedFromFile(String input) {

		document = null;
		DocumentBuilderFactory savedFactory;
		DocumentBuilder	savedBuilder;
		
		try {
			savedFactory = DocumentBuilderFactory.newInstance();
			savedBuilder = savedFactory.newDocumentBuilder();
			
			savedBuilder.setErrorHandler(new RssFeedErrorHandler());
			
			if(new File(input).exists()) {
				InputSource savedInputSource = new InputSource(input);

				document = savedBuilder.parse(savedInputSource);
			}
			else {
				DOMImplementation savedImpl = savedBuilder.getDOMImplementation();
				document = savedImpl.createDocument(null, "rss", null);
			}
				
		}catch(ParserConfigurationException e) {
			e.printStackTrace();
		}catch(SAXException e) {
			e.printStackTrace();
		}catch(IOException e) {
			e.printStackTrace();
		}
		rss = document.getDocumentElement();
	}

	/**
	 * 	obtain feed title from saved feed channels
	 * @return
	 * 		feed title
	 */
	public String getFeedTitle() {
		String feedtitle;
		
		NodeList feedNodeList = rss.getElementsByTagName("channelTitle");
		// the first node title is the feed title
		if( feedNodeList.getLength() < 1 )
			feedtitle = "";
		else
			feedtitle = feedNodeList.item(0).getTextContent();
		
		return feedtitle;
	}

	/**
	 * reading document to obtain channel title by tag of title 
	 * @return
	 * 		channel title
	 */
	public String getChanTitle() {
		String chanTitle;
		NodeList feedNodeList = rssAdd.getElementsByTagName("title");
		
		if( feedNodeList.getLength() < 1 )
			chanTitle = "";
		else
			chanTitle = feedNodeList.item(0).getTextContent();
		
		return chanTitle;
	}
	
	/**
	 * reading document to obtain channel number by tag of title
	 * @return
	 * 		channel number
	 */
	public int getChanNum() {
		NodeList feedNodeList = rssAdd.getElementsByTagName("title");
		int num = feedNodeList.getLength();
		
		return num;
	}

	/**
	 * obtain all feed items and save them in the RssFeedItem object array list
	 * @return
	 * 		RssFeedItem array list
	 */
	public List<RssFeedItem> getItemOnebyOne() {
		
		List<RssFeedItem> itemList = new ArrayList<RssFeedItem>();
		
		NodeList firstList = rssAdd.getElementsByTagName("item");
		
		for(int i = 0; i < firstList.getLength(); i++) {
			RssFeedItem feedItem = new RssFeedItem();
			Node firstNode = firstList.item(i);
			NodeList secondList = firstNode.getChildNodes();
			int secondLen = secondList.getLength();
			for(int j=0; j<secondLen; j++) {
				Node secondNode = secondList.item(j);
				String tag = secondNode.getNodeName();
				if(tag.equals("title")) {
					feedItem.setItemTitle(secondNode.getTextContent());
				}
				else if(tag.equals("link")) {
					feedItem.setItemlink(secondNode.getTextContent());
				}
				else if(tag.equals("pubDate")) {
					feedItem.setItemPubDate(secondNode.getTextContent());
				}
				else if(tag.equals("description")) {
					feedItem.setItemDescription(secondNode.getTextContent());
				}
				else
					continue;
			}
			itemList.add(feedItem);
		}
		return itemList;
	}
	
	/**
	 * add a new feed
	 * 
	 * @param f
	 * 		XML feed source
	 */
	public void addFeed(RssFeedXMLDataSource f) {
		RssFeedItem feedItem = new RssFeedItem();
		List<RssFeedItem> itemList;
		
		f.GetRssFeedFromFile("RssFeed.xml");
	
		// obtain all item list
		itemList = getItemOnebyOne();
		
		// second level element
		Element channel = document.createElement("channel");
		Element c_title = document.createElement("channelTitle");
		c_title.appendChild(document.createTextNode(getChanTitle()));
		channel.appendChild(c_title);
				
		for(int i = 0; i < itemList.size(); i++ )
		{
			Element item = document.createElement("item");

			// create item' subelements
			Element title = document.createElement("title");
			Element link = document.createElement("link");
			Element description = document.createElement("description");
			Element pubDate = document.createElement("pubDate");
			
			feedItem = itemList.get(i);
			// append text to elements
			title.appendChild(document.createTextNode(feedItem.getItemTitle()));
			link.appendChild(document.createTextNode(feedItem.getItemlink()));
			description.appendChild(document.createTextNode(feedItem.getItemDescription()));
		    pubDate.appendChild(document.createTextNode(feedItem.getItemPubDate()));
		    
	    	// append elements to item
	    	item.appendChild(title);
	    	item.appendChild(link);
	    	item.appendChild(description);
	    	item.appendChild(pubDate);

		    // add two layer elements
		    rss.appendChild(channel).appendChild(item);
		}
    	f.saveDocumentToFile();
	}
	
	/**
	 * delete feed name by the selected feed name
	 * @param f
	 * 		saved XML feed source
	 * @param feedsel
	 * 		the selected feed name
	 */
	public void deletFeedName(RssFeedXMLDataSource f, String feedsel) {
		f.GetRssFeedFromFile("RssFeed.xml");
		NodeList nodes = rss.getElementsByTagName("channel");
		
		for(int i = 0; i < nodes.getLength(); i++) {
			Node channel = nodes.item(i);
			NodeList items = channel.getChildNodes();
			
			for(int j = 0; j < items.getLength(); j++) {
				Node item = items.item(j);
				if(item.getNodeName().equals("channelTitle")) {
					if(feedsel.equals(item.getTextContent())) {
						rss.removeChild(channel);
					}
					else
						break;
				}
			}
		}
		saveDocumentToFile();
	}

	/**
	 * delete feed item by the selected feed name and feed item name
	 * @param f
	 * 		the saved XML feed source
	 * @param feedname
	 * 		the selected feed title
	 * @param itemsel
	 * 		the selected feed item title
	 */
	public void deletFeedItem(RssFeedXMLDataSource f, String feedname, String itemsel) {
		f.GetRssFeedFromFile("RssFeed.xml");
		NodeList nodes = rss.getElementsByTagName("channel");
		
		for(int i = 0; i < nodes.getLength(); i++) {
			Node channel = nodes.item(i);
			NodeList items = channel.getChildNodes();
			
			for(int j = 0; j < items.getLength(); j++) {
				Node item = items.item(j);
				if(item.getNodeName().equals("channelTitle")) {
					if(feedname.equals(item.getTextContent())) {
						//obtain item object
						for(int n = j+1; n < items.getLength(); n++) {
							Node next = items.item(n);
							NodeList nexts = next.getChildNodes();
							Node last0 = nexts.item(0);
							if(itemsel.equals(last0.getTextContent())) {
								channel.removeChild(next);
							}
						}
					}
					else
						break;
				}
				else
					break;
			}
		}
		saveDocumentToFile();
	}

	/**
	 * when window close save the document to file
	 * @see RssFeeds.RssFeedDataSource#close()
	 */
	@Override
	public void close() {
		GetRssFeedFromFile("RssFeed.xml");
		// normalize is called to remove any blank spaces in the document
		document.normalize();
		saveDocumentToFile();
	}


	/**
	 * obtain all channel title from the saved xml file
	 * @see RssFeeds.RssFeedDataSource#feedSet()
	 */
	@Override
	public Set<String> feedSet() {
		
		Set<String> feeds = new TreeSet<String>();

		NodeList feedNodeList = rss.getElementsByTagName("channelTitle");
		
		for (int i = 0; i < feedNodeList.getLength(); i++) {
			String feed = feedNodeList.item(i).getTextContent();
			feeds.add(feed);
		}
		return feeds;
	}

	/**
	 * obtain all item title from the saved xml file and show them
	 * @see RssFeeds.RssFeedDataSource#itemSet()
	 */
	@Override
	public Set<String> itemSet(String str) {
		return searchAndShowItemList(str);
	}
	
	/**
	 * search and show item list by the feed title
	 * @param feedname
	 * 		the selected feed title
	 * @return
	 * 		a set of feed item title
	 */
	public Set<String> searchAndShowItemList(String feedname) {
		Set <String>itemTitleSet = new TreeSet<String>();
		
		NodeList nodes = rss.getElementsByTagName("channel");
				
		for(int i = 0; i < nodes.getLength(); i++) {
			Node channel = nodes.item(i);
			NodeList items = channel.getChildNodes();
			
			for(int j = 0; j < items.getLength(); j++) {
				Node item = items.item(j);
				if(item.getNodeName().equals("channelTitle")) {
					if(feedname.equals(item.getTextContent())) {
						// obtain item title
						for(int n = j+1; n < items.getLength(); n++) {
							Node next = items.item(n);
							NodeList nexts = next.getChildNodes();
							Node last = nexts.item(0);

							String t = last.getTextContent();
							itemTitleSet.add(t);
						}
					}
					else
						break;
				}
				else
					break;
			}
		}
		return itemTitleSet;
	}
	
	/**
	 * obtain one feed item from the saved xml file 
	 * by selected feed title and the item title
	 * @param feedsel
	 * 		the selected feed title
	 * @param itemsel
	 * 		the selected item title
	 * @return
	 * 		the RssFeedItem object
	 */
	public RssFeedItem searchAndShowOneItem(String feedsel, String itemsel) {
		RssFeedItem itemData = new RssFeedItem();
		
		NodeList nodes = rss.getElementsByTagName("channel");
		
		for(int i = 0; i < nodes.getLength(); i++) {
			Node channel = nodes.item(i);
			NodeList items = channel.getChildNodes();
			
			for(int j = 0; j < items.getLength(); j++) {
				Node item = items.item(j);
				if(item.getNodeName().equals("channelTitle")) {
					if(feedsel.equals(item.getTextContent())) {
						// obtain item object
						for(int n = j+1; n < items.getLength(); n++) {
							Node next = items.item(n);
							NodeList nexts = next.getChildNodes();
							Node last0 = nexts.item(0);
							if(itemsel.equals(last0.getTextContent())) {
								Node last1 = nexts.item(1);
								Node last2 = nexts.item(2);
								Node last3 = nexts.item(3);
								
								itemData.setItemTitle(last0.getTextContent());
								itemData.setItemlink(last1.getTextContent());
								itemData.setItemDescription(last2.getTextContent());
								itemData.setItemPubDate(last3.getTextContent());
							}
						}
					}
					else
						break;
				}
				else
					break;
			}
		}
		return itemData;
	}
		
	/**
	 * save the document to the xml when add new or delete feeds and items operation
	 */
	private void saveDocumentToFile() {
		inputFile = "RssFeed.xml";
		TransformerFactory factory = TransformerFactory.newInstance();
		Transformer transformer;
		try {
			transformer = factory.newTransformer();
		    Source source = new DOMSource(document);
		    FileOutputStream out = new FileOutputStream(inputFile);
		    Result output = new StreamResult(out);
		    transformer.transform(source, output);
		} catch (TransformerConfigurationException e) {
			e.printStackTrace();
	    } catch (FileNotFoundException e) {
	    	e.printStackTrace();
	    } catch (TransformerException e) {
		    e.printStackTrace();
		}
	}	
}