CheckUpdatesThread.java

//    This file is part of Penn TotalRecall <http://memory.psych.upenn.edu/TotalRecall>.
//
//    TotalRecall is free software: you can redistribute it and/or modify
//    it under the terms of the GNU General Public License as published by
//    the Free Software Foundation, version 3 only.
//
//    TotalRecall is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU General Public License for more details.
//
//    You should have received a copy of the GNU General Public License
//    along with TotalRecall.  If not, see <http://www.gnu.org/licenses/>.

package util;

import info.Constants;
import info.SysInfo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;




/**
 * Checks remote server (in a separate thread) for updates and informs user accordingly.
 * 
 * Notifications are handled through JOptionPane dialogs.
 * A separate thread is used so network problems won't hold up the event dispatch thread.
 * This class is inherently thread-safe since it does not change the state of other objects.
 * 
 * @author Yuvi Masory
 */
public class CheckUpdatesThread implements Runnable {

	private boolean informEitherWay;
	
	/**
	 * Creates a new update checking thread.
	 * User is always notified if updates are available.
	 * 
	 * @param informEitherWay <tt>true</tt> if the user should be notified if updates are not available.
	 */
	public CheckUpdatesThread(boolean informEitherWay) {
		this.informEitherWay = informEitherWay;
	}
	
	/**
	 * Thread body.
	 * 
	 * Opens a connection to a remote server, parses an version file, and informs user if an update is available.
	 */
	public void run() {
//		System.out.println("-- Checking for Updates --");
		if(updateAvailable()) {
			informUpdate();
		}
		else {
//			System.out.println("No update available\n");
			if(informEitherWay) {
				informNoUpdate();
			}
		}
	}

	/**
	 * Launches dialog to notify user an update is available.
	 */
	private static void informUpdate() {
		String message = "An new version of " + Constants.programName + " is available!\n" +
		"Please visit " + Constants.downloadSite + " to download.";
		GiveMessage.infoMessage(message);
	}

	/**
	 * Launches dialog to inform user no update is available.
	 */
	private static void informNoUpdate() {
		GiveMessage.infoMessage("You are running the latest version of " + Constants.programName + "!");
	}

	/**
	 * Does the work of opening the connection and parsing the version file.
	 * Returns <tt>false</tt> if there is a network error, handling exceptions internally.
	 * 
	 * @return <tt>true</tt> if the version file indicates a more recent program version is available.
	 */
	private static boolean updateAvailable() {
		URL url = null;
		try {
			url = new URL(SysInfo.sys.updateAddress);
			URLConnection connection = url.openConnection();
			connection.setRequestProperty("User-Agent", Constants.programName + " v" + Constants.programVersion + " java" + System.getProperty("java.version"));
			InputStream is = connection.getInputStream();
			BufferedReader br = new BufferedReader(new InputStreamReader(is));
			String firstLine = br.readLine();
			if(firstLine != null) {
				ProgramVersion curVersion = ProgramVersion.getCurrentVersionNumber();
				ProgramVersion newestVersion = ProgramVersion.getSavedVersionNumber(firstLine);
				if(curVersion.compareTo(newestVersion) < 0) {
					return true;
				}
			}
			return false;
		} 
		catch (MalformedURLException e) {
			e.printStackTrace();
			return false;
		} 
		catch (IOException e) {
			e.printStackTrace();
			return false;
		}
	}
}