Added an automatic updater for new releases.

opsu! will now check for updates upon launching, and will prompt the user to download and run a newer version, if available.
- The remote version file is just the filled "version" file, currently located in the gh-pages branch.
- The new version is downloaded to the working directory, and launched with ProcessBuilder.

Related changes:
- Added "file" property (containing the download URL) to "version" file.
- Added maven-artifact dependency for version comparisons.
- Added methods in Downloads class to retrieve the constructor parameters.
- Moved method for showing exit confirmation dialogs into UI.
- Moved method for reading from URLs into Utils.

Signed-off-by: Jeffrey Han <itdelatrisu@gmail.com>

src/itdelatrisu/opsu/downloads/BloodcatServer.java

@@ -19,15 +19,11 @@
 package itdelatrisu.opsu.downloads;
 
 import itdelatrisu.opsu.ErrorHandler;
+import itdelatrisu.opsu.Utils;
 
-import java.io.BufferedReader;
 import java.io.IOException;
-import java.io.InputStream;
-import java.io.InputStreamReader;
 import java.io.UnsupportedEncodingException;
-import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
-import java.net.SocketTimeoutException;
 import java.net.URL;
 import java.net.URLEncoder;
 
@@ -98,36 +94,15 @@ public class BloodcatServer implements DownloadServer {
 	 * @return the JSON object
 	 * @author Roland Illig (http://stackoverflow.com/a/4308662)
 	 */
-	public static JSONObject readJsonFromUrl(URL url) throws IOException {
-		// open connection
-		HttpURLConnection conn = (HttpURLConnection) url.openConnection();
-		conn.setConnectTimeout(Download.CONNECTION_TIMEOUT);
-		conn.setReadTimeout(Download.READ_TIMEOUT);
-		conn.setUseCaches(false);
-		try {
-			conn.connect();
-		} catch (SocketTimeoutException e) {
-			ErrorHandler.error("Connection to server timed out.", e, false);
-			throw e;
-		}
-
-		if (Thread.interrupted())
-			return null;
-
-		// read JSON
+	private static JSONObject readJsonFromUrl(URL url) throws IOException {
+		String s = Utils.readDataFromUrl(url);
 		JSONObject json = null;
-		try (InputStream in = conn.getInputStream()) {
-			BufferedReader rd = new BufferedReader(new InputStreamReader(in));
-			StringBuilder sb = new StringBuilder();
-			int c;
-			while ((c = rd.read()) != -1)
-				sb.append((char) c);
-			json = new JSONObject(sb.toString());
-		} catch (SocketTimeoutException e) {
-			ErrorHandler.error("Connection to server timed out.", e, false);
-			throw e;
-		} catch (JSONException e1) {
-			ErrorHandler.error("Failed to create JSON object.", e1, true);
+		if (s != null) {
+			try {
+				json = new JSONObject(s);
+			} catch (JSONException e) {
+				ErrorHandler.error("Failed to create JSON object.", e, true);
+			}
 		}
 		return json;
 	}

src/itdelatrisu/opsu/downloads/Download.java

@@ -138,9 +138,19 @@ public class Download {
 			return;
 		}
 		this.localPath = localPath;
-		this.rename = rename;
+		this.rename = Utils.cleanFileName(rename, '-');
 	}
 
+	/**
+	 * Returns the remote download URL.
+	 */
+	public URL getRemoteURL() { return url; }
+
+	/**
+	 * Returns the local path to save the download (after renamed).
+	 */
+	public String getLocalPath() { return (rename != null) ? rename : localPath; }
+
 	/**
 	 * Sets the download listener.
 	 * @param listener the listener to set
@@ -187,9 +197,8 @@ public class Download {
 						rbc.close();
 						fos.close();
 						if (rename != null) {
-							String cleanedName = Utils.cleanFileName(rename, '-');
 							Path source = new File(localPath).toPath();
-							Files.move(source, source.resolveSibling(cleanedName), StandardCopyOption.REPLACE_EXISTING);
+							Files.move(source, source.resolveSibling(rename), StandardCopyOption.REPLACE_EXISTING);
 						}
 						if (listener != null)
 							listener.completed();

src/itdelatrisu/opsu/downloads/DownloadList.java

@@ -18,7 +18,6 @@
 
 package itdelatrisu.opsu.downloads;
 
-import itdelatrisu.opsu.ErrorHandler;
 import itdelatrisu.opsu.downloads.Download.Status;
 
 import java.util.ArrayList;
@@ -27,9 +26,6 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 
-import javax.swing.JOptionPane;
-import javax.swing.UIManager;
-
 /**
  * Maintains the current downloads list.
  */
@@ -37,6 +33,9 @@ public class DownloadList {
 	/** The single instance of this class. */
 	private static DownloadList list = new DownloadList();
 
+	/** The exit confirmation message. */
+	public static final String EXIT_CONFIRMATION = "Beatmap downloads are in progress.\nAre you sure you want to quit opsu!?";
+
 	/** Current list of downloads. */
 	private List<DownloadNode> nodes;
 
@@ -160,20 +159,4 @@ public class DownloadList {
 			}
 		}
 	}
-
-	/**
-	 * Shows a confirmation dialog (used before exiting the game).
-	 * @return true if user selects "yes", false otherwise
-	 */
-	public static boolean showExitConfirmation() {
-		try {
-			UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
-		} catch (Exception e) {
-			ErrorHandler.error("Could not set system look and feel for DownloadList.", e, true);
-		}
-		int n = JOptionPane.showConfirmDialog(null,
-				"Beatmap downloads are in progress.\nAre you sure you want to quit opsu!?",
-				"Warning", JOptionPane.YES_NO_OPTION, JOptionPane.WARNING_MESSAGE);
-		return (n != JOptionPane.YES_OPTION);
-	}
 }

src/itdelatrisu/opsu/downloads/Updater.java

@@ -0,0 +1,219 @@
+/*
+ * opsu! - an open-source osu! client
+ * Copyright (C) 2014, 2015 Jeffrey Han
+ *
+ * opsu! 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, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * opsu! 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 opsu!.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package itdelatrisu.opsu.downloads;
+
+import itdelatrisu.opsu.ErrorHandler;
+import itdelatrisu.opsu.Options;
+import itdelatrisu.opsu.UI;
+import itdelatrisu.opsu.Utils;
+import itdelatrisu.opsu.downloads.Download.DownloadListener;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.StringReader;
+import java.net.URL;
+import java.util.Properties;
+
+import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
+import org.newdawn.slick.util.ResourceLoader;
+
+/**
+ * Handles automatic program updates.
+ */
+public class Updater {
+	/** The single instance of this class. */
+	private static Updater updater = new Updater();
+
+	/** The exit confirmation message. */
+	public static final String EXIT_CONFIRMATION = "An opsu! update is being downloaded.\nAre you sure you want to quit opsu!?";
+
+	/**
+	 * Returns the single instance of this class.
+	 */
+	public static Updater get() { return updater; }
+
+	/** Updater status. */
+	public enum Status {
+		INITIAL (""),
+		CHECKING ("Checking for updates..."),
+		CONNECTION_ERROR ("Connection error."),
+		INTERNAL_ERROR ("Internal error."),
+		UP_TO_DATE ("Up to date!"),
+		UPDATE_AVAILABLE ("Update available!\nClick to download."),
+		UPDATE_DOWNLOADING ("Downloading update...") {
+			@Override
+			public String getDescription() {
+				Download d = updater.download;
+				if (d != null && d.getStatus() == Download.Status.DOWNLOADING) {
+					return String.format("Downloading update...\n%.1f%% complete (%s/%s)",
+							d.getProgress(), Utils.bytesToString(d.readSoFar()), Utils.bytesToString(d.contentLength()));
+				} else
+					return super.getDescription();
+			}
+		},
+		UPDATE_DOWNLOADED ("Download complete.\nClick to restart."),
+		UPDATE_FINAL ("Update queued.");
+
+		/** The status description. */
+		private String description;
+
+		/**
+		 * Constructor.
+		 * @param description the status description
+		 */
+		Status(String description) {
+			this.description = description;
+		}
+
+		/**
+		 * Returns the status description.
+		 */
+		public String getDescription() { return description; }
+	};
+
+	/** The current updater status. */
+	private Status status;
+
+	/** The current and latest versions. */
+	private DefaultArtifactVersion currentVersion, latestVersion;
+
+	/** The download object. */
+	private Download download;
+
+	/**
+	 * Constructor.
+	 */
+	private Updater() {
+		status = Status.INITIAL;
+	}
+
+	/**
+	 * Returns the updater status.
+	 */
+	public Status getStatus() { return status; }
+
+	/**
+	 * Returns whether or not the updater button should be displayed.
+	 */
+	public boolean showButton() {
+		return (status == Status.UPDATE_AVAILABLE || status == Status.UPDATE_DOWNLOADED || status == Status.UPDATE_DOWNLOADING);
+	}
+
+	/**
+	 * Returns the version from a set of properties.
+	 * @param props the set of properties
+	 * @return the version, or null if not found
+	 */
+	private DefaultArtifactVersion getVersion(Properties props) {
+		String version = props.getProperty("version");
+		if (version == null || version.equals("${pom.version}")) {
+			status = Status.INTERNAL_ERROR;
+			return null;
+		} else
+			return new DefaultArtifactVersion(version);
+	}
+
+	/**
+	 * Checks the program version against the version file on the update server.
+	 */
+	public void checkForUpdates() throws IOException {
+		if (status != Status.INITIAL)
+			return;
+
+		status = Status.CHECKING;
+
+		// get current version
+		Properties props = new Properties();
+		props.load(ResourceLoader.getResourceAsStream(Options.VERSION_FILE));
+		if ((currentVersion = getVersion(props)) == null)
+			return;
+
+		// get latest version
+		String s = Utils.readDataFromUrl(new URL(Options.VERSION_REMOTE));
+		if (s == null) {
+			status = Status.CONNECTION_ERROR;
+			return;
+		}
+		props = new Properties();
+		props.load(new StringReader(s));
+		if ((latestVersion = getVersion(props)) == null)
+			return;
+
+		// compare versions
+		if (latestVersion.compareTo(currentVersion) <= 0)
+			status = Status.UP_TO_DATE;
+		else {
+			String updateURL = props.getProperty("file");
+			if (updateURL == null) {
+				status = Status.INTERNAL_ERROR;
+				return;
+			}
+			status = Status.UPDATE_AVAILABLE;
+			String localPath = String.format("%s%copsu-update-%s",
+					System.getProperty("user.dir"), File.separatorChar, latestVersion.toString());
+			String rename = String.format("opsu-%s.jar", latestVersion.toString());
+			download = new Download(updateURL, localPath, rename);
+			download.setListener(new DownloadListener() {
+				@Override
+				public void completed() {
+					status = Status.UPDATE_DOWNLOADED;
+					UI.sendBarNotification("Update has finished downloading.");
+				}
+			});
+		}
+	}
+
+	/**
+	 * Starts the download, if available.
+	 */
+	public void startDownload() {
+		if (status != Status.UPDATE_AVAILABLE || download == null || download.getStatus() != Download.Status.WAITING)
+			return;
+
+		status = Status.UPDATE_DOWNLOADING;
+		download.start();
+	}
+
+	/**
+	 * Prepares to run the update when the application closes.
+	 */
+	public void prepareUpdate() {
+		if (status != Status.UPDATE_DOWNLOADED || download == null || download.getStatus() != Download.Status.COMPLETE)
+			return;
+
+		status = Status.UPDATE_FINAL;
+	}
+
+	/**
+	 * Hands over execution to the updated file, if available.
+	 */
+	public void runUpdate() {
+		if (status != Status.UPDATE_FINAL)
+			return;
+
+		try {
+			// TODO: it is better to wait for the process? is this portable?
+			ProcessBuilder pb = new ProcessBuilder("java", "-jar", download.getLocalPath());
+			pb.start();
+		} catch (IOException e) {
+			status = Status.INTERNAL_ERROR;
+			ErrorHandler.error("Failed to start new process.", e, true);
+		}
+	}
+}