Java tutorial
/* This file is part of Subsonic. Subsonic 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. Subsonic 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 Subsonic. If not, see <http://www.gnu.org/licenses/>. Copyright 2009 (C) Sindre Mehus */ package net.sourceforge.subsonic.service; import net.sourceforge.subsonic.Logger; import net.sourceforge.subsonic.domain.Version; import org.apache.commons.io.IOUtils; import org.apache.http.client.HttpClient; import org.apache.http.client.ResponseHandler; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.BasicResponseHandler; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.params.HttpConnectionParams; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.StringReader; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Date; import java.util.regex.Matcher; import java.util.regex.Pattern; /** * Provides version-related services, including functionality for determining whether a newer * version of Subsonic is available. * * @author Sindre Mehus */ public class VersionService { private static final DateFormat DATE_FORMAT = new SimpleDateFormat("yyyyMMdd"); private static final Logger LOG = Logger.getLogger(VersionService.class); private Version localVersion; private Version latestFinalVersion; private Version latestBetaVersion; private Date localBuildDate; private String localBuildNumber; /** * Time when latest version was fetched (in milliseconds). */ private long lastVersionFetched; /** * Only fetch last version this often (in milliseconds.). */ private static final long LAST_VERSION_FETCH_INTERVAL = 7L * 24L * 3600L * 1000L; // One week /** * URL from which to fetch latest versions. */ private static final String VERSION_URL = "http://subsonic.org/backend/version.view"; /** * Returns the version number for the locally installed Subsonic version. * * @return The version number for the locally installed Subsonic version. */ public synchronized Version getLocalVersion() { if (localVersion == null) { try { localVersion = new Version(readLineFromResource("/version.txt")); LOG.info("Resolved local Subsonic version to: " + localVersion); } catch (Exception x) { LOG.warn("Failed to resolve local Subsonic version.", x); } } return localVersion; } /** * Returns the version number for the latest available Subsonic final version. * * @return The version number for the latest available Subsonic final version, or <code>null</code> * if the version number can't be resolved. */ public synchronized Version getLatestFinalVersion() { refreshLatestVersion(); return latestFinalVersion; } /** * Returns the version number for the latest available Subsonic beta version. * * @return The version number for the latest available Subsonic beta version, or <code>null</code> * if the version number can't be resolved. */ public synchronized Version getLatestBetaVersion() { refreshLatestVersion(); return latestBetaVersion; } /** * Returns the build date for the locally installed Subsonic version. * * @return The build date for the locally installed Subsonic version, or <code>null</code> * if the build date can't be resolved. */ public synchronized Date getLocalBuildDate() { if (localBuildDate == null) { try { String date = readLineFromResource("/build_date.txt"); localBuildDate = DATE_FORMAT.parse(date); } catch (Exception x) { LOG.warn("Failed to resolve local Subsonic build date.", x); } } return localBuildDate; } /** * Returns the build number for the locally installed Subsonic version. * * @return The build number for the locally installed Subsonic version, or <code>null</code> * if the build number can't be resolved. */ public synchronized String getLocalBuildNumber() { if (localBuildNumber == null) { try { localBuildNumber = readLineFromResource("/build_number.txt"); } catch (Exception x) { LOG.warn("Failed to resolve local Subsonic build number.", x); } } return localBuildNumber; } /** * Returns whether a new final version of Subsonic is available. * * @return Whether a new final version of Subsonic is available. */ public boolean isNewFinalVersionAvailable() { Version latest = getLatestFinalVersion(); Version local = getLocalVersion(); if (latest == null || local == null) { return false; } return local.compareTo(latest) < 0; } /** * Returns whether a new beta version of Subsonic is available. * * @return Whether a new beta version of Subsonic is available. */ public boolean isNewBetaVersionAvailable() { Version latest = getLatestBetaVersion(); Version local = getLocalVersion(); if (latest == null || local == null) { return false; } return local.compareTo(latest) < 0; } /** * Reads the first line from the resource with the given name. * * @param resourceName The resource name. * @return The first line of the resource. */ private String readLineFromResource(String resourceName) { InputStream in = VersionService.class.getResourceAsStream(resourceName); if (in == null) { return null; } BufferedReader reader = null; try { reader = new BufferedReader(new InputStreamReader(in)); return reader.readLine(); } catch (IOException x) { return null; } finally { IOUtils.closeQuietly(reader); IOUtils.closeQuietly(in); } } /** * Refreshes the latest final and beta versions. */ private void refreshLatestVersion() { long now = System.currentTimeMillis(); boolean isOutdated = now - lastVersionFetched > LAST_VERSION_FETCH_INTERVAL; if (isOutdated) { try { lastVersionFetched = now; readLatestVersion(); } catch (Exception x) { LOG.warn("Failed to resolve latest Subsonic version.", x); } } } /** * Resolves the latest available Subsonic version by screen-scraping a web page. * * @throws IOException If an I/O error occurs. */ private void readLatestVersion() throws IOException { HttpClient client = new DefaultHttpClient(); HttpConnectionParams.setConnectionTimeout(client.getParams(), 10000); HttpConnectionParams.setSoTimeout(client.getParams(), 10000); HttpGet method = new HttpGet(VERSION_URL + "?v=" + getLocalVersion()); String content; try { ResponseHandler<String> responseHandler = new BasicResponseHandler(); content = client.execute(method, responseHandler); } finally { client.getConnectionManager().shutdown(); } BufferedReader reader = new BufferedReader(new StringReader(content)); Pattern finalPattern = Pattern.compile("SUBSONIC_FULL_VERSION_BEGIN(.*)SUBSONIC_FULL_VERSION_END"); Pattern betaPattern = Pattern.compile("SUBSONIC_BETA_VERSION_BEGIN(.*)SUBSONIC_BETA_VERSION_END"); try { String line = reader.readLine(); while (line != null) { Matcher finalMatcher = finalPattern.matcher(line); if (finalMatcher.find()) { latestFinalVersion = new Version(finalMatcher.group(1)); LOG.info("Resolved latest Subsonic final version to: " + latestFinalVersion); } Matcher betaMatcher = betaPattern.matcher(line); if (betaMatcher.find()) { latestBetaVersion = new Version(betaMatcher.group(1)); LOG.info("Resolved latest Subsonic beta version to: " + latestBetaVersion); } line = reader.readLine(); } } finally { reader.close(); } } }