OPDS catalogs cache

git-svn-id: https://only.mawhrin.net/repos/FBReaderJ/trunk@1675 6a642e6f-84f6-412e-ac94-c4a38d5a04b0

AndroidManifest.xml

@@ -89,5 +89,6 @@
 		<service android:name="org.geometerplus.android.fbreader.network.ItemsLoadingService" android:process=":networkLibrary" />
 		<activity android:name="org.geometerplus.android.fbreader.network.NetworkBookInfoActivity" android:process=":networkLibrary" android:configChanges="orientation|keyboardHidden" />
 		<receiver android:name="org.geometerplus.android.fbreader.network.BookDownloaderCallback" android:process=":networkLibrary" />
+		<service android:name="org.geometerplus.android.fbreader.network.LibraryInitializationService" android:process=":networkLibrary" />
 	</application>
 </manifest> 

AndroidManifest.xml.pattern

@@ -89,5 +89,6 @@
 		<service android:name="org.geometerplus.android.fbreader.network.ItemsLoadingService" android:process=":networkLibrary" />
 		<activity android:name="org.geometerplus.android.fbreader.network.NetworkBookInfoActivity" android:process=":networkLibrary" android:configChanges="orientation|keyboardHidden" />
 		<receiver android:name="org.geometerplus.android.fbreader.network.BookDownloaderCallback" android:process=":networkLibrary" />
+		<service android:name="org.geometerplus.android.fbreader.network.LibraryInitializationService" android:process=":networkLibrary" />
 	</application>
 </manifest> 

TODO.network

@@ -15,7 +15,8 @@ NP: оповещение об изменениях в namespace'ах проис
 ** Загрузка не из xml, а из OPDS-каталога с расширениями
 	DONE сделать DTD для xml-ей, как в OPDS, вместо существующего
 	DONE перенести xml на сервер
-		** кэширование каталога
+		DONE кэширование каталога
+		** реализовать обновление библиотеки так, чтобы не терялись загруженные элементы дерева
 	** сделать чтение информации о поиске напрямую из каталога
 
 ** Использовать default e-mail при регистрации новых пользователей в AuthenticationDialog (возможно только в Android 2.0+)

data/resources/application/de.xml

@@ -296,6 +296,7 @@
 			<node name="unsupportedOperation" value="Operation wird nicht unterstützt" />
 			<node name="notAnOPDS" toBeTranslated="true" value="This is not an OPDS catalog" />
 			<node name="noRequiredInformation" toBeTranslated="true" value="Required information is not specified in the catalog" />
+			<node name="cacheDirectoryError" toBeTranslated="true" value="Unable to create cache directory" />
 		</node>
 		<node name="emptyCatalogBox">
 			<node name="title" value="Information" />

data/resources/application/en.xml

@@ -295,6 +295,7 @@
 			<node name="unsupportedOperation" value="Unsupported operation" />
 			<node name="notAnOPDS" value="This is not an OPDS catalog" />
 			<node name="noRequiredInformation" value="Required information is not specified in the catalog" />
+			<node name="cacheDirectoryError" value="Unable to create cache directory" />
 		</node>
 		<node name="emptyCatalogBox">
 			<node name="title" value="Information" />

data/resources/application/fr.xml

@@ -296,6 +296,7 @@
 			<node name="unsupportedOperation" value="Opération non supportée"/>
 			<node name="notAnOPDS" toBeTranslated="true" value="This is not an OPDS catalog" />
 			<node name="noRequiredInformation" toBeTranslated="true" value="Required information is not specified in the catalog" />
+			<node name="cacheDirectoryError" toBeTranslated="true" value="Unable to create cache directory" />
 		</node>
 		<node name="emptyCatalogBox">
 			<node name="title" value="Information"/>

data/resources/application/hu.xml

@@ -296,6 +296,7 @@
 			<node name="unsupportedOperation" value="nem támogaott művelet" />
 			<node name="notAnOPDS" toBeTranslated="true" value="This is not an OPDS catalog" />
 			<node name="noRequiredInformation" toBeTranslated="true" value="Required information is not specified in the catalog" />
+			<node name="cacheDirectoryError" toBeTranslated="true" value="Unable to create cache directory" />
 		</node>
 		<node name="emptyCatalogBox">
 			<node name="title" value="Információ" />

data/resources/application/it.xml

@@ -296,6 +296,7 @@
 			<node name="unsupportedOperation" value="Operazione non supportata" />
 			<node name="notAnOPDS" toBeTranslated="true" value="This is not an OPDS catalog" />
 			<node name="noRequiredInformation" toBeTranslated="true" value="Required information is not specified in the catalog" />
+			<node name="cacheDirectoryError" toBeTranslated="true" value="Unable to create cache directory" />
 		</node>
 		<node name="emptyCatalogBox">
 			<node name="title" value="Informazioni" />

data/resources/application/ru.xml

@@ -295,6 +295,7 @@
 			<node name="unsupportedOperation" value="Неподдерживаемая операция" />
 			<node name="notAnOPDS" value="Это не OPDS каталог" />
 			<node name="noRequiredInformation" value="Требуемая информация не найдена в каталоге" />
+			<node name="cacheDirectoryError" value="Не удается создать каталог для кэша" />
 		</node>
 		<node name="emptyCatalogBox">
 			<node name="title" value="Информация" />

data/resources/application/vi.xml

@@ -296,6 +296,7 @@
 			<node name="unsupportedOperation" value="Thao tác không được hỗ trợ" />
 			<node name="notAnOPDS" toBeTranslated="true" value="This is not an OPDS catalog" />
 			<node name="noRequiredInformation" toBeTranslated="true" value="Required information is not specified in the catalog" />
+			<node name="cacheDirectoryError" toBeTranslated="true" value="Unable to create cache directory" />
 		</node>
 		<node name="emptyCatalogBox">
 			<node name="title" value="Thông tin" />

data/resources/application/zh.xml

@@ -296,6 +296,7 @@
 			<node name="unsupportedOperation" value="非法操作" />
 			<node name="notAnOPDS" toBeTranslated="true" value="This is not an OPDS catalog" />
 			<node name="noRequiredInformation" toBeTranslated="true" value="Required information is not specified in the catalog" />
+			<node name="cacheDirectoryError" toBeTranslated="true" value="Unable to create cache directory" />
 		</node>
 		<node name="emptyCatalogBox">
 			<node name="title" value="信息" />

src/org/geometerplus/android/fbreader/network/LibraryInitializationService.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2010 Geometer Plus <contact@geometerplus.com>
+ *
+ * This program 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+package org.geometerplus.android.fbreader.network;
+
+import android.os.Handler;
+import android.os.IBinder;
+import android.os.Message;
+import android.app.Service;
+import android.content.Intent;
+
+
+public class LibraryInitializationService extends Service {
+
+	@Override
+	public IBinder onBind(Intent intent) {
+		return null;
+	}
+
+	@Override
+	public void onStart(Intent intent, int startId) {
+		super.onStart(intent, startId);
+
+		final NetworkView view = NetworkView.Instance();
+		if (!view.isInitialized()) {
+			stopSelf();
+			return;
+		}
+
+		final Handler handler = new Handler() {
+			@Override
+			public void handleMessage(Message msg) {
+				if (msg.what > 0) {
+					view.finishBackgroundUpdate();
+				}
+				stopSelf();
+			}
+		};
+
+		final Thread thread = new Thread(new Runnable() {
+			public void run() {
+				boolean result = false; 
+				try {
+					result = view.runBackgroundUpdate();
+				} finally {
+					handler.sendEmptyMessage(result ? 1 : 0);
+				}
+			}
+		});
+		thread.setPriority(Thread.MIN_PRIORITY);
+		thread.start();
+	}
+}

src/org/geometerplus/android/fbreader/network/NetworkLibraryActivity.java

@@ -21,6 +21,7 @@ package org.geometerplus.android.fbreader.network;
 
 import android.app.AlertDialog;
 import android.content.DialogInterface;
+import android.content.Intent;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
@@ -59,10 +60,6 @@ public class NetworkLibraryActivity extends NetworkBaseActivity {
 	@Override
 	public void onResume() {
 		super.onResume();
-		tryResume();
-	}
-
-	private void tryResume() {
 		if (!NetworkView.Instance().isInitialized()) {
 			new Initializator().start();
 		} else {
@@ -114,6 +111,7 @@ public class NetworkLibraryActivity extends NetworkBaseActivity {
 			if (message.what == 0) {
 				runInitialization(); // run initialization process
 			} else if (message.obj == null) {
+				startService(new Intent(getApplicationContext(), LibraryInitializationService.class));
 				prepareView(); // initialization is complete successfully
 			} else {
 				processResults((String) message.obj); // handle initialization error

src/org/geometerplus/android/fbreader/network/NetworkView.java

@@ -79,6 +79,19 @@ class NetworkView {
 		return null;
 	}
 
+	// This method must be called from background thread
+	public boolean runBackgroundUpdate() {
+		return NetworkLibrary.Instance().runBackgroundUpdate();
+	}
+
+	// This method MUST be called from main thread
+	// This method can be called only after runBackgroundUpdate method has returned true
+	public void finishBackgroundUpdate() {
+		NetworkLibrary library = NetworkLibrary.Instance();
+		library.finishBackgroundUpdate();
+		library.synchronize();
+		fireModelChangedInternal();
+	}
 
 	/*
 	 * NetworkLibraryItem's actions

src/org/geometerplus/fbreader/Paths.java

@@ -29,4 +29,8 @@ public abstract class Paths {
 	public static String cacheDirectory() {
 		return BooksDirectoryOption.getValue() + "/.FBReader";
 	}
+
+	public static String networkCacheDirectory() {
+		return cacheDirectory() + "/cache";
+	}
 }

src/org/geometerplus/fbreader/network/Base64EncodedImage.java

@@ -23,6 +23,8 @@ import java.io.*;
 
 import org.geometerplus.zlibrary.core.image.ZLBase64EncodedImage;
 
+import org.geometerplus.fbreader.Paths;
+
 final class Base64EncodedImage extends ZLBase64EncodedImage {
 
 	private static final String ENCODED_SUFFIX = ".base64";
@@ -36,7 +38,7 @@ final class Base64EncodedImage extends ZLBase64EncodedImage {
 	}
 
 	public static String makeImagesDir() {
-		return NetworkImage.makeImagesDir() + File.separator + "base64";
+		return Paths.networkCacheDirectory() + "/base64";
 	}
 
 	public void setData(String data) {

src/org/geometerplus/fbreader/network/NetworkImage.java

@@ -23,7 +23,7 @@ import java.io.*;
 import java.net.*;
 
 import org.geometerplus.zlibrary.core.image.ZLSingleImage;
-import org.geometerplus.zlibrary.core.network.*;
+import org.geometerplus.zlibrary.core.network.ZLNetworkManager;
 
 import org.geometerplus.fbreader.Paths;
 
@@ -40,15 +40,11 @@ public final class NetworkImage extends ZLSingleImage {
 	public NetworkImage(String url, String mimeType) {
 		super(mimeType);
 		Url = url;
-		new File(makeImagesDir()).mkdirs();
+		new File(Paths.networkCacheDirectory()).mkdirs();
 	}
 
 	private static final String TOESCAPE = "<>:\"|?*\\";
 
-	public static String makeImagesDir() {
-		return Paths.cacheDirectory() + File.separator + "cache";
-	}
-
 	// mimeType string MUST be interned
 	public static String makeImageFileName(String url, String mimeType) {
 		URI uri;
@@ -65,7 +61,7 @@ public final class NetworkImage extends ZLSingleImage {
 			path.delete(0, 4);
 		}
 		path.insert(0, File.separator);
-		path.insert(0, makeImagesDir());
+		path.insert(0, Paths.networkCacheDirectory());
 
 		int index = path.length();
 
@@ -191,24 +187,7 @@ public final class NetworkImage extends ZLSingleImage {
 				return;
 			}
 
-			ZLNetworkManager.Instance().perform(new ZLNetworkRequest(Url) {
-				public String handleStream(URLConnection connection, InputStream inputStream) throws IOException {
-					OutputStream outStream = new FileOutputStream(imageFile);
-					try {
-						final byte[] buffer = new byte[8192];
-						while (true) {
-							final int size = inputStream.read(buffer);
-							if (size <= 0) {
-								break;
-							}
-							outStream.write(buffer, 0, size);
-						}
-					} finally {
-						outStream.close();
-					}
-					return null;
-				}
-			});
+			ZLNetworkManager.Instance().downloadToFile(Url, imageFile);
 		} finally {
 			mySynchronized = true;
 		}

src/org/geometerplus/fbreader/network/NetworkLibrary.java

@@ -232,15 +232,11 @@ public class NetworkLibrary {
 	public String initialize() {
 		final LinksComparator comparator = new LinksComparator(); 
 
-		final String url = "http://data.fbreader.org/catalogs/generic-1.0.xml";
-
-		final String error = ZLNetworkManager.Instance().perform(
-			OPDSLinkReader.loadOPDSLinksRequest(url, new OnNewLinkListener() {
+		final String error = OPDSLinkReader.loadOPDSLinks(false, new OnNewLinkListener() {
 			public void onNewLink(INetworkLink link) {
 				addLinkInternal(myLoadedLinks, link, comparator);
 			}
-			})
-		);
+		});
 
 		if (error != null) {
 			synchronized (myLinks) {
@@ -262,9 +258,84 @@ public class NetworkLibrary {
 			}
 		);
 
+		/*testDate(new ATOMUpdated(2010,  1,  1,  1,  0,  0,  0,  2,  0),
+				 new ATOMUpdated(2009, 12, 31, 23,  0,  0,  0,  0,  0));
+		testDate(new ATOMUpdated(2010, 12, 31, 23, 40,  0,  0, -1, -30),
+				 new ATOMUpdated(2011,  1,  1,  1, 10,  0,  0,  0,  0));
+		testDate(new ATOMUpdated(2010,  1, 31, 23, 40,  0,  0, -1, -30),
+				 new ATOMUpdated(2010,  2,  1,  1, 10,  0,  0,  0,  0));
+		testDate(new ATOMUpdated(2010,  2, 28, 23, 40,  0,  0, -1, -30),
+				 new ATOMUpdated(2010,  3,  1,  1, 10,  0,  0,  0,  0));
+		testDate(new ATOMUpdated(2012,  2, 28, 23, 40,  0,  0, -1, -30),
+				 new ATOMUpdated(2012,  2, 29,  1, 10,  0,  0,  0,  0));
+		testDate(new ATOMUpdated(2012,  2, 15, 23, 40,  0,  0, -1, -30),
+				 new ATOMUpdated(2012,  2, 16,  1, 10,  0,  0,  0,  0));
+		testDate(new ATOMUpdated(2012,  2, 15, 23, 40,  1,  0,  3, 30),
+				 new ATOMUpdated(2012,  2, 15, 23, 40,  0,  0,  3, 30));
+		testDate(new ATOMUpdated(2012,  2, 15, 23, 40,  0,  0,  3, 30),
+				 new ATOMUpdated(2012,  2, 15, 23, 40,  1,  0,  3, 30));
+		testDate(new ATOMUpdated(2012,  2, 15, 23, 40,  0,  0.001f,  3, 30),
+				 new ATOMUpdated(2012,  2, 15, 23, 40,  0,  0,  3, 30));*/
+
 		return null;
 	}
 
+	/*private void testDate(ATOMDateConstruct date1, ATOMDateConstruct date2) {
+		String sign = " == ";
+		final int diff = date1.compareTo(date2);
+		if (diff > 0) {
+			sign = " > ";
+		} else if (diff < 0) {
+			sign = " < ";
+		}
+		Log.w("FBREADER", "" + date1 + sign + date2);
+	}*/
+
+	private ArrayList<INetworkLink> myBackgroundLinks;
+	private Object myBackgroundLock = new Object();
+
+	// This method must be called from background thread
+	public boolean runBackgroundUpdate() {
+		synchronized (myBackgroundLock) {
+			myBackgroundLinks = new ArrayList<INetworkLink>();
+
+			final String error = OPDSLinkReader.loadOPDSLinks(true, new OnNewLinkListener() {
+				public void onNewLink(INetworkLink link) {
+					myBackgroundLinks.add(link);
+				}
+			});
+
+			if (error != null || myBackgroundLinks.isEmpty()) {
+				myBackgroundLinks = null;
+			}
+
+			if (myBackgroundLinks == null) {
+				return false;
+			} else {
+				Collections.sort(myBackgroundLinks, new LinksComparator());
+				return true;
+			}
+		}
+	}
+
+	// This method MUST be called from main thread
+	// This method can be called only after runBackgroundUpdate method has returned true
+	//
+	// synchronize() method MUST be called after this method
+	public void finishBackgroundUpdate() {
+		synchronized (myBackgroundLock) {
+			if (myBackgroundLinks == null) {
+				throw new RuntimeException("Invalid state: that's impossible!!!");
+			}
+			synchronized (myLinks) {
+				myLoadedLinks.clear();
+				myLoadedLinks.addAll(myBackgroundLinks);
+				invalidate();
+			}
+		}
+	}
+
+
 	public String rewriteUrl(String url, boolean externalUrl) {
 		final String host = ZLNetworkUtil.hostFromUrl(url).toLowerCase();
 		synchronized (myLinks) {

src/org/geometerplus/fbreader/network/atom/ATOMDateConstruct.java

@@ -19,7 +19,7 @@
 
 package org.geometerplus.fbreader.network.atom;
 
-public abstract class ATOMDateConstruct extends ATOMCommonAttributes {
+public abstract class ATOMDateConstruct extends ATOMCommonAttributes implements Comparable<ATOMDateConstruct> {
 
 	public int Year;
 	public int Month;
@@ -278,5 +278,51 @@ public abstract class ATOMDateConstruct extends ATOMCommonAttributes {
 	public String toString() {
 		return getDateTime(false);
 	}
+
+	private static final int[] DAYS_IN_MONTHS = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+	private int daysInMonth(int month, int year) {
+		--month;
+		while (month > 11) month -= 12;
+		while (month < 0) month += 12;
+		if (month == 1 && ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)) {
+			return DAYS_IN_MONTHS[1] + 1;
+		}
+		return DAYS_IN_MONTHS[month];
+	}
+
+	public int compareTo(ATOMDateConstruct date) {
+		int dateYear = date.Year;
+		int dateMonth = date.Month;
+		int dateDay = date.Day;
+		int dateHour = date.Hour;
+		int dateMinutes = date.Minutes;
+		if (TZHour != date.TZHour || TZMinutes != date.TZMinutes) {
+			dateMinutes += TZMinutes - date.TZMinutes;
+			while (dateMinutes < 0) { dateMinutes += 60; --dateHour; }
+			while (dateMinutes > 59) { dateMinutes -= 60; ++dateHour; }
+			dateHour += TZHour - date.TZHour;
+			while (dateHour < 0) { dateHour += 24; --dateDay; }
+			while (dateHour > 23) { dateHour -= 24; ++dateDay; }
+			while (dateDay < 1) dateDay += daysInMonth(--dateMonth, dateYear);
+			while (dateDay > daysInMonth(dateMonth, dateYear)) dateDay -= daysInMonth(dateMonth++, dateYear);
+			while (dateMonth < 1) { dateMonth += 12; --dateYear; }
+			while (dateMonth > 12) { dateMonth -= 12; ++dateYear; }
+		}
+		if (Year != dateYear) return Year - dateYear;
+		if (Month != dateMonth) return Month - dateMonth;
+		if (Day != dateDay) return Day - dateDay;
+		if (Hour != dateHour) return Hour - dateHour;
+		if (Minutes != dateMinutes) return Minutes - dateMinutes;
+		if (Seconds != date.Seconds) return Seconds - date.Seconds;
+		return Math.round(100 * SecondFraction) - Math.round(100 * date.SecondFraction);
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (!(obj instanceof ATOMDateConstruct)) {
+			return false;
+		}
+		return compareTo((ATOMDateConstruct) obj) == 0;
+	}
 };
 

src/org/geometerplus/fbreader/network/opds/OPDSLinkReader.java

@@ -19,18 +19,23 @@
 
 package org.geometerplus.fbreader.network.opds;
 
-import java.io.IOException;
-import java.io.InputStream;
-import java.net.URLConnection;
-import java.util.*;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.util.HashMap;
+import java.util.Map;
 
-import org.geometerplus.zlibrary.core.network.ZLNetworkRequest;
+import org.geometerplus.zlibrary.core.network.ZLNetworkManager;
 
+import org.geometerplus.fbreader.Paths;
 import org.geometerplus.fbreader.network.*;
+import org.geometerplus.fbreader.network.atom.ATOMUpdated;
 
 
 public class OPDSLinkReader {
 
+	static final String CATALOGS_URL = "http://data.fbreader.org/catalogs/generic-1.0.xml";
+
 	public static ICustomNetworkLink createCustomLink(int id, String siteName, String title, String summary, String icon, Map<String, String> links) {
 		if (siteName == null || title == null || links.get(INetworkLink.URL_MAIN) == null) {
 			return null;
@@ -44,13 +49,71 @@ public class OPDSLinkReader {
 		return new OPDSCustomLink(ICustomNetworkLink.INVALID_ID, siteName, null, null, null, links);
 	}
 
-	public static ZLNetworkRequest loadOPDSLinksRequest(String url, final NetworkLibrary.OnNewLinkListener listener) {
-		return new ZLNetworkRequest(url) {
-			@Override
-			public String handleStream(URLConnection connection, InputStream inputStream) throws IOException {
-				new OPDSLinkXMLReader(listener).read(inputStream);
+
+	public static String loadOPDSLinks(boolean updateNotLoad, final NetworkLibrary.OnNewLinkListener listener) {
+		final File dirFile = new File(Paths.networkCacheDirectory());
+		if (!dirFile.exists() && !dirFile.mkdirs()) {
+			return NetworkErrors.errorMessage("cacheDirectoryError");
+		}
+
+		final String fileName = "fbreader_catalogs-"
+			+ CATALOGS_URL.substring(CATALOGS_URL.lastIndexOf(File.separator) + 1);
+
+		boolean goodCache = false;
+		File oldCache = null;
+		ATOMUpdated cacheUpdatedTime = null;
+		final File catalogsFile = new File(dirFile, fileName);
+		if (catalogsFile.exists()) {
+			if (updateNotLoad) {
+				try {
+					final OPDSLinkXMLReader reader = new OPDSLinkXMLReader();
+					reader.read(new FileInputStream(catalogsFile));
+					cacheUpdatedTime = reader.getUpdatedTime();
+				} catch (FileNotFoundException e) {
+					throw new RuntimeException("That's impossible!!!", e); 
+				}
+
+				final long diff = System.currentTimeMillis() - catalogsFile.lastModified();
+				final long valid = 7 * 24 * 60 * 60 * 1000; // one week in milliseconds; FIXME: hardcoded const
+				if (diff >= 0 && diff <= valid) {
+					goodCache = true;
+				} else {
+					oldCache = new File(dirFile, "_" + fileName);
+					oldCache.delete();
+					if (!catalogsFile.renameTo(oldCache)) {
+						catalogsFile.delete();
+						oldCache = null;
+					}
+				}
+			} else {
+				goodCache = true;
+			}
+		}
+
+		String error = null;
+		if (!goodCache) {
+			error = ZLNetworkManager.Instance().downloadToFile(CATALOGS_URL, catalogsFile);
+		}
+
+		if (error != null) {
+			if (oldCache == null) {
+				return error;
+			}
+			catalogsFile.delete();
+			if (!oldCache.renameTo(catalogsFile)) {
+				oldCache.delete();
+				return error;
+			}
+		} else if (oldCache != null) {
+			oldCache.delete();
+			oldCache = null;
+		}
+
+		try {
+			new OPDSLinkXMLReader(listener, cacheUpdatedTime).read(new FileInputStream(catalogsFile));
+		} catch (FileNotFoundException e) {
+			throw new RuntimeException("That's impossible!!!", e); 
+		}
 		return null;
 	}
-		};
-	}
 }

src/org/geometerplus/fbreader/network/opds/OPDSLinkXMLReader.java

@@ -31,6 +31,7 @@ import org.geometerplus.fbreader.network.INetworkLink;
 import org.geometerplus.fbreader.network.NetworkImage;
 import org.geometerplus.fbreader.network.NetworkLibrary;
 import org.geometerplus.fbreader.network.atom.ATOMLink;
+import org.geometerplus.fbreader.network.atom.ATOMUpdated;
 import org.geometerplus.fbreader.network.authentication.NetworkAuthenticationManager;
 import org.geometerplus.fbreader.network.authentication.litres.LitResAuthenticationManager;
 
@@ -45,8 +46,12 @@ public class OPDSLinkXMLReader extends OPDSXMLReader {
 		private final LinkedList<URLRewritingRule> myUrlRewritingRules = new LinkedList<URLRewritingRule>();
 		private HashMap<RelationAlias, String> myRelationAliases = new HashMap<RelationAlias, String>();
 
-		public LinkReader(NetworkLibrary.OnNewLinkListener listener) {
+		private ATOMUpdated myUpdatedTime;
+		private ATOMUpdated myReadAfterTime;
+
+		public LinkReader(NetworkLibrary.OnNewLinkListener listener, ATOMUpdated readAfter) {
 			myListener = listener;
+			myReadAfterTime = readAfter;
 		}
 
 		public void setAuthenticationType(String type) {
@@ -72,6 +77,10 @@ public class OPDSLinkXMLReader extends OPDSXMLReader {
 			myRelationAliases.clear();
 		}
 
+		public ATOMUpdated getUpdatedTime() {
+			return myUpdatedTime;
+		}
+
 		private static final String ENTRY_ID_PREFIX = "urn:fbreader-org-catalog:";
 
 		public boolean processFeedEntry(OPDSEntry entry) {
@@ -185,13 +194,33 @@ public class OPDSLinkXMLReader extends OPDSXMLReader {
 			return opdsLink;
 		}
 
-		public boolean processFeedMetadata(OPDSFeedMetadata feed, boolean beforeEntries) { return false; }
-		public void processFeedStart() {}
-		public void processFeedEnd() {}
+		public boolean processFeedMetadata(OPDSFeedMetadata feed, boolean beforeEntries) {
+			myUpdatedTime = feed.Updated;
+			if (myUpdatedTime != null && myReadAfterTime != null
+					&& myUpdatedTime.compareTo(myReadAfterTime) <= 0) {
+				return true;
+			}
+			return myListener == null; // no listener -- no need to proceed
 		}
 
-	public OPDSLinkXMLReader(NetworkLibrary.OnNewLinkListener listener) {
-		super(new LinkReader(listener));
+		public void processFeedStart() {
+			myUpdatedTime = null;
+		}
+
+		public void processFeedEnd() {
+		}
+	}
+
+	public OPDSLinkXMLReader() {
+		super(new LinkReader(null, null));
+	}
+
+	public OPDSLinkXMLReader(NetworkLibrary.OnNewLinkListener listener, ATOMUpdated readAfter) {
+		super(new LinkReader(listener, readAfter));
+	}
+
+	public ATOMUpdated getUpdatedTime() {
+		return ((LinkReader) myFeedReader).getUpdatedTime();
 	}
 
 	private String myFBReaderNamespaceId;

src/org/geometerplus/zlibrary/core/network/ZLNetworkManager.java

@@ -196,4 +196,30 @@ public class ZLNetworkManager {
 		}
 		return message.toString();
 	}
+
+
+	public final String downloadToFile(String url, final File outFile) {
+		return downloadToFile(url, outFile, 8192);
+	}
+
+	public final String downloadToFile(String url, final File outFile, final int bufferSize) {
+		return perform(new ZLNetworkRequest(url) {
+			public String handleStream(URLConnection connection, InputStream inputStream) throws IOException {
+				OutputStream outStream = new FileOutputStream(outFile);
+				try {
+					final byte[] buffer = new byte[bufferSize];
+					while (true) {
+						final int size = inputStream.read(buffer);
+						if (size <= 0) {
+							break;
+						}
+						outStream.write(buffer, 0, size);
+					}
+				} finally {
+					outStream.close();
+				}
+				return null;
+			}
+		});
+	}
 }