de.schlichtherle.io.GlobalArchiveDriverRegistry Maven / Gradle / Ivy
/*
* Copyright (C) 2007-2010 Schlichtherle IT Services
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package de.schlichtherle.io;
import de.schlichtherle.io.util.SuffixSet;
import de.schlichtherle.util.ClassLoaders;
import java.io.IOException;
import java.io.InputStream;
import java.io.Serializable;
import java.net.URL;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* A global registry for archive file suffixes and archive drivers which is
* configured by the set of all configuration files on the class path.
* This registry does not have a delegate, so it can only be used as the tail
* in a {@link ArchiveDriverRegistry registry chain}.
*
* When this class is instantiated, it enumerate all instances of the relative
* path META-INF/services/de.schlichtherle.io.registry.properties
* on the class path (this ensures that TrueZIP is compatible with JNLP as used
* by Java Web Start and can be safely added to the Extension Class Path).
*
* The configuration files are processed in arbitrary order.
* However, configuration files which contain the entry
* {@code DRIVER=true} have lesser priority and will be overruled by
* any other configuration files which do not contain this entry.
* This is used by the default configuration file in TrueZIP's JAR:
* It contains this entry in order to allow any client application provided
* configuration file to overrule it.
*
* This class may appear to be a singleton (there's not much point in
* having multiple instances of this class, all with the same configuration).
* However, it actually isn't a true singleton because it's
* {@link Serializable} in order to support serialization of {@link File}
* instances.
* This implies that a JVM can send an instance of this class to another JVM,
* which's own global archive driver registry instance may be configured
* completely different by its local configuration files.
* This requires that the
* {@link de.schlichtherle.io.archive.spi.ArchiveDriver}s used by the global
* archive driver registry are serializable, too.
*
* Note that it's actually discouraged to serialize {@link File} instances.
* It's only supported due to the implementation of this feature in its base
* class {@code java.io.File}.
* Instead of serializing {@link File} instances, a client application
* should serialize path names instead, which are plain strings.
*
* @author Christian Schlichtherle
* @version $Id: GlobalArchiveDriverRegistry.java,v 1.7 2010/08/25 17:08:14 christian_schlichtherle Exp $
* @since TrueZIP 6.5
*/
final class GlobalArchiveDriverRegistry extends ArchiveDriverRegistry {
private static final long serialVersionUID = 1579600190374703884L;
private static final String CLASS_NAME
= "de.schlichtherle.io.GlobalArchiveDriverRegistry";
private static final Logger logger
= Logger.getLogger(CLASS_NAME, CLASS_NAME);
private static final String KWD_NULL = "NULL"; // NOI18N
private static final String KWD_ALL = "ALL"; // NOI18N
private static final String PROP_KEY_DEFAULT_SUFFIXES
= "de.schlichtherle.io.default";
private static final String PROP_KEY_REGISTRY
= "de.schlichtherle.io.registry";
/** The (pseudo) singleton instance. */
public static final GlobalArchiveDriverRegistry INSTANCE
= new GlobalArchiveDriverRegistry();
/**
* The canonical list of archive file suffixes in the global registry
* which have been configured to be recognized by default.
*/
public final String defaultSuffixes;
/**
* The canonical list of all archive file suffixes in the global registry.
*/
public final String allSuffixes;
static {
logger.config("banner"); // NOI18N
}
/**
* Creates a new {@code GlobalArchiveDriverRegistry}.
* This constructor logs some configuration messages at
* {@code Level.CONFIG}.
* If an exception occurs during processing of the configuration resource
* files or no archive drivers are registered, then one or more warnings
* messages are logged at {@code Level.WARNING}, but otherwise the
* constructor terminates normally.
* This is to ensure that TrueZIP can be used without throwing exceptions
* in static initializers just because of a bug in a configuration
* resource file.
*/
private GlobalArchiveDriverRegistry() {
registerArchiveDrivers();
// Initialize suffix lists.
// Note that retrieval of the default suffix list must be done first
// in order to remove the DEFAULT key from the drivers map if present.
// The driver lookup would throw an exception on this entry otherwise.
defaultSuffixes = defaultSuffixes().toString();
allSuffixes = suffixes().toString();
logConfiguration();
}
/**
* Returns the ordered list of relative path names for configuration files.
* Prior elements take precedence.
*/
private static String[] getServices() {
return System.getProperty(PROP_KEY_REGISTRY,
"META-INF/services/de.schlichtherle.io.registry.properties" // since TrueZIP 6.5.2 - NOI18N
+ File.pathSeparator
+ "META-INF/services/" + CLASS_NAME + ".properties" // deprecated - NOI18N
+ File.pathSeparator
+ "META-INF/services/de.schlichtherle.io.archive.spi.ArchiveDriver.properties")
.split("\\" + File.pathSeparator); // deprecated - NOI18N
}
private void registerArchiveDrivers() {
final ArchiveDriverRegistry clientRegistry
= new ArchiveDriverRegistry();
final String[] services = getServices();
for (int i = services.length; --i >= 0; )
registerArchiveDrivers(services[i], this, clientRegistry);
putAll(clientRegistry);
}
/**
* Enumerates all resource URLs for {@code service} on the class
* path and calls
* {@link #registerArchiveDrivers(URL, ArchiveDriverRegistry, ArchiveDriverRegistry)}
* on each instance.
*
* Ensures that configuration files specified by client
* applications always override configuration files specified
* by driver implementations.
*/
private static void registerArchiveDrivers(
final String service,
final ArchiveDriverRegistry driverRegistry,
final ArchiveDriverRegistry clientRegistry) {
assert service != null;
assert driverRegistry != null;
assert clientRegistry != null;
final Enumeration urls;
try {
urls = ClassLoaders.getResources(service, GlobalArchiveDriverRegistry.class);
} catch (IOException ex) {
logger.log(Level.WARNING, "lookup.ex", ex); // NOI18N
return;
}
while (urls.hasMoreElements()) {
final URL url = (URL) urls.nextElement();
registerArchiveDrivers(url, driverRegistry, clientRegistry);
}
}
/**
* Loads and processes the given {@code url} in order to register
* the archive drivers in its config resource file.
*/
private static void registerArchiveDrivers(
final URL url,
final ArchiveDriverRegistry driverRegistry,
final ArchiveDriverRegistry clientRegistry) {
assert url != null;
assert driverRegistry != null;
assert clientRegistry != null;
// Load the configuration map from the properties file.
logger.log(Level.CONFIG, "loading", url); // NOI18N
final Properties config = new Properties();
try {
final InputStream in = url.openStream();
try {
config.load(in);
registerArchiveDrivers(config, driverRegistry, clientRegistry);
} finally {
in.close();
}
} catch (IOException ex) {
logger.log(Level.WARNING, "loading.ex", ex); // NOI18N
// Continue normally.
}
}
/**
* Processes the given {@code config} in order to register
* its archive drivers.
*
* @throws NullPointerException If any archive driver ID in the
* configuration is {@code null}.
*/
private static void registerArchiveDrivers(
final Map config,
final ArchiveDriverRegistry driverRegistry,
final ArchiveDriverRegistry clientRegistry) {
assert config != null;
assert driverRegistry != null;
assert clientRegistry != null;
// Consume and process DRIVER entry.
final String driver = (String) config.remove(KWD_DRIVER);
final boolean isDriver = Boolean.TRUE.equals(Boolean.valueOf(driver));
// Select registry and register drivers.
(isDriver ? driverRegistry : clientRegistry).registerArchiveDrivers(
config, false);
}
/**
* Consumes and processes the entry for the keyword {@code DEFAULT}
* in the map.
* If a suffix is specified for which no driver is registered, then a
* warning is logged and the suffix is removed from the return value.
*
* @return The set of suffixes processed by evaluating the value of the
* entry with the key {@code DEFAULT} in the map of drivers.
* May be empty, but never {@code null}.
*/
private SuffixSet defaultSuffixes() {
final SuffixSet set;
final String defaultSuffixesProperty
= System.getProperty(PROP_KEY_DEFAULT_SUFFIXES);
if (defaultSuffixesProperty != null) {
set = new SuffixSet(defaultSuffixesProperty);
} else {
set = (SuffixSet) remove(KWD_DEFAULT);
if (set == null)
return new SuffixSet();
}
final SuffixSet all = suffixes();
boolean clear = false;
boolean addAll = false;
for (final Iterator i = set.originalIterator(); i.hasNext(); ) {
final String suffix = (String) i.next();
if (KWD_NULL.equals(suffix)) {
i.remove();
clear = true;
} else if (KWD_ALL.equals(suffix)) {
i.remove();
addAll = true;
} else if (!all.contains(suffix)) {
i.remove();
logger.log(Level.WARNING, "unknownSuffix", suffix); // NOI18N
}
}
if (clear)
set.clear();
else if (addAll)
set.addAll(all);
return set;
}
private void logConfiguration() {
final Iterator i = entrySet().iterator();
if (i.hasNext()) {
do {
final Map.Entry entry = (Map.Entry) i.next();
logger.log(Level.CONFIG, "driverRegistered", // NOI18N
new Object[] { entry.getKey(), entry.getValue() });
} while (i.hasNext());
logger.log(Level.CONFIG, "allSuffixList", allSuffixes); // NOI18N
if (defaultSuffixes.length() > 0)
logger.log(Level.CONFIG, "defaultSuffixList", defaultSuffixes); // NOI18N
else
logger.config("noDefaultSuffixes"); // NOI18N
} else {
logger.warning("noDriversRegistered"); // NOI18N
}
}
}