/*
* Copyright (c) 2001-2007 Sun Microsystems, Inc. All rights reserved.
*
* The Sun Project JXTA(TM) Software License
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The end-user documentation included with the redistribution, if any, must
* include the following acknowledgment: "This product includes software
* developed by Sun Microsystems, Inc. for JXTA(TM) technology."
* Alternately, this acknowledgment may appear in the software itself, if
* and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
* not be used to endorse or promote products derived from this software
* without prior written permission. For written permission, please contact
* Project JXTA at http://www.jxta.org.
*
* 5. Products derived from this software may not be called "JXTA", nor may
* "JXTA" appear in their name, without prior written permission of Sun.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SUN
* MICROSYSTEMS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* JXTA is a registered trademark of Sun Microsystems, Inc. in the United
* States and other countries.
*
* Please see the license information page at :
* <http://www.jxta.org/project/www/license.html> for instructions on use of
* the license in source files.
*
* ====================================================================
*
* This software consists of voluntary contributions made by many individuals
* on behalf of Project JXTA. For more information on Project JXTA, please see
* http://www.jxta.org.
*
* This license is based on the BSD license adopted by the Apache Foundation.
*/
package net.jxta.util;
import net.jxta.logging.Logging;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* This util class provides methods needed by class construction factories.
*
* @see net.jxta.document.StructuredDocumentFactory
* @see net.jxta.document.AdvertisementFactory
* @see net.jxta.id.IDFactory
* @see net.jxta.endpoint.WireFormatMessageFactory
*/
public abstract class ClassFactory<K, I> {
/**
* Logger
*/
private static final transient Logger LOG = Logger.getLogger(ClassFactory.class.getName());
/**
* Standard constructor.
*/
protected ClassFactory() {}
/**
* Used by ClassFactory methods to get the mapping of keys to constructors.
*
* @return the map containing the mappings.
*/
protected abstract Map<K, I> getAssocTable();
/**
* Used by ClassFactory methods to ensure that all keys used with the
* mapping are of the correct type.
*
* @return Class object of the key type.
*/
protected abstract Class<K> getClassForKey();
/**
* Return all of the available keys for this factory.
*
* @return Iterator of all the available keys for this factory.
*/
public Iterator<K> getAvailableKeys() {
return Collections.unmodifiableSet(getAssocTable().keySet()).iterator();
}
/**
* Returns an unmodifiable Set containing all of the associations
* stored in this ClassFactory.
*
* @return Set containing all of the available entries for this factory.
*/
public Set<Map.Entry<K, I>> getEntrySet() {
return Collections.unmodifiableSet(getAssocTable().entrySet());
}
/**
* Used by ClassFactory methods to ensure that all of the instance classes
* which register with this factory have the correct base class
*
* @return Class object of the "Factory" type.
*/
protected abstract Class<I> getClassOfInstantiators();
/**
* Given a resource bundle identifier and a property name register instance
* classes. The property must be a string containing class names which must
* be found on the current class path. The class names are separated by
* spaces.
*
* @param resourceName name of the resource bundle
* @param propertyName name of the property.
* @return boolean true if at least one instance class could be registered
* with this factory.
* @exception MissingResourceException if the resource bundle or
* property cannot be located.
*/
protected boolean registerFromResources(String resourceName, String propertyName) throws MissingResourceException {
ResourceBundle jxtaRsrcs = ResourceBundle.getBundle(resourceName);
String fromProps = jxtaRsrcs.getString(propertyName).trim();
return registerFromString(fromProps);
}
/**
* Register instance classes given a string containing class names which
* must be found on the current class path. The class names are separated
* by spaces.
*
* @param classNamesString The class name list
* @return boolean true if at least one of the instance classes could be
* registered otherwise false.
*/
protected boolean registerFromString(String classNamesString) {
boolean registeredSomething = false;
if ((null == classNamesString) || (0 == classNamesString.length())) {
return false;
}
// make sure the static initialisers for each instance class are called.
List<String> instanceClasses = Arrays.asList(classNamesString.split("\\s"));
for (String eachInstanceClass : instanceClasses) {
try {
registeredSomething |= registerAssoc(eachInstanceClass);
} catch (Exception allElse) {
if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
LOG.log(Level.WARNING, "Failed to register \'" + eachInstanceClass + "\'", allElse);
}
}
}
return registeredSomething;
}
/**
* Given an provider interface name register instance classes. The class
* path is searched for service provider lists as described by the JAR File
* specification for service providers
*
* @param interfaceName name of the implemented interface.
* @return boolean true if at least one instance class could be registered
* with this factory.
*/
protected boolean registerProviders(String interfaceName) {
ClassLoader loader = getClass().getClassLoader();
boolean registeredSomething = false;
try {
Enumeration<URL> providerLists = loader.getResources("META-INF/services/" + interfaceName);
while (providerLists.hasMoreElements()) {
try {
URI providerList = providerLists.nextElement().toURI();
registeredSomething |= registerFromFile(providerList);
} catch (URISyntaxException badURI) {
if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
LOG.log(Level.WARNING, "Failed to convert service URI", badURI);
}
}
}
} catch (IOException ex) {
if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
LOG.log(Level.WARNING, "Failed to locate provider lists", ex);
}
}
return registeredSomething;
}
/**
* Register instance classes given a URI to a file containing class names
* which must be found on the current class path. The class names are listed
* on separate lines. Comments are marked with a '#', the pound sign and
* any following text on any line in the file are ignored.
*
* @param providerList the URI to a file containing a list of providers
* @return boolean true if at least one of the instance classes could be
* registered otherwise false.
*/
protected boolean registerFromFile(URI providerList) {
boolean registeredSomething = false;
InputStream urlStream = null;
try {
urlStream = providerList.toURL().openStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(urlStream, "UTF-8"));
String provider;
while ((provider = reader.readLine()) != null) {
int comment = provider.indexOf('#');
if (comment != -1) {
provider = provider.substring(0, comment);
}
provider = provider.trim();
if (provider.length() > 0) {
try {
registeredSomething |= registerAssoc(provider);
} catch (Exception allElse) {
if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
LOG.log(Level.WARNING, "Failed to register \'" + provider + "\'", allElse);
}
}
}
}
} catch (IOException ex) {
LOG.log(Level.WARNING, "Failed to read provider list " + providerList, ex);
return false;
} finally {
if(null != urlStream) {
try {
urlStream.close();
} catch(IOException ignored) {
}
}
}
return registeredSomething;
}
/**
* Register a class with the factory from its class name. Since class name
* doesn't tell us much, we just load the class and hope that something
* happens as a result of the class loading. This class is often overridden
* in class factories to interogate the instance class before registering
* the instance class.
*
* @param className The class name which will be registered.
* @return boolean true if the class was registered otherwise false.
* @throws Exception when an error occurs.
*/
protected boolean registerAssoc(final String className) throws Exception {
boolean registeredSomething = false;
try {
/*
* This implementation skankily assumes that the class registers
* itself as part of class initialization.
*/
Class ignored = Class.forName(className);
registeredSomething = true;
} catch (ClassNotFoundException ignored) {
if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
LOG.warning("Failed to locate \'" + className + "\'");
}
} catch (NoClassDefFoundError ignored) {
if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
LOG.warning("Failed to locate \'" + className + "\'");
}
}
return registeredSomething;
}
/**
* Register a key and instance class with the factory.
*
* @param key The key to register.
* @param instantiator The instantiator object which will be registered for this key.
* @return boolean true if the key was successfully registered otherwise false.
*/
protected boolean registerAssoc(final K key, final I instantiator) {
// Check the association table to make sure this key is not already present.
if (null != getAssocTable().get(key)) {
return false;
}
getAssocTable().put(key, instantiator);
if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
LOG.fine("Factory : " + getClass().getName() + " Registered instantiator \'" + instantiator + "\' for \'" + key + "\'");
}
return true;
}
/**
* Return the instantiator associated with the provided key.
*
* @param key The identifier for the Instantiator class to be returned.
* @return Instantiator Instantiator matching the provided key
* @throws NoSuchElementException if the key has not been registered.
*/
protected I getInstantiator(final K key) throws NoSuchElementException {
// Get the constructors for this key.
I instantiator = getAssocTable().get(key);
if (null == instantiator) {
throw new NoSuchElementException("key '" + key + "' not registered.");
}
return instantiator;
}
}