| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.felix.dm.impl; |
| |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| |
| import org.osgi.framework.BundleContext; |
| import org.osgi.framework.BundleException; |
| import org.osgi.framework.InvalidSyntaxException; |
| import org.osgi.framework.ServiceEvent; |
| import org.osgi.framework.ServiceListener; |
| import org.osgi.framework.ServiceReference; |
| |
| /** |
| * This class mimics the standard OSGi <tt>LogService</tt> interface. An |
| * instance of this class is used by the dependency manager for all logging. |
| * By default this class logs messages to standard out. The log level can be set to |
| * control the amount of logging performed, where a higher number results in |
| * more logging. A log level of zero turns off logging completely. |
| * |
| * The log levels match those specified in the OSGi Log Service. |
| * This class also tracks log services and will use the highest ranking |
| * log service, if present, as a back end instead of printing to standard |
| * out. The class uses reflection to invoking the log service's method to |
| * avoid a dependency on the log interface. This class is in many ways similar |
| * to the one used in the system bundle for that same purpose. |
| * |
| * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a> |
| */ |
| public class Logger implements ServiceListener { |
| public static final int LOG_ERROR = 1; |
| public static final int LOG_WARNING = 2; |
| public static final int LOG_INFO = 3; |
| public static final int LOG_DEBUG = 4; |
| |
| private final BundleContext m_context; |
| |
| private final static int LOGGER_OBJECT_IDX = 0; |
| private final static int LOGGER_METHOD_IDX = 1; |
| private ServiceReference m_logRef = null; |
| private Object[] m_logger = null; |
| |
| public Logger(BundleContext context) { |
| m_context = context; |
| startListeningForLogService(); |
| } |
| |
| public final void log(int level, String msg) { |
| _log(null, level, msg, null); |
| } |
| |
| public final void log(int level, String msg, Throwable throwable) { |
| _log(null, level, msg, throwable); |
| } |
| |
| public final void log(ServiceReference sr, int level, String msg) { |
| _log(sr, level, msg, null); |
| } |
| |
| public final void log(ServiceReference sr, int level, String msg, Throwable throwable) { |
| _log(sr, level, msg, throwable); |
| } |
| |
| protected void doLog(ServiceReference sr, int level, String msg, Throwable throwable) { |
| String s = (sr == null) ? null : "SvcRef " + sr; |
| s = (s == null) ? msg : s + " " + msg; |
| s = (throwable == null) ? s : s + " (" + throwable + ")"; |
| switch (level) { |
| case LOG_DEBUG: |
| System.out.println("DEBUG: " + s); |
| break; |
| case LOG_ERROR: |
| System.out.println("ERROR: " + s); |
| if (throwable != null) { |
| if ((throwable instanceof BundleException) && (((BundleException) throwable).getNestedException() != null)) { |
| throwable = ((BundleException) throwable).getNestedException(); |
| } |
| throwable.printStackTrace(); |
| } |
| break; |
| case LOG_INFO: |
| System.out.println("INFO: " + s); |
| break; |
| case LOG_WARNING: |
| System.out.println("WARNING: " + s); |
| break; |
| default: |
| System.out.println("UNKNOWN[" + level + "]: " + s); |
| } |
| } |
| |
| private void _log(ServiceReference sr, int level, String msg, Throwable throwable) { |
| // Save our own copy just in case it changes. We could try to do |
| // more conservative locking here, but let's be optimistic. |
| Object[] logger = m_logger; |
| // Use the log service if available. |
| if (logger != null) { |
| _logReflectively(logger, sr, level, msg, throwable); |
| } |
| // Otherwise, default logging action. |
| else { |
| doLog(sr, level, msg, throwable); |
| } |
| } |
| |
| private void _logReflectively(Object[] logger, ServiceReference sr, int level, String msg, Throwable throwable) { |
| if (logger != null) { |
| Object[] params = { sr, new Integer(level), msg, throwable }; |
| try { |
| ((Method) logger[LOGGER_METHOD_IDX]).invoke(logger[LOGGER_OBJECT_IDX], params); |
| } |
| catch (InvocationTargetException ex) { |
| System.err.println("Logger: " + ex); |
| } |
| catch (IllegalAccessException ex) { |
| System.err.println("Logger: " + ex); |
| } |
| } |
| } |
| |
| /** |
| * This method is called when the bundle context is set; |
| * it simply adds a service listener so that the bundle can track |
| * log services to be used as the back end of the logging mechanism. It also |
| * attempts to get an existing log service, if present, but in general |
| * there will never be a log service present since the system bundle is |
| * started before every other bundle. |
| */ |
| private synchronized void startListeningForLogService() { |
| // Add a service listener for log services. |
| try { |
| m_context.addServiceListener(this, "(objectClass=org.osgi.service.log.LogService)"); |
| } |
| catch (InvalidSyntaxException ex) { |
| // This will never happen since the filter is hard coded. |
| } |
| // Try to get an existing log service. |
| m_logRef = m_context.getServiceReference("org.osgi.service.log.LogService"); |
| // Get the service object if available and set it in the logger. |
| if (m_logRef != null) { |
| setLogger(m_context.getService(m_logRef)); |
| } |
| } |
| |
| /** |
| * This method implements the callback for the ServiceListener interface. |
| * It is public as a byproduct of implementing the interface and should |
| * not be called directly. This method tracks run-time changes to log |
| * service availability. If the log service being used by the framework's |
| * logging mechanism goes away, then this will try to find an alternative. |
| * If a higher ranking log service is registered, then this will switch |
| * to the higher ranking log service. |
| */ |
| public final synchronized void serviceChanged(ServiceEvent event) { |
| // If no logger is in use, then grab this one. |
| if ((event.getType() == ServiceEvent.REGISTERED) && (m_logRef == null)) { |
| m_logRef = event.getServiceReference(); |
| // Get the service object and set it in the logger. |
| setLogger(m_context.getService(m_logRef)); |
| } |
| // If a logger is in use, but this one has a higher ranking, then swap |
| // it for the existing logger. |
| else if ((event.getType() == ServiceEvent.REGISTERED) && (m_logRef != null)) { |
| ServiceReference ref = m_context.getServiceReference("org.osgi.service.log.LogService"); |
| if (!ref.equals(m_logRef)) { |
| m_context.ungetService(m_logRef); |
| m_logRef = ref; |
| setLogger(m_context.getService(m_logRef)); |
| } |
| } |
| // If the current logger is going away, release it and try to |
| // find another one. |
| else if ((event.getType() == ServiceEvent.UNREGISTERING) && m_logRef.equals(event.getServiceReference())) { |
| // Unget the service object. |
| m_context.ungetService(m_logRef); |
| // Try to get an existing log service. |
| m_logRef = m_context.getServiceReference("org.osgi.service.log.LogService"); |
| // Get the service object if available and set it in the logger. |
| if (m_logRef != null) { |
| setLogger(m_context.getService(m_logRef)); |
| } |
| else { |
| setLogger(null); |
| } |
| } |
| } |
| |
| /** |
| * This method sets the new log service object. It also caches the method to |
| * invoke. The service object and method are stored in array to optimistically |
| * eliminate the need to locking when logging. |
| */ |
| private void setLogger(Object logObj) { |
| if (logObj == null) { |
| m_logger = null; |
| } |
| else { |
| Class[] formalParams = { ServiceReference.class, Integer.TYPE, String.class, Throwable.class }; |
| try { |
| Method logMethod = logObj.getClass().getMethod("log", formalParams); |
| logMethod.setAccessible(true); |
| m_logger = new Object[] { logObj, logMethod }; |
| } |
| catch (NoSuchMethodException ex) { |
| System.err.println("Logger: " + ex); |
| m_logger = null; |
| } |
| } |
| } |
| } |