| /* |
| * Copyright 2001-2004 The Apache Software Foundation. |
| * |
| * 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 org.apache.commons.logging.impl; |
| |
| |
| import java.lang.reflect.Constructor; |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.net.URL; |
| import java.util.Enumeration; |
| import java.util.Hashtable; |
| import java.util.Vector; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogConfigurationException; |
| import org.apache.commons.logging.LogFactory; |
| |
| |
| /** |
| * <p>Concrete subclass of {@link LogFactory} that implements the |
| * following algorithm to dynamically select a logging implementation |
| * class to instantiate a wrapper for.</p> |
| * <ul> |
| * <li>Use a factory configuration attribute named |
| * <code>org.apache.commons.logging.Log</code> to identify the |
| * requested implementation class.</li> |
| * <li>Use the <code>org.apache.commons.logging.Log</code> system property |
| * to identify the requested implementation class.</li> |
| * <li>If <em>Log4J</em> is available, return an instance of |
| * <code>org.apache.commons.logging.impl.Log4JLogger</code>.</li> |
| * <li>If <em>JDK 1.4 or later</em> is available, return an instance of |
| * <code>org.apache.commons.logging.impl.Jdk14Logger</code>.</li> |
| * <li>Otherwise, return an instance of |
| * <code>org.apache.commons.logging.impl.SimpleLog</code>.</li> |
| * </ul> |
| * |
| * <p>If the selected {@link Log} implementation class has a |
| * <code>setLogFactory()</code> method that accepts a {@link LogFactory} |
| * parameter, this method will be called on each newly created instance |
| * to identify the associated factory. This makes factory configuration |
| * attributes available to the Log instance, if it so desires.</p> |
| * |
| * <p>This factory will remember previously created <code>Log</code> instances |
| * for the same name, and will return them on repeated requests to the |
| * <code>getInstance()</code> method.</p> |
| * |
| * @author Rod Waldhoff |
| * @author Craig R. McClanahan |
| * @author Richard A. Sitze |
| * @author Brian Stansberry |
| * @version $Revision: 399224 $ $Date: 2006-05-03 10:25:54 +0100 (Wed, 03 May 2006) $ |
| * |
| * @deprecated Please use {@link java.net.URL#openConnection} instead. |
| * Please visit <a href="http://android-developers.blogspot.com/2011/09/androids-http-clients.html">this webpage</a> |
| * for further details. |
| */ |
| |
| @Deprecated |
| public class LogFactoryImpl extends LogFactory { |
| |
| |
| /** Log4JLogger class name */ |
| private static final String LOGGING_IMPL_LOG4J_LOGGER = "org.apache.commons.logging.impl.Log4JLogger"; |
| /** Jdk14Logger class name */ |
| private static final String LOGGING_IMPL_JDK14_LOGGER = "org.apache.commons.logging.impl.Jdk14Logger"; |
| /** Jdk13LumberjackLogger class name */ |
| private static final String LOGGING_IMPL_LUMBERJACK_LOGGER = "org.apache.commons.logging.impl.Jdk13LumberjackLogger"; |
| /** SimpleLog class name */ |
| private static final String LOGGING_IMPL_SIMPLE_LOGGER = "org.apache.commons.logging.impl.SimpleLog"; |
| |
| private static final String PKG_IMPL="org.apache.commons.logging.impl."; |
| private static final int PKG_LEN = PKG_IMPL.length(); |
| |
| // ----------------------------------------------------------- Constructors |
| |
| |
| |
| /** |
| * Public no-arguments constructor required by the lookup mechanism. |
| */ |
| public LogFactoryImpl() { |
| super(); |
| initDiagnostics(); // method on this object |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Instance created."); |
| } |
| } |
| |
| |
| // ----------------------------------------------------- Manifest Constants |
| |
| |
| /** |
| * The name (<code>org.apache.commons.logging.Log</code>) of the system |
| * property identifying our {@link Log} implementation class. |
| */ |
| public static final String LOG_PROPERTY = |
| "org.apache.commons.logging.Log"; |
| |
| |
| /** |
| * The deprecated system property used for backwards compatibility with |
| * old versions of JCL. |
| */ |
| protected static final String LOG_PROPERTY_OLD = |
| "org.apache.commons.logging.log"; |
| |
| /** |
| * The name (<code>org.apache.commons.logging.Log.allowFlawedContext</code>) |
| * of the system property which can be set true/false to |
| * determine system behaviour when a bad context-classloader is encountered. |
| * When set to false, a LogConfigurationException is thrown if |
| * LogFactoryImpl is loaded via a child classloader of the TCCL (this |
| * should never happen in sane systems). |
| * |
| * Default behaviour: true (tolerates bad context classloaders) |
| * |
| * See also method setAttribute. |
| */ |
| public static final String ALLOW_FLAWED_CONTEXT_PROPERTY = |
| "org.apache.commons.logging.Log.allowFlawedContext"; |
| |
| /** |
| * The name (<code>org.apache.commons.logging.Log.allowFlawedDiscovery</code>) |
| * of the system property which can be set true/false to |
| * determine system behaviour when a bad logging adapter class is |
| * encountered during logging discovery. When set to false, an |
| * exception will be thrown and the app will fail to start. When set |
| * to true, discovery will continue (though the user might end up |
| * with a different logging implementation than they expected). |
| * |
| * Default behaviour: true (tolerates bad logging adapters) |
| * |
| * See also method setAttribute. |
| */ |
| public static final String ALLOW_FLAWED_DISCOVERY_PROPERTY = |
| "org.apache.commons.logging.Log.allowFlawedDiscovery"; |
| |
| /** |
| * The name (<code>org.apache.commons.logging.Log.allowFlawedHierarchy</code>) |
| * of the system property which can be set true/false to |
| * determine system behaviour when a logging adapter class is |
| * encountered which has bound to the wrong Log class implementation. |
| * When set to false, an exception will be thrown and the app will fail |
| * to start. When set to true, discovery will continue (though the user |
| * might end up with a different logging implementation than they expected). |
| * |
| * Default behaviour: true (tolerates bad Log class hierarchy) |
| * |
| * See also method setAttribute. |
| */ |
| public static final String ALLOW_FLAWED_HIERARCHY_PROPERTY = |
| "org.apache.commons.logging.Log.allowFlawedHierarchy"; |
| |
| |
| /** |
| * The names of classes that will be tried (in order) as logging |
| * adapters. Each class is expected to implement the Log interface, |
| * and to throw NoClassDefFound or ExceptionInInitializerError when |
| * loaded if the underlying logging library is not available. Any |
| * other error indicates that the underlying logging library is available |
| * but broken/unusable for some reason. |
| */ |
| private static final String[] classesToDiscover = { |
| LOGGING_IMPL_LOG4J_LOGGER, |
| "org.apache.commons.logging.impl.Jdk14Logger", |
| "org.apache.commons.logging.impl.Jdk13LumberjackLogger", |
| "org.apache.commons.logging.impl.SimpleLog" |
| }; |
| |
| |
| // ----------------------------------------------------- Instance Variables |
| |
| /** |
| * Determines whether logging classes should be loaded using the thread-context |
| * classloader, or via the classloader that loaded this LogFactoryImpl class. |
| */ |
| private boolean useTCCL = true; |
| |
| /** |
| * The string prefixed to every message output by the logDiagnostic method. |
| */ |
| private String diagnosticPrefix; |
| |
| |
| /** |
| * Configuration attributes. |
| */ |
| protected Hashtable attributes = new Hashtable(); |
| |
| |
| /** |
| * The {@link org.apache.commons.logging.Log} instances that have |
| * already been created, keyed by logger name. |
| */ |
| protected Hashtable instances = new Hashtable(); |
| |
| |
| /** |
| * Name of the class implementing the Log interface. |
| */ |
| private String logClassName; |
| |
| |
| /** |
| * The one-argument constructor of the |
| * {@link org.apache.commons.logging.Log} |
| * implementation class that will be used to create new instances. |
| * This value is initialized by <code>getLogConstructor()</code>, |
| * and then returned repeatedly. |
| */ |
| protected Constructor logConstructor = null; |
| |
| |
| /** |
| * The signature of the Constructor to be used. |
| */ |
| protected Class logConstructorSignature[] = |
| { java.lang.String.class }; |
| |
| |
| /** |
| * The one-argument <code>setLogFactory</code> method of the selected |
| * {@link org.apache.commons.logging.Log} method, if it exists. |
| */ |
| protected Method logMethod = null; |
| |
| |
| /** |
| * The signature of the <code>setLogFactory</code> method to be used. |
| */ |
| protected Class logMethodSignature[] = |
| { LogFactory.class }; |
| |
| /** |
| * See getBaseClassLoader and initConfiguration. |
| */ |
| private boolean allowFlawedContext; |
| |
| /** |
| * See handleFlawedDiscovery and initConfiguration. |
| */ |
| private boolean allowFlawedDiscovery; |
| |
| /** |
| * See handleFlawedHierarchy and initConfiguration. |
| */ |
| private boolean allowFlawedHierarchy; |
| |
| // --------------------------------------------------------- Public Methods |
| |
| |
| /** |
| * Return the configuration attribute with the specified name (if any), |
| * or <code>null</code> if there is no such attribute. |
| * |
| * @param name Name of the attribute to return |
| */ |
| public Object getAttribute(String name) { |
| |
| return (attributes.get(name)); |
| |
| } |
| |
| |
| /** |
| * Return an array containing the names of all currently defined |
| * configuration attributes. If there are no such attributes, a zero |
| * length array is returned. |
| */ |
| public String[] getAttributeNames() { |
| |
| Vector names = new Vector(); |
| Enumeration keys = attributes.keys(); |
| while (keys.hasMoreElements()) { |
| names.addElement((String) keys.nextElement()); |
| } |
| String results[] = new String[names.size()]; |
| for (int i = 0; i < results.length; i++) { |
| results[i] = (String) names.elementAt(i); |
| } |
| return (results); |
| |
| } |
| |
| |
| /** |
| * Convenience method to derive a name from the specified class and |
| * call <code>getInstance(String)</code> with it. |
| * |
| * @param clazz Class for which a suitable Log name will be derived |
| * |
| * @exception LogConfigurationException if a suitable <code>Log</code> |
| * instance cannot be returned |
| */ |
| public Log getInstance(Class clazz) throws LogConfigurationException { |
| |
| return (getInstance(clazz.getName())); |
| |
| } |
| |
| |
| /** |
| * <p>Construct (if necessary) and return a <code>Log</code> instance, |
| * using the factory's current set of configuration attributes.</p> |
| * |
| * <p><strong>NOTE</strong> - Depending upon the implementation of |
| * the <code>LogFactory</code> you are using, the <code>Log</code> |
| * instance you are returned may or may not be local to the current |
| * application, and may or may not be returned again on a subsequent |
| * call with the same name argument.</p> |
| * |
| * @param name Logical name of the <code>Log</code> instance to be |
| * returned (the meaning of this name is only known to the underlying |
| * logging implementation that is being wrapped) |
| * |
| * @exception LogConfigurationException if a suitable <code>Log</code> |
| * instance cannot be returned |
| */ |
| public Log getInstance(String name) throws LogConfigurationException { |
| |
| Log instance = (Log) instances.get(name); |
| if (instance == null) { |
| instance = newInstance(name); |
| instances.put(name, instance); |
| } |
| return (instance); |
| |
| } |
| |
| |
| /** |
| * Release any internal references to previously created |
| * {@link org.apache.commons.logging.Log} |
| * instances returned by this factory. This is useful in environments |
| * like servlet containers, which implement application reloading by |
| * throwing away a ClassLoader. Dangling references to objects in that |
| * class loader would prevent garbage collection. |
| */ |
| public void release() { |
| |
| logDiagnostic("Releasing all known loggers"); |
| instances.clear(); |
| } |
| |
| |
| /** |
| * Remove any configuration attribute associated with the specified name. |
| * If there is no such attribute, no action is taken. |
| * |
| * @param name Name of the attribute to remove |
| */ |
| public void removeAttribute(String name) { |
| |
| attributes.remove(name); |
| |
| } |
| |
| |
| /** |
| * Set the configuration attribute with the specified name. Calling |
| * this with a <code>null</code> value is equivalent to calling |
| * <code>removeAttribute(name)</code>. |
| * <p> |
| * This method can be used to set logging configuration programmatically |
| * rather than via system properties. It can also be used in code running |
| * within a container (such as a webapp) to configure behaviour on a |
| * per-component level instead of globally as system properties would do. |
| * To use this method instead of a system property, call |
| * <pre> |
| * LogFactory.getFactory().setAttribute(...) |
| * </pre> |
| * This must be done before the first Log object is created; configuration |
| * changes after that point will be ignored. |
| * <p> |
| * This method is also called automatically if LogFactory detects a |
| * commons-logging.properties file; every entry in that file is set |
| * automatically as an attribute here. |
| * |
| * @param name Name of the attribute to set |
| * @param value Value of the attribute to set, or <code>null</code> |
| * to remove any setting for this attribute |
| */ |
| public void setAttribute(String name, Object value) { |
| |
| if (logConstructor != null) { |
| logDiagnostic("setAttribute: call too late; configuration already performed."); |
| } |
| |
| if (value == null) { |
| attributes.remove(name); |
| } else { |
| attributes.put(name, value); |
| } |
| |
| if (name.equals(TCCL_KEY)) { |
| useTCCL = Boolean.valueOf(value.toString()).booleanValue(); |
| } |
| |
| } |
| |
| |
| // ------------------------------------------------------ |
| // Static Methods |
| // |
| // These methods only defined as workarounds for a java 1.2 bug; |
| // theoretically none of these are needed. |
| // ------------------------------------------------------ |
| |
| /** |
| * Gets the context classloader. |
| * This method is a workaround for a java 1.2 compiler bug. |
| * @since 1.1 |
| */ |
| protected static ClassLoader getContextClassLoader() throws LogConfigurationException { |
| return LogFactory.getContextClassLoader(); |
| } |
| |
| |
| /** |
| * Workaround for bug in Java1.2; in theory this method is not needed. |
| * See LogFactory.isDiagnosticsEnabled. |
| */ |
| protected static boolean isDiagnosticsEnabled() { |
| return LogFactory.isDiagnosticsEnabled(); |
| } |
| |
| |
| /** |
| * Workaround for bug in Java1.2; in theory this method is not needed. |
| * See LogFactory.getClassLoader. |
| * @since 1.1 |
| */ |
| protected static ClassLoader getClassLoader(Class clazz) { |
| return LogFactory.getClassLoader(clazz); |
| } |
| |
| |
| // ------------------------------------------------------ Protected Methods |
| |
| /** |
| * Calculate and cache a string that uniquely identifies this instance, |
| * including which classloader the object was loaded from. |
| * <p> |
| * This string will later be prefixed to each "internal logging" message |
| * emitted, so that users can clearly see any unexpected behaviour. |
| * <p> |
| * Note that this method does not detect whether internal logging is |
| * enabled or not, nor where to output stuff if it is; that is all |
| * handled by the parent LogFactory class. This method just computes |
| * its own unique prefix for log messages. |
| */ |
| private void initDiagnostics() { |
| // It would be nice to include an identifier of the context classloader |
| // that this LogFactoryImpl object is responsible for. However that |
| // isn't possible as that information isn't available. It is possible |
| // to figure this out by looking at the logging from LogFactory to |
| // see the context & impl ids from when this object was instantiated, |
| // in order to link the impl id output as this object's prefix back to |
| // the context it is intended to manage. |
| // Note that this prefix should be kept consistent with that |
| // in LogFactory. |
| Class clazz = this.getClass(); |
| ClassLoader classLoader = getClassLoader(clazz); |
| String classLoaderName; |
| try { |
| if (classLoader == null) { |
| classLoaderName = "BOOTLOADER"; |
| } else { |
| classLoaderName = objectId(classLoader); |
| } |
| } catch(SecurityException e) { |
| classLoaderName = "UNKNOWN"; |
| } |
| diagnosticPrefix = "[LogFactoryImpl@" + System.identityHashCode(this) + " from " + classLoaderName + "] "; |
| } |
| |
| |
| /** |
| * Output a diagnostic message to a user-specified destination (if the |
| * user has enabled diagnostic logging). |
| * |
| * @param msg diagnostic message |
| * @since 1.1 |
| */ |
| protected void logDiagnostic(String msg) { |
| if (isDiagnosticsEnabled()) { |
| logRawDiagnostic(diagnosticPrefix + msg); |
| } |
| } |
| |
| /** |
| * Return the fully qualified Java classname of the {@link Log} |
| * implementation we will be using. |
| * |
| * @deprecated Never invoked by this class; subclasses should not assume |
| * it will be. |
| */ |
| protected String getLogClassName() { |
| |
| if (logClassName == null) { |
| discoverLogImplementation(getClass().getName()); |
| } |
| |
| return logClassName; |
| } |
| |
| |
| /** |
| * <p>Return the <code>Constructor</code> that can be called to instantiate |
| * new {@link org.apache.commons.logging.Log} instances.</p> |
| * |
| * <p><strong>IMPLEMENTATION NOTE</strong> - Race conditions caused by |
| * calling this method from more than one thread are ignored, because |
| * the same <code>Constructor</code> instance will ultimately be derived |
| * in all circumstances.</p> |
| * |
| * @exception LogConfigurationException if a suitable constructor |
| * cannot be returned |
| * |
| * @deprecated Never invoked by this class; subclasses should not assume |
| * it will be. |
| */ |
| protected Constructor getLogConstructor() |
| throws LogConfigurationException { |
| |
| // Return the previously identified Constructor (if any) |
| if (logConstructor == null) { |
| discoverLogImplementation(getClass().getName()); |
| } |
| |
| return logConstructor; |
| } |
| |
| |
| /** |
| * Is <em>JDK 1.3 with Lumberjack</em> logging available? |
| * |
| * @deprecated Never invoked by this class; subclasses should not assume |
| * it will be. |
| */ |
| protected boolean isJdk13LumberjackAvailable() { |
| return isLogLibraryAvailable( |
| "Jdk13Lumberjack", |
| "org.apache.commons.logging.impl.Jdk13LumberjackLogger"); |
| } |
| |
| |
| /** |
| * <p>Return <code>true</code> if <em>JDK 1.4 or later</em> logging |
| * is available. Also checks that the <code>Throwable</code> class |
| * supports <code>getStackTrace()</code>, which is required by |
| * Jdk14Logger.</p> |
| * |
| * @deprecated Never invoked by this class; subclasses should not assume |
| * it will be. |
| */ |
| protected boolean isJdk14Available() { |
| return isLogLibraryAvailable( |
| "Jdk14", |
| "org.apache.commons.logging.impl.Jdk14Logger"); |
| } |
| |
| |
| /** |
| * Is a <em>Log4J</em> implementation available? |
| * |
| * @deprecated Never invoked by this class; subclasses should not assume |
| * it will be. |
| */ |
| protected boolean isLog4JAvailable() { |
| return isLogLibraryAvailable( |
| "Log4J", |
| LOGGING_IMPL_LOG4J_LOGGER); |
| } |
| |
| |
| /** |
| * Create and return a new {@link org.apache.commons.logging.Log} |
| * instance for the specified name. |
| * |
| * @param name Name of the new logger |
| * |
| * @exception LogConfigurationException if a new instance cannot |
| * be created |
| */ |
| protected Log newInstance(String name) throws LogConfigurationException { |
| |
| Log instance = null; |
| try { |
| if (logConstructor == null) { |
| instance = discoverLogImplementation(name); |
| } |
| else { |
| Object params[] = { name }; |
| instance = (Log) logConstructor.newInstance(params); |
| } |
| |
| if (logMethod != null) { |
| Object params[] = { this }; |
| logMethod.invoke(instance, params); |
| } |
| |
| return (instance); |
| |
| } catch (LogConfigurationException lce) { |
| |
| // this type of exception means there was a problem in discovery |
| // and we've already output diagnostics about the issue, etc.; |
| // just pass it on |
| throw (LogConfigurationException) lce; |
| |
| } catch (InvocationTargetException e) { |
| // A problem occurred invoking the Constructor or Method |
| // previously discovered |
| Throwable c = e.getTargetException(); |
| if (c != null) { |
| throw new LogConfigurationException(c); |
| } else { |
| throw new LogConfigurationException(e); |
| } |
| } catch (Throwable t) { |
| // A problem occurred invoking the Constructor or Method |
| // previously discovered |
| throw new LogConfigurationException(t); |
| } |
| } |
| |
| |
| // ------------------------------------------------------ Private Methods |
| |
| /** |
| * Utility method to check whether a particular logging library is |
| * present and available for use. Note that this does <i>not</i> |
| * affect the future behaviour of this class. |
| */ |
| private boolean isLogLibraryAvailable(String name, String classname) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Checking for '" + name + "'."); |
| } |
| try { |
| Log log = createLogFromClass( |
| classname, |
| this.getClass().getName(), // dummy category |
| false); |
| |
| if (log == null) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Did not find '" + name + "'."); |
| } |
| return false; |
| } else { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Found '" + name + "'."); |
| } |
| return true; |
| } |
| } catch(LogConfigurationException e) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Logging system '" + name + "' is available but not useable."); |
| } |
| return false; |
| } |
| } |
| |
| /** |
| * Attempt to find an attribute (see method setAttribute) or a |
| * system property with the provided name and return its value. |
| * <p> |
| * The attributes associated with this object are checked before |
| * system properties in case someone has explicitly called setAttribute, |
| * or a configuration property has been set in a commons-logging.properties |
| * file. |
| * |
| * @return the value associated with the property, or null. |
| */ |
| private String getConfigurationValue(String property) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("[ENV] Trying to get configuration for item " + property); |
| } |
| |
| Object valueObj = getAttribute(property); |
| if (valueObj != null) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("[ENV] Found LogFactory attribute [" + valueObj + "] for " + property); |
| } |
| return valueObj.toString(); |
| } |
| |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("[ENV] No LogFactory attribute found for " + property); |
| } |
| |
| try { |
| String value = System.getProperty(property); |
| if (value != null) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("[ENV] Found system property [" + value + "] for " + property); |
| } |
| return value; |
| } |
| |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("[ENV] No system property found for property " + property); |
| } |
| } catch (SecurityException e) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("[ENV] Security prevented reading system property " + property); |
| } |
| } |
| |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("[ENV] No configuration defined for item " + property); |
| } |
| |
| return null; |
| } |
| |
| /** |
| * Get the setting for the user-configurable behaviour specified by key. |
| * If nothing has explicitly been set, then return dflt. |
| */ |
| private boolean getBooleanConfiguration(String key, boolean dflt) { |
| String val = getConfigurationValue(key); |
| if (val == null) |
| return dflt; |
| return Boolean.valueOf(val).booleanValue(); |
| } |
| |
| /** |
| * Initialize a number of variables that control the behaviour of this |
| * class and that can be tweaked by the user. This is done when the first |
| * logger is created, not in the constructor of this class, because we |
| * need to give the user a chance to call method setAttribute in order to |
| * configure this object. |
| */ |
| private void initConfiguration() { |
| allowFlawedContext = getBooleanConfiguration(ALLOW_FLAWED_CONTEXT_PROPERTY, true); |
| allowFlawedDiscovery = getBooleanConfiguration(ALLOW_FLAWED_DISCOVERY_PROPERTY, true); |
| allowFlawedHierarchy = getBooleanConfiguration(ALLOW_FLAWED_HIERARCHY_PROPERTY, true); |
| } |
| |
| |
| /** |
| * Attempts to create a Log instance for the given category name. |
| * Follows the discovery process described in the class javadoc. |
| * |
| * @param logCategory the name of the log category |
| * |
| * @throws LogConfigurationException if an error in discovery occurs, |
| * or if no adapter at all can be instantiated |
| */ |
| private Log discoverLogImplementation(String logCategory) |
| throws LogConfigurationException |
| { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Discovering a Log implementation..."); |
| } |
| |
| initConfiguration(); |
| |
| Log result = null; |
| |
| // See if the user specified the Log implementation to use |
| String specifiedLogClassName = findUserSpecifiedLogClassName(); |
| |
| if (specifiedLogClassName != null) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Attempting to load user-specified log class '" + |
| specifiedLogClassName + "'..."); |
| } |
| |
| result = createLogFromClass(specifiedLogClassName, |
| logCategory, |
| true); |
| if (result == null) { |
| StringBuffer messageBuffer = new StringBuffer("User-specified log class '"); |
| messageBuffer.append(specifiedLogClassName); |
| messageBuffer.append("' cannot be found or is not useable."); |
| |
| // Mistyping or misspelling names is a common fault. |
| // Construct a good error message, if we can |
| if (specifiedLogClassName != null) { |
| informUponSimilarName(messageBuffer, specifiedLogClassName, LOGGING_IMPL_LOG4J_LOGGER); |
| informUponSimilarName(messageBuffer, specifiedLogClassName, LOGGING_IMPL_JDK14_LOGGER); |
| informUponSimilarName(messageBuffer, specifiedLogClassName, LOGGING_IMPL_LUMBERJACK_LOGGER); |
| informUponSimilarName(messageBuffer, specifiedLogClassName, LOGGING_IMPL_SIMPLE_LOGGER); |
| } |
| throw new LogConfigurationException(messageBuffer.toString()); |
| } |
| |
| return result; |
| } |
| |
| // No user specified log; try to discover what's on the classpath |
| // |
| // Note that we deliberately loop here over classesToDiscover and |
| // expect method createLogFromClass to loop over the possible source |
| // classloaders. The effect is: |
| // for each discoverable log adapter |
| // for each possible classloader |
| // see if it works |
| // |
| // It appears reasonable at first glance to do the opposite: |
| // for each possible classloader |
| // for each discoverable log adapter |
| // see if it works |
| // |
| // The latter certainly has advantages for user-installable logging |
| // libraries such as log4j; in a webapp for example this code should |
| // first check whether the user has provided any of the possible |
| // logging libraries before looking in the parent classloader. |
| // Unfortunately, however, Jdk14Logger will always work in jvm>=1.4, |
| // and SimpleLog will always work in any JVM. So the loop would never |
| // ever look for logging libraries in the parent classpath. Yet many |
| // users would expect that putting log4j there would cause it to be |
| // detected (and this is the historical JCL behaviour). So we go with |
| // the first approach. A user that has bundled a specific logging lib |
| // in a webapp should use a commons-logging.properties file or a |
| // service file in META-INF to force use of that logging lib anyway, |
| // rather than relying on discovery. |
| |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic( |
| "No user-specified Log implementation; performing discovery" + |
| " using the standard supported logging implementations..."); |
| } |
| for(int i=0; (i<classesToDiscover.length) && (result == null); ++i) { |
| result = createLogFromClass(classesToDiscover[i], logCategory, true); |
| } |
| |
| if (result == null) { |
| throw new LogConfigurationException |
| ("No suitable Log implementation"); |
| } |
| |
| return result; |
| } |
| |
| |
| /** |
| * Appends message if the given name is similar to the candidate. |
| * @param messageBuffer <code>StringBuffer</code> the message should be appended to, |
| * not null |
| * @param name the (trimmed) name to be test against the candidate, not null |
| * @param candidate the candidate name (not null) |
| */ |
| private void informUponSimilarName(final StringBuffer messageBuffer, final String name, |
| final String candidate) { |
| if (name.equals(candidate)) { |
| // Don't suggest a name that is exactly the same as the one the |
| // user tried... |
| return; |
| } |
| |
| // If the user provides a name that is in the right package, and gets |
| // the first 5 characters of the adapter class right (ignoring case), |
| // then suggest the candidate adapter class name. |
| if (name.regionMatches(true, 0, candidate, 0, PKG_LEN + 5)) { |
| messageBuffer.append(" Did you mean '"); |
| messageBuffer.append(candidate); |
| messageBuffer.append("'?"); |
| } |
| } |
| |
| |
| /** |
| * Checks system properties and the attribute map for |
| * a Log implementation specified by the user under the |
| * property names {@link #LOG_PROPERTY} or {@link #LOG_PROPERTY_OLD}. |
| * |
| * @return classname specified by the user, or <code>null</code> |
| */ |
| private String findUserSpecifiedLogClassName() |
| { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Trying to get log class from attribute '" + LOG_PROPERTY + "'"); |
| } |
| String specifiedClass = (String) getAttribute(LOG_PROPERTY); |
| |
| if (specifiedClass == null) { // @deprecated |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Trying to get log class from attribute '" + |
| LOG_PROPERTY_OLD + "'"); |
| } |
| specifiedClass = (String) getAttribute(LOG_PROPERTY_OLD); |
| } |
| |
| if (specifiedClass == null) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Trying to get log class from system property '" + |
| LOG_PROPERTY + "'"); |
| } |
| try { |
| specifiedClass = System.getProperty(LOG_PROPERTY); |
| } catch (SecurityException e) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("No access allowed to system property '" + |
| LOG_PROPERTY + "' - " + e.getMessage()); |
| } |
| } |
| } |
| |
| if (specifiedClass == null) { // @deprecated |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Trying to get log class from system property '" + |
| LOG_PROPERTY_OLD + "'"); |
| } |
| try { |
| specifiedClass = System.getProperty(LOG_PROPERTY_OLD); |
| } catch (SecurityException e) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("No access allowed to system property '" + |
| LOG_PROPERTY_OLD + "' - " + e.getMessage()); |
| } |
| } |
| } |
| |
| // Remove any whitespace; it's never valid in a classname so its |
| // presence just means a user mistake. As we know what they meant, |
| // we may as well strip the spaces. |
| if (specifiedClass != null) { |
| specifiedClass = specifiedClass.trim(); |
| } |
| |
| return specifiedClass; |
| } |
| |
| |
| /** |
| * Attempts to load the given class, find a suitable constructor, |
| * and instantiate an instance of Log. |
| * |
| * @param logAdapterClassName classname of the Log implementation |
| * |
| * @param logCategory argument to pass to the Log implementation's |
| * constructor |
| * |
| * @param affectState <code>true</code> if this object's state should |
| * be affected by this method call, <code>false</code> otherwise. |
| * |
| * @return an instance of the given class, or null if the logging |
| * library associated with the specified adapter is not available. |
| * |
| * @throws LogConfigurationException if there was a serious error with |
| * configuration and the handleFlawedDiscovery method decided this |
| * problem was fatal. |
| */ |
| private Log createLogFromClass(String logAdapterClassName, |
| String logCategory, |
| boolean affectState) |
| throws LogConfigurationException { |
| |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Attempting to instantiate '" + logAdapterClassName + "'"); |
| } |
| |
| Object[] params = { logCategory }; |
| Log logAdapter = null; |
| Constructor constructor = null; |
| |
| Class logAdapterClass = null; |
| ClassLoader currentCL = getBaseClassLoader(); |
| |
| for(;;) { |
| // Loop through the classloader hierarchy trying to find |
| // a viable classloader. |
| logDiagnostic( |
| "Trying to load '" |
| + logAdapterClassName |
| + "' from classloader " |
| + objectId(currentCL)); |
| try { |
| if (isDiagnosticsEnabled()) { |
| // Show the location of the first occurrence of the .class file |
| // in the classpath. This is the location that ClassLoader.loadClass |
| // will load the class from -- unless the classloader is doing |
| // something weird. |
| URL url; |
| String resourceName = logAdapterClassName.replace('.', '/') + ".class"; |
| if (currentCL != null) { |
| url = currentCL.getResource(resourceName ); |
| } else { |
| url = ClassLoader.getSystemResource(resourceName + ".class"); |
| } |
| |
| if (url == null) { |
| logDiagnostic("Class '" + logAdapterClassName + "' [" + resourceName + "] cannot be found."); |
| } else { |
| logDiagnostic("Class '" + logAdapterClassName + "' was found at '" + url + "'"); |
| } |
| } |
| |
| Class c = null; |
| try { |
| c = Class.forName(logAdapterClassName, true, currentCL); |
| } catch (ClassNotFoundException originalClassNotFoundException) { |
| // The current classloader was unable to find the log adapter |
| // in this or any ancestor classloader. There's no point in |
| // trying higher up in the hierarchy in this case.. |
| String msg = "" + originalClassNotFoundException.getMessage(); |
| logDiagnostic( |
| "The log adapter '" |
| + logAdapterClassName |
| + "' is not available via classloader " |
| + objectId(currentCL) |
| + ": " |
| + msg.trim()); |
| try { |
| // Try the class classloader. |
| // This may work in cases where the TCCL |
| // does not contain the code executed or JCL. |
| // This behaviour indicates that the application |
| // classloading strategy is not consistent with the |
| // Java 1.2 classloading guidelines but JCL can |
| // and so should handle this case. |
| c = Class.forName(logAdapterClassName); |
| } catch (ClassNotFoundException secondaryClassNotFoundException) { |
| // no point continuing: this adapter isn't available |
| msg = "" + secondaryClassNotFoundException.getMessage(); |
| logDiagnostic( |
| "The log adapter '" |
| + logAdapterClassName |
| + "' is not available via the LogFactoryImpl class classloader: " |
| + msg.trim()); |
| break; |
| } |
| } |
| |
| constructor = c.getConstructor(logConstructorSignature); |
| Object o = constructor.newInstance(params); |
| |
| // Note that we do this test after trying to create an instance |
| // [rather than testing Log.class.isAssignableFrom(c)] so that |
| // we don't complain about Log hierarchy problems when the |
| // adapter couldn't be instantiated anyway. |
| if (o instanceof Log) { |
| logAdapterClass = c; |
| logAdapter = (Log) o; |
| break; |
| } |
| |
| // Oops, we have a potential problem here. An adapter class |
| // has been found and its underlying lib is present too, but |
| // there are multiple Log interface classes available making it |
| // impossible to cast to the type the caller wanted. We |
| // certainly can't use this logger, but we need to know whether |
| // to keep on discovering or terminate now. |
| // |
| // The handleFlawedHierarchy method will throw |
| // LogConfigurationException if it regards this problem as |
| // fatal, and just return if not. |
| handleFlawedHierarchy(currentCL, c); |
| } catch (NoClassDefFoundError e) { |
| // We were able to load the adapter but it had references to |
| // other classes that could not be found. This simply means that |
| // the underlying logger library is not present in this or any |
| // ancestor classloader. There's no point in trying higher up |
| // in the hierarchy in this case.. |
| String msg = "" + e.getMessage(); |
| logDiagnostic( |
| "The log adapter '" |
| + logAdapterClassName |
| + "' is missing dependencies when loaded via classloader " |
| + objectId(currentCL) |
| + ": " |
| + msg.trim()); |
| break; |
| } catch (ExceptionInInitializerError e) { |
| // A static initializer block or the initializer code associated |
| // with a static variable on the log adapter class has thrown |
| // an exception. |
| // |
| // We treat this as meaning the adapter's underlying logging |
| // library could not be found. |
| String msg = "" + e.getMessage(); |
| logDiagnostic( |
| "The log adapter '" |
| + logAdapterClassName |
| + "' is unable to initialize itself when loaded via classloader " |
| + objectId(currentCL) |
| + ": " |
| + msg.trim()); |
| break; |
| } catch(LogConfigurationException e) { |
| // call to handleFlawedHierarchy above must have thrown |
| // a LogConfigurationException, so just throw it on |
| throw e; |
| } catch(Throwable t) { |
| // handleFlawedDiscovery will determine whether this is a fatal |
| // problem or not. If it is fatal, then a LogConfigurationException |
| // will be thrown. |
| handleFlawedDiscovery(logAdapterClassName, currentCL, t); |
| } |
| |
| if (currentCL == null) { |
| break; |
| } |
| |
| // try the parent classloader |
| currentCL = currentCL.getParent(); |
| } |
| |
| if ((logAdapter != null) && affectState) { |
| // We've succeeded, so set instance fields |
| this.logClassName = logAdapterClassName; |
| this.logConstructor = constructor; |
| |
| // Identify the <code>setLogFactory</code> method (if there is one) |
| try { |
| this.logMethod = logAdapterClass.getMethod("setLogFactory", |
| logMethodSignature); |
| logDiagnostic("Found method setLogFactory(LogFactory) in '" |
| + logAdapterClassName + "'"); |
| } catch (Throwable t) { |
| this.logMethod = null; |
| logDiagnostic( |
| "[INFO] '" + logAdapterClassName |
| + "' from classloader " + objectId(currentCL) |
| + " does not declare optional method " |
| + "setLogFactory(LogFactory)"); |
| } |
| |
| logDiagnostic( |
| "Log adapter '" + logAdapterClassName |
| + "' from classloader " + objectId(logAdapterClass.getClassLoader()) |
| + " has been selected for use."); |
| } |
| |
| return logAdapter; |
| } |
| |
| |
| /** |
| * Return the classloader from which we should try to load the logging |
| * adapter classes. |
| * <p> |
| * This method usually returns the context classloader. However if it |
| * is discovered that the classloader which loaded this class is a child |
| * of the context classloader <i>and</i> the allowFlawedContext option |
| * has been set then the classloader which loaded this class is returned |
| * instead. |
| * <p> |
| * The only time when the classloader which loaded this class is a |
| * descendant (rather than the same as or an ancestor of the context |
| * classloader) is when an app has created custom classloaders but |
| * failed to correctly set the context classloader. This is a bug in |
| * the calling application; however we provide the option for JCL to |
| * simply generate a warning rather than fail outright. |
| * |
| */ |
| private ClassLoader getBaseClassLoader() throws LogConfigurationException { |
| ClassLoader thisClassLoader = getClassLoader(LogFactoryImpl.class); |
| |
| if (useTCCL == false) { |
| return thisClassLoader; |
| } |
| |
| ClassLoader contextClassLoader = getContextClassLoader(); |
| |
| ClassLoader baseClassLoader = getLowestClassLoader( |
| contextClassLoader, thisClassLoader); |
| |
| if (baseClassLoader == null) { |
| // The two classloaders are not part of a parent child relationship. |
| // In some classloading setups (e.g. JBoss with its |
| // UnifiedLoaderRepository) this can still work, so if user hasn't |
| // forbidden it, just return the contextClassLoader. |
| if (allowFlawedContext) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic( |
| "[WARNING] the context classloader is not part of a" |
| + " parent-child relationship with the classloader that" |
| + " loaded LogFactoryImpl."); |
| } |
| // If contextClassLoader were null, getLowestClassLoader() would |
| // have returned thisClassLoader. The fact we are here means |
| // contextClassLoader is not null, so we can just return it. |
| return contextClassLoader; |
| } |
| else { |
| throw new LogConfigurationException( |
| "Bad classloader hierarchy; LogFactoryImpl was loaded via" |
| + " a classloader that is not related to the current context" |
| + " classloader."); |
| } |
| } |
| |
| if (baseClassLoader != contextClassLoader) { |
| // We really should just use the contextClassLoader as the starting |
| // point for scanning for log adapter classes. However it is expected |
| // that there are a number of broken systems out there which create |
| // custom classloaders but fail to set the context classloader so |
| // we handle those flawed systems anyway. |
| if (allowFlawedContext) { |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic( |
| "Warning: the context classloader is an ancestor of the" |
| + " classloader that loaded LogFactoryImpl; it should be" |
| + " the same or a descendant. The application using" |
| + " commons-logging should ensure the context classloader" |
| + " is used correctly."); |
| } |
| } else { |
| throw new LogConfigurationException( |
| "Bad classloader hierarchy; LogFactoryImpl was loaded via" |
| + " a classloader that is not related to the current context" |
| + " classloader."); |
| } |
| } |
| |
| return baseClassLoader; |
| } |
| |
| /** |
| * Given two related classloaders, return the one which is a child of |
| * the other. |
| * <p> |
| * @param c1 is a classloader (including the null classloader) |
| * @param c2 is a classloader (including the null classloader) |
| * |
| * @return c1 if it has c2 as an ancestor, c2 if it has c1 as an ancestor, |
| * and null if neither is an ancestor of the other. |
| */ |
| private ClassLoader getLowestClassLoader(ClassLoader c1, ClassLoader c2) { |
| // TODO: use AccessController when dealing with classloaders here |
| |
| if (c1 == null) |
| return c2; |
| |
| if (c2 == null) |
| return c1; |
| |
| ClassLoader current; |
| |
| // scan c1's ancestors to find c2 |
| current = c1; |
| while (current != null) { |
| if (current == c2) |
| return c1; |
| current = current.getParent(); |
| } |
| |
| // scan c2's ancestors to find c1 |
| current = c2; |
| while (current != null) { |
| if (current == c1) |
| return c2; |
| current = current.getParent(); |
| } |
| |
| return null; |
| } |
| |
| /** |
| * Generates an internal diagnostic logging of the discovery failure and |
| * then throws a <code>LogConfigurationException</code> that wraps |
| * the passed <code>Throwable</code>. |
| * |
| * @param logAdapterClassName is the class name of the Log implementation |
| * that could not be instantiated. Cannot be <code>null</code>. |
| * |
| * @param classLoader is the classloader that we were trying to load the |
| * logAdapterClassName from when the exception occurred. |
| * |
| * @param discoveryFlaw is the Throwable created by the classloader |
| * |
| * @throws LogConfigurationException ALWAYS |
| */ |
| private void handleFlawedDiscovery(String logAdapterClassName, |
| ClassLoader classLoader, |
| Throwable discoveryFlaw) { |
| |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic("Could not instantiate Log '" |
| + logAdapterClassName + "' -- " |
| + discoveryFlaw.getClass().getName() + ": " |
| + discoveryFlaw.getLocalizedMessage()); |
| } |
| |
| if (!allowFlawedDiscovery) { |
| throw new LogConfigurationException(discoveryFlaw); |
| } |
| } |
| |
| |
| /** |
| * Report a problem loading the log adapter, then either return |
| * (if the situation is considered recoverable) or throw a |
| * LogConfigurationException. |
| * <p> |
| * There are two possible reasons why we successfully loaded the |
| * specified log adapter class then failed to cast it to a Log object: |
| * <ol> |
| * <li>the specific class just doesn't implement the Log interface |
| * (user screwed up), or |
| * <li> the specified class has bound to a Log class loaded by some other |
| * classloader; Log@classloaderX cannot be cast to Log@classloaderY. |
| * </ol> |
| * <p> |
| * Here we try to figure out which case has occurred so we can give the |
| * user some reasonable feedback. |
| * |
| * @param badClassLoader is the classloader we loaded the problem class from, |
| * ie it is equivalent to badClass.getClassLoader(). |
| * |
| * @param badClass is a Class object with the desired name, but which |
| * does not implement Log correctly. |
| * |
| * @throws LogConfigurationException when the situation |
| * should not be recovered from. |
| */ |
| private void handleFlawedHierarchy(ClassLoader badClassLoader, Class badClass) |
| throws LogConfigurationException { |
| |
| boolean implementsLog = false; |
| String logInterfaceName = Log.class.getName(); |
| Class interfaces[] = badClass.getInterfaces(); |
| for (int i = 0; i < interfaces.length; i++) { |
| if (logInterfaceName.equals(interfaces[i].getName())) { |
| implementsLog = true; |
| break; |
| } |
| } |
| |
| if (implementsLog) { |
| // the class does implement an interface called Log, but |
| // it is in the wrong classloader |
| if (isDiagnosticsEnabled()) { |
| try { |
| ClassLoader logInterfaceClassLoader = getClassLoader(Log.class); |
| logDiagnostic( |
| "Class '" + badClass.getName() |
| + "' was found in classloader " |
| + objectId(badClassLoader) |
| + ". It is bound to a Log interface which is not" |
| + " the one loaded from classloader " |
| + objectId(logInterfaceClassLoader)); |
| } catch (Throwable t) { |
| logDiagnostic( |
| "Error while trying to output diagnostics about" |
| + " bad class '" + badClass + "'"); |
| } |
| } |
| |
| if (!allowFlawedHierarchy) { |
| StringBuffer msg = new StringBuffer(); |
| msg.append("Terminating logging for this context "); |
| msg.append("due to bad log hierarchy. "); |
| msg.append("You have more than one version of '"); |
| msg.append(Log.class.getName()); |
| msg.append("' visible."); |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic(msg.toString()); |
| } |
| throw new LogConfigurationException(msg.toString()); |
| } |
| |
| if (isDiagnosticsEnabled()) { |
| StringBuffer msg = new StringBuffer(); |
| msg.append("Warning: bad log hierarchy. "); |
| msg.append("You have more than one version of '"); |
| msg.append(Log.class.getName()); |
| msg.append("' visible."); |
| logDiagnostic(msg.toString()); |
| } |
| } else { |
| // this is just a bad adapter class |
| if (!allowFlawedDiscovery) { |
| StringBuffer msg = new StringBuffer(); |
| msg.append("Terminating logging for this context. "); |
| msg.append("Log class '"); |
| msg.append(badClass.getName()); |
| msg.append("' does not implement the Log interface."); |
| if (isDiagnosticsEnabled()) { |
| logDiagnostic(msg.toString()); |
| } |
| |
| throw new LogConfigurationException(msg.toString()); |
| } |
| |
| if (isDiagnosticsEnabled()) { |
| StringBuffer msg = new StringBuffer(); |
| msg.append("[WARNING] Log class '"); |
| msg.append(badClass.getName()); |
| msg.append("' does not implement the Log interface."); |
| logDiagnostic(msg.toString()); |
| } |
| } |
| } |
| } |
