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Diffstat (limited to 'src/org/apache/commons/logging/impl/LogFactoryImpl.java')
| -rw-r--r-- | src/org/apache/commons/logging/impl/LogFactoryImpl.java | 1400 |
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diff --git a/src/org/apache/commons/logging/impl/LogFactoryImpl.java b/src/org/apache/commons/logging/impl/LogFactoryImpl.java deleted file mode 100644 index 8937b2f..0000000 --- a/src/org/apache/commons/logging/impl/LogFactoryImpl.java +++ /dev/null @@ -1,1400 +0,0 @@ -/* - * 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) $ - */ - -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()); - } - } - } -} |