org.slf4j.LoggerFactory Maven / Gradle / Ivy
/*
* Copyright (c) 2004-2008 QOS.ch
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package org.slf4j;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.List;
import org.slf4j.helpers.NOPLoggerFactory;
import org.slf4j.helpers.SubstituteLoggerFactory;
import org.slf4j.helpers.Util;
import org.slf4j.impl.StaticLoggerBinder;
/**
* The LoggerFactory is a utility class producing Loggers for
* various logging APIs, most notably for log4j, logback and JDK 1.4 logging.
* Other implementations such as {@link org.slf4j.impl.NOPLogger NOPLogger} and
* {@link org.slf4j.impl.SimpleLogger SimpleLogger} are also supported.
*
*
* LoggerFactory is essentially a wrapper around an
* {@link ILoggerFactory} instance bound with LoggerFactory at
* compile time.
*
*
* Please note that all methods in LoggerFactory are static.
*
* @author Ceki Gülcü
* @author Robert Elliot
*/
public final class LoggerFactory {
static final String CODES_PREFIX = "http://www.slf4j.org/codes.html";
static final String NO_STATICLOGGERBINDER_URL = CODES_PREFIX+"#StaticLoggerBinder";
static final String MULTIPLE_BINDINGS_URL = CODES_PREFIX+"#multiple_bindings";
static final String NULL_LF_URL = CODES_PREFIX+"#null_LF";
static final String VERSION_MISMATCH = CODES_PREFIX+"#version_mismatch";
static final String SUBSTITUTE_LOGGER_URL = CODES_PREFIX+"#substituteLogger";
static final String UNSUCCESSFUL_INIT_URL = CODES_PREFIX+"#unsuccessfulInit";
static final String UNSUCCESSFUL_INIT_MSG = "org.slf4j.LoggerFactory could not be successfully initialized. See also "
+ UNSUCCESSFUL_INIT_URL;
static final int UNINITIALIZED = 0;
static final int ONGOING_INITILIZATION = 1;
static final int FAILED_INITILIZATION = 2;
static final int SUCCESSFUL_INITILIZATION = 3;
static final int NOP_FALLBACK_INITILIZATION = 4;
static int INITIALIZATION_STATE = UNINITIALIZED;
static SubstituteLoggerFactory TEMP_FACTORY = new SubstituteLoggerFactory();
static NOPLoggerFactory NOP_FALLBACK_FACTORY = new NOPLoggerFactory();
/**
* It is LoggerFactory's responsibility to track version changes and manage
* the compatibility list.
*
*
* It is assumed that all versions in the 1.6 are mutually compatible.
* */
static private final String[] API_COMPATIBILITY_LIST = new String[] { "1.6" };
// private constructor prevents instantiation
private LoggerFactory() {
}
/**
* Force LoggerFactory to consider itself uninitialized.
*
*
* This method is intended to be called by classes (in the same package) for
* testing purposes. This method is internal. It can be modified, renamed or
* removed at any time without notice.
*
*
* You are strongly discouraged from calling this method in production code.
*/
static void reset() {
INITIALIZATION_STATE = UNINITIALIZED;
TEMP_FACTORY = new SubstituteLoggerFactory();
}
private final static void performInitialization() {
singleImplementationSanityCheck();
bind();
if (INITIALIZATION_STATE == SUCCESSFUL_INITILIZATION) {
versionSanityCheck();
}
}
private final static void bind() {
try {
// the next line does the binding
StaticLoggerBinder.getSingleton();
INITIALIZATION_STATE = SUCCESSFUL_INITILIZATION;
emitSubstituteLoggerWarning();
} catch (NoClassDefFoundError ncde) {
String msg = ncde.getMessage();
if (msg != null && msg.indexOf("org/slf4j/impl/StaticLoggerBinder") != -1) {
INITIALIZATION_STATE = NOP_FALLBACK_INITILIZATION;
Util
.report("Failed to load class \"org.slf4j.impl.StaticLoggerBinder\".");
Util.report("Defaulting to no-operation (NOP) logger implementation");
Util.report("See " + NO_STATICLOGGERBINDER_URL
+ " for further details.");
} else {
failedBinding(ncde);
throw ncde;
}
} catch(java.lang.NoSuchMethodError nsme) {
String msg = nsme.getMessage();
if (msg != null && msg.indexOf("org.slf4j.impl.StaticLoggerBinder.getSingleton()") != -1) {
INITIALIZATION_STATE = FAILED_INITILIZATION;
Util.report("slf4j-api 1.6.x (or later) is incompatible with this binding.");
Util.report("Your binding is version 1.5.5 or earlier.");
Util.report("Upgrade your binding to version 1.6.x. or 2.0.x");
}
throw nsme;
} catch (Exception e) {
failedBinding(e);
throw new IllegalStateException("Unexpected initialization failure", e);
}
}
static void failedBinding(Throwable t) {
INITIALIZATION_STATE = FAILED_INITILIZATION;
Util.report("Failed to instantiate SLF4J LoggerFactory", t);
}
private final static void emitSubstituteLoggerWarning() {
List loggerNameList = TEMP_FACTORY.getLoggerNameList();
if (loggerNameList.size() == 0) {
return;
}
Util
.report("The following loggers will not work becasue they were created");
Util
.report("during the default configuration phase of the underlying logging system.");
Util.report("See also " + SUBSTITUTE_LOGGER_URL);
for (int i = 0; i < loggerNameList.size(); i++) {
String loggerName = (String) loggerNameList.get(i);
Util.report(loggerName);
}
}
private final static void versionSanityCheck() {
try {
String requested = StaticLoggerBinder.REQUESTED_API_VERSION;
boolean match = false;
for (int i = 0; i < API_COMPATIBILITY_LIST.length; i++) {
if (requested.startsWith(API_COMPATIBILITY_LIST[i])) {
match = true;
}
}
if (!match) {
Util.report("The requested version " + requested
+ " by your slf4j binding is not compatible with "
+ Arrays.asList(API_COMPATIBILITY_LIST).toString());
Util.report("See " + VERSION_MISMATCH + " for further details.");
}
} catch (java.lang.NoSuchFieldError nsfe) {
// given our large user base and SLF4J's commitment to backward
// compatibility, we cannot cry here. Only for implementations
// which willingly declare a REQUESTED_API_VERSION field do we
// emit compatibility warnings.
} catch (Throwable e) {
// we should never reach here
Util.report("Unexpected problem occured during version sanity check", e);
}
}
// We need to use the name of the StaticLoggerBinder class, we can't reference
// the class itseld.
private static String STATIC_LOGGER_BINDER_PATH = "org/slf4j/impl/StaticLoggerBinder.class";
private static void singleImplementationSanityCheck() {
try {
ClassLoader loggerFactoryClassLoader = LoggerFactory.class
.getClassLoader();
Enumeration paths;
if (loggerFactoryClassLoader == null) {
paths = ClassLoader.getSystemResources(STATIC_LOGGER_BINDER_PATH);
} else {
paths = loggerFactoryClassLoader
.getResources(STATIC_LOGGER_BINDER_PATH);
}
List implementationList = new ArrayList();
while (paths.hasMoreElements()) {
URL path = (URL) paths.nextElement();
implementationList.add(path);
}
if (implementationList.size() > 1) {
Util.report("Class path contains multiple SLF4J bindings.");
for (int i = 0; i < implementationList.size(); i++) {
Util.report("Found binding in [" + implementationList.get(i) + "]");
}
Util.report("See " + MULTIPLE_BINDINGS_URL + " for an explanation.");
}
} catch (IOException ioe) {
Util.report("Error getting resources from path", ioe);
}
}
/**
* Return a logger named according to the name parameter using the statically
* bound {@link ILoggerFactory} instance.
*
* @param name
* The name of the logger.
* @return logger
*/
public static Logger getLogger(String name) {
ILoggerFactory iLoggerFactory = getILoggerFactory();
return iLoggerFactory.getLogger(name);
}
/**
* Return a logger named corresponding to the class passed as parameter, using
* the statically bound {@link ILoggerFactory} instance.
*
* @param clazz
* the returned logger will be named after clazz
* @return logger
*/
public static Logger getLogger(Class clazz) {
return getLogger(clazz.getName());
}
/**
* Return the {@link ILoggerFactory} instance in use.
*
*
* ILoggerFactory instance is bound with this class at compile time.
*
* @return the ILoggerFactory instance in use
*/
public static ILoggerFactory getILoggerFactory() {
if (INITIALIZATION_STATE == UNINITIALIZED) {
INITIALIZATION_STATE = ONGOING_INITILIZATION;
performInitialization();
}
switch (INITIALIZATION_STATE) {
case SUCCESSFUL_INITILIZATION:
return StaticLoggerBinder.getSingleton().getLoggerFactory();
case NOP_FALLBACK_INITILIZATION:
return NOP_FALLBACK_FACTORY;
case FAILED_INITILIZATION:
throw new IllegalStateException(UNSUCCESSFUL_INIT_MSG);
case ONGOING_INITILIZATION:
// support re-entrant behavior.
// See also http://bugzilla.slf4j.org/show_bug.cgi?id=106
return TEMP_FACTORY;
}
throw new IllegalStateException("Unreachable code");
}
}