/*
* Copyright 2012-2017 the original author or authors.
*
* 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.springframework.boot.logging;
import java.util.Collections;
import java.util.EnumSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
/**
* Common abstraction over logging systems.
*
* @author Phillip Webb
* @author Dave Syer
* @author Andy Wilkinson
* @author Ben Hale
*/
public abstract class LoggingSystem {
/**
* A System property that can be used to indicate the {@link LoggingSystem} to use.
*/
public static final String SYSTEM_PROPERTY = LoggingSystem.class.getName();
/**
* The value of the {@link #SYSTEM_PROPERTY} that can be used to indicate that no
* {@link LoggingSystem} should be used.
*/
public static final String NONE = "none";
/**
* The name used for the root logger. LoggingSystem implementations should ensure that
* this is the name used to represent the root logger, regardless of the underlying
* implementation.
*/
public static final String ROOT_LOGGER_NAME = "ROOT";
private static final Map<String, String> SYSTEMS;
static {
Map<String, String> systems = new LinkedHashMap<>();
systems.put("ch.qos.logback.core.Appender",
"org.springframework.boot.logging.logback.LogbackLoggingSystem");
systems.put("org.apache.logging.log4j.core.impl.Log4jContextFactory",
"org.springframework.boot.logging.log4j2.Log4J2LoggingSystem");
systems.put("java.util.logging.LogManager",
"org.springframework.boot.logging.java.JavaLoggingSystem");
SYSTEMS = Collections.unmodifiableMap(systems);
}
/**
* Reset the logging system to be limit output. This method may be called before
* {@link #initialize(LoggingInitializationContext, String, LogFile)} to reduce
* logging noise until the system has been fully initialized.
*/
public abstract void beforeInitialize();
/**
* Fully initialize the logging system.
* @param initializationContext the logging initialization context
* @param configLocation a log configuration location or {@code null} if default
* initialization is required
* @param logFile the log output file that should be written or {@code null} for
* console only output
*/
public void initialize(LoggingInitializationContext initializationContext,
String configLocation, LogFile logFile) {
}
/**
* Clean up the logging system. The default implementation does nothing. Subclasses
* should override this method to perform any logging system-specific cleanup.
*/
public void cleanUp() {
}
/**
* Returns a {@link Runnable} that can handle shutdown of this logging system when the
* JVM exits. The default implementation returns {@code null}, indicating that no
* shutdown is required.
* @return the shutdown handler, or {@code null}
*/
public Runnable getShutdownHandler() {
return null;
}
/**
* Returns a set of the {@link LogLevel LogLevels} that are actually supported by the
* logging system.
* @return the supported levels
*/
public Set<LogLevel> getSupportedLogLevels() {
return EnumSet.allOf(LogLevel.class);
}
/**
* Sets the logging level for a given logger.
* @param loggerName the name of the logger to set ({@code null} can be used for the
* root logger).
* @param level the log level
*/
public void setLogLevel(String loggerName, LogLevel level) {
throw new UnsupportedOperationException("Unable to set log level");
}
/**
* Returns a collection of the current configuration for all a {@link LoggingSystem}'s
* loggers.
* @return the current configurations
* @since 1.5.0
*/
public List<LoggerConfiguration> getLoggerConfigurations() {
throw new UnsupportedOperationException("Unable to get logger configurations");
}
/**
* Returns the current configuration for a {@link LoggingSystem}'s logger.
* @param loggerName the name of the logger
* @return the current configuration
* @since 1.5.0
*/
public LoggerConfiguration getLoggerConfiguration(String loggerName) {
throw new UnsupportedOperationException("Unable to get logger configuration");
}
/**
* Detect and return the logging system in use. Supports Logback and Java Logging.
* @param classLoader the classloader
* @return The logging system
*/
public static LoggingSystem get(ClassLoader classLoader) {
String loggingSystem = System.getProperty(SYSTEM_PROPERTY);
if (StringUtils.hasLength(loggingSystem)) {
if (NONE.equals(loggingSystem)) {
return new NoOpLoggingSystem();
}
return get(classLoader, loggingSystem);
}
for (Map.Entry<String, String> entry : SYSTEMS.entrySet()) {
if (ClassUtils.isPresent(entry.getKey(), classLoader)) {
return get(classLoader, entry.getValue());
}
}
throw new IllegalStateException("No suitable logging system located");
}
private static LoggingSystem get(ClassLoader classLoader, String loggingSystemClass) {
try {
Class<?> systemClass = ClassUtils.forName(loggingSystemClass, classLoader);
return (LoggingSystem) systemClass.getConstructor(ClassLoader.class)
.newInstance(classLoader);
}
catch (Exception ex) {
throw new IllegalStateException(ex);
}
}
/**
* {@link LoggingSystem} that does nothing.
*/
static class NoOpLoggingSystem extends LoggingSystem {
@Override
public void beforeInitialize() {
}
@Override
public void setLogLevel(String loggerName, LogLevel level) {
}
@Override
public List<LoggerConfiguration> getLoggerConfigurations() {
return Collections.emptyList();
}
@Override
public LoggerConfiguration getLoggerConfiguration(String loggerName) {
return null;
}
}
}