/*
 * Copyright 2002-2018 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.core.log;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

Factory for common Log delegates with Spring's logging conventions. 
Mainly for internal use within the framework with Apache Commons Logging, typically in the form of the spring-jcl bridge but also compatible with other Commons Logging bridges. 
Author:
Rossen Stoyanchev, Juergen Hoeller
See Also:
LogFactory
Since:
5.1/**
 * Factory for common {@link Log} delegates with Spring's logging conventions.
 *
 * <p>Mainly for internal use within the framework with Apache Commons Logging,
 * typically in the form of the {@code spring-jcl} bridge but also compatible
 * with other Commons Logging bridges.
 *
 * @author Rossen Stoyanchev
 * @author Juergen Hoeller
 * @since 5.1
 * @see org.apache.commons.logging.LogFactory
 */
public final class LogDelegateFactory {

	private LogDelegateFactory() {
	}


	
Create a composite logger that delegates to a primary or falls back on a
secondary logger if logging for the primary logger is not enabled.
This may be used for fallback logging from lower level packages that
logically should log together with some higher level package but the two
don't happen to share a suitable parent package (e.g. logging for the web
and lower level http and codec packages). For such cases the primary,
class-based logger can be wrapped with a shared fallback logger.
Params:
primaryLogger – primary logger to try first
secondaryLogger – secondary logger
tertiaryLoggers – optionally, more fallback loggers
Returns:
the resulting logger to use/**
	 * Create a composite logger that delegates to a primary or falls back on a
	 * secondary logger if logging for the primary logger is not enabled.
	 * <p>This may be used for fallback logging from lower level packages that
	 * logically should log together with some higher level package but the two
	 * don't happen to share a suitable parent package (e.g. logging for the web
	 * and lower level http and codec packages). For such cases the primary,
	 * class-based logger can be wrapped with a shared fallback logger.
	 * @param primaryLogger primary logger to try first
	 * @param secondaryLogger secondary logger
	 * @param tertiaryLoggers optionally, more fallback loggers
	 * @return the resulting logger to use
	 */
	public static Log getCompositeLog(Log primaryLogger, Log secondaryLogger, Log... tertiaryLoggers) {
		List<Log> loggers = new ArrayList<>(2 + tertiaryLoggers.length);
		loggers.add(primaryLogger);
		loggers.add(secondaryLogger);
		Collections.addAll(loggers, tertiaryLoggers);
		return new CompositeLog(loggers);
	}

	
Create a "hidden" logger whose name is intentionally prefixed with "_"
because its output is either too verbose or otherwise deemed as optional
or unnecessary to see at any log level by default under the normal package
based log hierarchy.
Params:
clazz – the class for which to create a logger
Returns:
the created logger/**
	 * Create a "hidden" logger whose name is intentionally prefixed with "_"
	 * because its output is either too verbose or otherwise deemed as optional
	 * or unnecessary to see at any log level by default under the normal package
	 * based log hierarchy.
	 * @param clazz the class for which to create a logger
	 * @return the created logger
	 */
	public static Log getHiddenLog(Class<?> clazz) {
		return LogFactory.getLog("_" + clazz.getName());
	}

}