001/* 002 * Copyright 2002-2019 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.core.log; 018 019import java.util.ArrayList; 020import java.util.Collections; 021import java.util.List; 022 023import org.apache.commons.logging.Log; 024import org.apache.commons.logging.LogFactory; 025 026/** 027 * Factory for common {@link Log} delegates with Spring's logging conventions. 028 * 029 * <p>Mainly for internal use within the framework with Apache Commons Logging, 030 * typically in the form of the {@code spring-jcl} bridge but also compatible 031 * with other Commons Logging bridges. 032 * 033 * @author Rossen Stoyanchev 034 * @author Juergen Hoeller 035 * @since 5.1 036 * @see org.apache.commons.logging.LogFactory 037 */ 038public final class LogDelegateFactory { 039 040 private LogDelegateFactory() { 041 } 042 043 044 /** 045 * Create a composite logger that delegates to a primary or falls back on a 046 * secondary logger if logging for the primary logger is not enabled. 047 * <p>This may be used for fallback logging from lower-level packages that 048 * logically should log together with some higher-level package but the two 049 * don't happen to share a suitable parent package (e.g. logging for the web 050 * and lower-level http and codec packages). For such cases the primary 051 * (class-based) logger can be wrapped with a shared fallback logger. 052 * @param primaryLogger primary logger to try first 053 * @param secondaryLogger secondary logger 054 * @param tertiaryLoggers optional vararg of further fallback loggers 055 * @return the resulting composite logger for the related categories 056 */ 057 public static Log getCompositeLog(Log primaryLogger, Log secondaryLogger, Log... tertiaryLoggers) { 058 List<Log> loggers = new ArrayList<>(2 + tertiaryLoggers.length); 059 loggers.add(primaryLogger); 060 loggers.add(secondaryLogger); 061 Collections.addAll(loggers, tertiaryLoggers); 062 return new CompositeLog(loggers); 063 } 064 065 /** 066 * Create a "hidden" logger whose name is intentionally prefixed with "_" 067 * because its output is either too verbose or otherwise deemed as optional 068 * or unnecessary to see at any log level by default under the normal package 069 * based log hierarchy. 070 * @param clazz the class for which to create a logger 071 * @return a logger for the hidden category ("_" + fully-qualified class name) 072 */ 073 public static Log getHiddenLog(Class<?> clazz) { 074 return LogFactory.getLog("_" + clazz.getName()); 075 } 076 077}