001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache license, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the license for the specific language governing permissions and 015 * limitations under the license. 016 */ 017package org.apache.logging.log4j.web; 018 019import java.util.concurrent.locks.Lock; 020import java.util.concurrent.locks.ReentrantLock; 021import javax.servlet.ServletContext; 022 023import org.apache.logging.log4j.LogManager; 024import org.apache.logging.log4j.core.LoggerContext; 025import org.apache.logging.log4j.core.impl.ContextAnchor; 026 027/** 028 * Convenience methods for retrieving the {@link org.apache.logging.log4j.core.LoggerContext} associated with a 029 * particular ServletContext. These methods are most particularly useful for asynchronous servlets where the 030 * Thread Context ClassLoader (TCCL) is potentially different from the TCCL used by the 031 * Servlet container that bootstrapped Log4j. 032 * 033 * @since 2.0.1 034 */ 035public final class WebLoggerContextUtils { 036 private WebLoggerContextUtils() { 037 } 038 039 private static final Lock WEB_SUPPORT_LOOKUP = new ReentrantLock(); 040 041 /** 042 * Finds the main {@link org.apache.logging.log4j.core.LoggerContext} configured for the given ServletContext. 043 * 044 * @param servletContext the ServletContext to locate a LoggerContext for 045 * @return the LoggerContext for the given ServletContext 046 * @since 2.0.1 047 */ 048 public static LoggerContext getWebLoggerContext(final ServletContext servletContext) { 049 return (LoggerContext) servletContext.getAttribute(Log4jWebSupport.CONTEXT_ATTRIBUTE); 050 } 051 052 /** 053 * Finds the main {@link org.apache.logging.log4j.core.LoggerContext} configured for the given ServletContext. 054 * 055 * @param servletContext the ServletContext to locate a LoggerContext for 056 * @return the LoggerContext for the given ServletContext or {@code null} if none was set 057 * @throws java.lang.IllegalStateException if no LoggerContext could be found on the given ServletContext 058 * @since 2.0.1 059 */ 060 public static LoggerContext getRequiredWebLoggerContext(final ServletContext servletContext) { 061 final LoggerContext loggerContext = getWebLoggerContext(servletContext); 062 if (loggerContext == null) { 063 throw new IllegalStateException( 064 "No LoggerContext found in ServletContext attribute " + Log4jWebSupport.CONTEXT_ATTRIBUTE); 065 } 066 return loggerContext; 067 } 068 069 /** 070 * Finds or initializes the {@link org.apache.logging.log4j.web.Log4jWebLifeCycle} singleton for the given 071 * ServletContext. 072 * 073 * @param servletContext the ServletContext to get the Log4jWebLifeCycle for 074 * @return the Log4jWebLifeCycle for the given ServletContext 075 * @since 2.0.1 076 */ 077 public static Log4jWebLifeCycle getWebLifeCycle(final ServletContext servletContext) { 078 WEB_SUPPORT_LOOKUP.lock(); 079 try { 080 Log4jWebLifeCycle webLifeCycle = (Log4jWebLifeCycle) servletContext.getAttribute( 081 Log4jWebSupport.SUPPORT_ATTRIBUTE); 082 if (webLifeCycle == null) { 083 webLifeCycle = Log4jWebInitializerImpl.initialize(servletContext); 084 } 085 return webLifeCycle; 086 } finally { 087 WEB_SUPPORT_LOOKUP.unlock(); 088 } 089 } 090 091 /** 092 * Wraps a Runnable instance by setting its thread context {@link org.apache.logging.log4j.core.LoggerContext} 093 * before execution and clearing it after execution. 094 * 095 * @param servletContext the ServletContext to locate a LoggerContext for 096 * @param runnable the Runnable to wrap execution for 097 * @return a wrapped Runnable 098 * @since 2.0.1 099 */ 100 public static Runnable wrapExecutionContext(final ServletContext servletContext, final Runnable runnable) { 101 return new Runnable() { 102 @Override 103 public void run() { 104 final Log4jWebSupport webSupport = getWebLifeCycle(servletContext); 105 webSupport.setLoggerContext(); 106 try { 107 runnable.run(); 108 } finally { 109 webSupport.clearLoggerContext(); 110 } 111 } 112 }; 113 } 114 115 /** 116 * Gets the current {@link ServletContext} if it has already been assigned to a LoggerContext's external context. 117 * 118 * @return the current ServletContext attached to a LoggerContext or {@code null} if none could be found 119 * @since 2.1 120 */ 121 public static ServletContext getServletContext() { 122 org.apache.logging.log4j.spi.LoggerContext lc = ContextAnchor.THREAD_CONTEXT.get(); 123 if (lc == null) { 124 lc = LogManager.getContext(false); 125 } 126 return lc == null ? null : 127 lc.getExternalContext() instanceof ServletContext ? (ServletContext) lc.getExternalContext() : null; 128 } 129}