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 */ 017 package org.apache.logging.log4j.web; 018 019 import java.util.concurrent.locks.Lock; 020 import java.util.concurrent.locks.ReentrantLock; 021 import javax.servlet.ServletContext; 022 023 import org.apache.logging.log4j.core.LoggerContext; 024 025 /** 026 * Convenience methods for retrieving the {@link org.apache.logging.log4j.core.LoggerContext} associated with a 027 * particular ServletContext. These methods are most particularly useful for asynchronous servlets where the 028 * <abbr title="Thread Context ClassLoader">TCCL</abbr> is potentially different from the TCCL used by the 029 * Servlet container that bootstrapped Log4j. 030 * 031 * @since 2.0.1 032 */ 033 public final class WebLoggerContextUtils { 034 private WebLoggerContextUtils() { 035 } 036 037 private static final Lock WEB_SUPPORT_LOOKUP = new ReentrantLock(); 038 039 /** 040 * Finds the main {@link org.apache.logging.log4j.core.LoggerContext} configured for the given ServletContext. 041 * 042 * @param servletContext the ServletContext to locate a LoggerContext for 043 * @return the LoggerContext for the given ServletContext 044 * @throws java.lang.IllegalStateException if no LoggerContext could be found on the given ServletContext 045 * @since 2.0.1 046 */ 047 public static LoggerContext getWebLoggerContext(final ServletContext servletContext) { 048 return (LoggerContext) servletContext.getAttribute(Log4jWebSupport.CONTEXT_ATTRIBUTE); 049 } 050 051 /** 052 * Finds the main {@link org.apache.logging.log4j.core.LoggerContext} configured for the given ServletContext. 053 * 054 * @param servletContext the ServletContext to locate a LoggerContext for 055 * @return the LoggerContext for the given ServletContext or {@code null} if none was set 056 * @since 2.0.1 057 */ 058 public static LoggerContext getRequiredWebLoggerContext(final ServletContext servletContext) { 059 final LoggerContext loggerContext = getWebLoggerContext(servletContext); 060 if (loggerContext == null) { 061 throw new IllegalStateException( 062 "No LoggerContext found in ServletContext attribute " + Log4jWebSupport.CONTEXT_ATTRIBUTE); 063 } 064 return loggerContext; 065 } 066 067 /** 068 * Finds or initializes the {@link org.apache.logging.log4j.web.Log4jWebLifeCycle} singleton for the given 069 * ServletContext. 070 * 071 * @param servletContext the ServletContext to get the Log4jWebLifeCycle for 072 * @return the Log4jWebLifeCycle for the given ServletContext 073 * @since 2.0.1 074 */ 075 public static Log4jWebLifeCycle getWebLifeCycle(final ServletContext servletContext) { 076 WEB_SUPPORT_LOOKUP.lock(); 077 try { 078 Log4jWebLifeCycle webLifeCycle = (Log4jWebLifeCycle) servletContext.getAttribute( 079 Log4jWebSupport.SUPPORT_ATTRIBUTE); 080 if (webLifeCycle == null) { 081 webLifeCycle = Log4jWebInitializerImpl.initialize(servletContext); 082 } 083 return webLifeCycle; 084 } finally { 085 WEB_SUPPORT_LOOKUP.unlock(); 086 } 087 } 088 089 /** 090 * Wraps a Runnable instance by setting its thread context {@link org.apache.logging.log4j.core.LoggerContext} 091 * before execution and clearing it after execution. 092 * 093 * @param servletContext the ServletContext to locate a LoggerContext for 094 * @param runnable the Runnable to wrap execution for 095 * @return a wrapped Runnable 096 * @since 2.0.1 097 */ 098 public static Runnable wrapExecutionContext(final ServletContext servletContext, final Runnable runnable) { 099 return new Runnable() { 100 @Override 101 public void run() { 102 final Log4jWebSupport webSupport = getWebLifeCycle(servletContext); 103 webSupport.setLoggerContext(); 104 try { 105 runnable.run(); 106 } finally { 107 webSupport.clearLoggerContext(); 108 } 109 } 110 }; 111 } 112 }