Source Code for Apache Log4j Web Servlet Containers

Apache Log4j Web Servlet Containers provides support for automatically enabling Log4j in Servlet containers.

Bytecode (Java 8) for Apache Log4j Web Servlet Containers is provided in a separate JAR file like log4j-web-2.14.1.jar.

Source Code files for Apache Log4j IOStreams are provided in both binary packge like apache-log4j-2.14.1-bin.zip and source package like apache-log4j-2.14.1-src.zip. You can download them at Apache Log4j Website.

You can also browse Source Code files for Apache Log4j Web Servlet Containers 2.14.1 below.

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org/apache/logging/log4j/web/WebLoggerContextUtils.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.logging.log4j.web;

import java.util.AbstractMap;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import javax.servlet.ServletContext;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.impl.ContextAnchor;

/**
 * Convenience methods for retrieving the {@link org.apache.logging.log4j.core.LoggerContext} associated with a
 * particular ServletContext. These methods are most particularly useful for asynchronous servlets where the
 * Thread Context ClassLoader (TCCL) is potentially different from the TCCL used by the
 * Servlet container that bootstrapped Log4j.
 *
 * @since 2.0.1
 */
public final class WebLoggerContextUtils {
    private WebLoggerContextUtils() {
    }

    private static final Lock WEB_SUPPORT_LOOKUP = new ReentrantLock();
    private static final String SERVLET_CONTEXT = "__SERVLET_CONTEXT__";

    /**
     * Finds the main {@link org.apache.logging.log4j.core.LoggerContext} configured for the given ServletContext.
     *
     * @param servletContext the ServletContext to locate a LoggerContext for
     * @return the LoggerContext for the given ServletContext
     * @since 2.0.1
     */
    public static LoggerContext getWebLoggerContext(final ServletContext servletContext) {
        return (LoggerContext) servletContext.getAttribute(Log4jWebSupport.CONTEXT_ATTRIBUTE);
    }

    /**
     * Finds the main {@link org.apache.logging.log4j.core.LoggerContext} configured for the given ServletContext.
     *
     * @param servletContext the ServletContext to locate a LoggerContext for
     * @return the LoggerContext for the given ServletContext or {@code null} if none was set
     * @throws java.lang.IllegalStateException if no LoggerContext could be found on the given ServletContext
     * @since 2.0.1
     */
    public static LoggerContext getRequiredWebLoggerContext(final ServletContext servletContext) {
        final LoggerContext loggerContext = getWebLoggerContext(servletContext);
        if (loggerContext == null) {
            throw new IllegalStateException(
                "No LoggerContext found in ServletContext attribute " + Log4jWebSupport.CONTEXT_ATTRIBUTE);
        }
        return loggerContext;
    }

    /**
     * Finds or initializes the {@link org.apache.logging.log4j.web.Log4jWebLifeCycle} singleton for the given
     * ServletContext.
     *
     * @param servletContext the ServletContext to get the Log4jWebLifeCycle for
     * @return the Log4jWebLifeCycle for the given ServletContext
     * @since 2.0.1
     */
    public static Log4jWebLifeCycle getWebLifeCycle(final ServletContext servletContext) {
        WEB_SUPPORT_LOOKUP.lock();
        try {
            Log4jWebLifeCycle webLifeCycle = (Log4jWebLifeCycle) servletContext.getAttribute(
                Log4jWebSupport.SUPPORT_ATTRIBUTE);
            if (webLifeCycle == null) {
                webLifeCycle = Log4jWebInitializerImpl.initialize(servletContext);
            }
            return webLifeCycle;
        } finally {
            WEB_SUPPORT_LOOKUP.unlock();
        }
    }

    /**
     * Wraps a Runnable instance by setting its thread context {@link org.apache.logging.log4j.core.LoggerContext}
     * before execution and clearing it after execution.
     *
     * @param servletContext the ServletContext to locate a LoggerContext for
     * @param runnable       the Runnable to wrap execution for
     * @return a wrapped Runnable
     * @since 2.0.1
     */
    public static Runnable wrapExecutionContext(final ServletContext servletContext, final Runnable runnable) {
        return () -> {
            final Log4jWebSupport webSupport = getWebLifeCycle(servletContext);
            webSupport.setLoggerContext();
            try {
                runnable.run();
            } finally {
                webSupport.clearLoggerContext();
            }
        };
    }

    public static Map.Entry<String, Object> createExternalEntry(ServletContext servletContext) {
        return new AbstractMap.SimpleEntry<>(SERVLET_CONTEXT, servletContext);
    }

    public static void setServletContext(LoggerContext lc, ServletContext servletContext) {
        if (lc != null) {
            lc.putObject(SERVLET_CONTEXT, servletContext);
        }
    }

    /**
     * Gets the current {@link ServletContext} if it has already been assigned to a LoggerContext's external context.
     *
     * @return the current ServletContext attached to a LoggerContext or {@code null} if none could be found
     * @since 2.1
     */
    public static ServletContext getServletContext() {
        org.apache.logging.log4j.spi.LoggerContext lc = ContextAnchor.THREAD_CONTEXT.get();
        if (lc == null) {
            lc = LogManager.getContext(false);
        }

        Object obj = lc != null ? lc.getObject(SERVLET_CONTEXT) : null;
        if (obj instanceof ServletContext) {
            return (ServletContext) obj;
        }
        return null;
    }
}

org/apache/logging/log4j/web/WebLoggerContextUtils.java

 

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