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/Log4jServletFilter.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.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.status.StatusLogger;

/**
 * This is responsible for the following:
 * <ul>
 *     <li>Clearing the logger context when the application has finished starting up.</li>
 *     <li>Setting the logger context before processing a request and clearing it after processing a request.</li>
 *     <li>Setting the logger context when the application is starting to shut down.</li>
 * </ul>
 * This filter is a once-per-request filter. It is capable of filtering all the different types of requests
 * (standard, asynchronous, error, etc.) but will not apply processing if the filter matches multiple times on the same
 * logical request.
 */
public class Log4jServletFilter implements Filter {

    private static final Logger LOGGER = StatusLogger.getLogger();

    static final String ALREADY_FILTERED_ATTRIBUTE = Log4jServletFilter.class.getName() + ".FILTERED";

    private ServletContext servletContext;
    private Log4jWebLifeCycle initializer;

    @Override
    public void init(final FilterConfig filterConfig) throws ServletException {
        this.servletContext = filterConfig.getServletContext();
        LOGGER.debug("Log4jServletFilter initialized.");

        this.initializer = WebLoggerContextUtils.getWebLifeCycle(this.servletContext);
        this.initializer.clearLoggerContext(); // the application is mostly finished starting up now
    }

    @Override
    public void doFilter(final ServletRequest request, final ServletResponse response, final FilterChain chain)
            throws IOException, ServletException {
        if (request.getAttribute(ALREADY_FILTERED_ATTRIBUTE) != null) {
            chain.doFilter(request, response);
        } else {
            request.setAttribute(ALREADY_FILTERED_ATTRIBUTE, Boolean.TRUE);

            try {
                this.initializer.setLoggerContext();

                chain.doFilter(request, response);
            } finally {
                this.initializer.clearLoggerContext();
            }
        }
    }

    @Override
    public void destroy() {
        if (this.servletContext == null || this.initializer == null) {
            throw new IllegalStateException("Filter destroyed before it was initialized.");
        }
        LOGGER.debug("Log4jServletFilter destroyed.");

        this.initializer.setLoggerContext(); // the application is just now starting to shut down
    }
}

org/apache/logging/log4j/web/Log4jServletFilter.java

 

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2015-11-04, 6880👍, 0💬