Source Code for Apache Log4j Tag Library

Apache Log4j Tag Library creates the capability of inserting log statements in JSPs without the use of Java scripting.

Bytecode (Java 8) for Apache Log4j Tag Library is provided in a separate JAR file like log4j-taglib-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 Tag Library 2.14.1 below.

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org/apache/logging/log4j/taglib/TagUtils.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.taglib;

import java.util.HashSet;
import java.util.Set;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LoggingException;
import org.apache.logging.log4j.Marker;
import org.apache.logging.log4j.message.MessageFactory;
import org.apache.logging.log4j.spi.AbstractLogger;
import org.apache.logging.log4j.status.StatusLogger;

/**
 * Provides support for logging tags.
 *
 * @since 2.0
 */
final class TagUtils {
    private static final StatusLogger LOGGER = StatusLogger.getLogger();

    private static final Set<Object> WARNED_FOR = new HashSet<>();

    private static final String LOGGER_SCOPE_ATTRIBUTE = "org.apache.logging.log4j.taglib.LOGGER_SCOPE_ATTRIBUTE";

    private TagUtils() {
        throw new RuntimeException("TagUtils cannot be instantiated.");
    }

    static int getScope(final String scope) {
        if ("request".equalsIgnoreCase(scope)) {
            return PageContext.REQUEST_SCOPE;
        }
        if ("session".equalsIgnoreCase(scope)) {
            return PageContext.SESSION_SCOPE;
        }
        if ("application".equalsIgnoreCase(scope)) {
            return PageContext.APPLICATION_SCOPE;
        }
        return PageContext.PAGE_SCOPE;
    }

    static Level resolveLevel(final Object level) {
        if (level instanceof Level) {
            return (Level) level;
        }
        if (level instanceof String) {
            return Level.toLevel((String) level);
        }
        return null;
    }

    static Log4jTaglibLogger resolveLogger(final Log4jTaglibLoggerContext context, final Object logger,
                                           final MessageFactory factory) throws JspException {
        if (logger instanceof Logger) {
            if (logger instanceof Log4jTaglibLogger) {
                return (Log4jTaglibLogger) logger;
            }
            if (logger instanceof AbstractLogger) {
                if (LOGGER.isInfoEnabled() && !WARNED_FOR.contains(logger)) {
                    LOGGER.info("Constructing new Log4jTaglibLogger from AbstractLogger {} name and message factory.",
                            logger.getClass().getName());
                    WARNED_FOR.add(logger);
                }
                final AbstractLogger original = (AbstractLogger) logger;
                return getLogger(context, original.getName(), original.getMessageFactory());
            }
            throw new JspException(
                    "Log4j Tag Library requires base logging system to extend Log4j AbstractLogger.");
        }
        if (logger instanceof String) {
            return getLogger(context, (String) logger, factory);
        }
        throw new JspException("Logger must be of type String or org.apache.logging.log4j.Logger.");
    }

    private static Log4jTaglibLogger getLogger(final Log4jTaglibLoggerContext context, final String name,
                                               final MessageFactory factory)
            throws JspException {
        try {
            return context.getLogger(name, factory);
        } catch (final LoggingException e) {
            throw new JspException(e.getMessage(), e);
        }
    }

    static void setDefaultLogger(final PageContext pageContext, final Log4jTaglibLogger logger) {
        pageContext.setAttribute(TagUtils.LOGGER_SCOPE_ATTRIBUTE, logger, PageContext.PAGE_SCOPE);
    }

    static Log4jTaglibLogger getDefaultLogger(final PageContext pageContext) {
        return (Log4jTaglibLogger) pageContext.getAttribute(TagUtils.LOGGER_SCOPE_ATTRIBUTE, PageContext.PAGE_SCOPE);
    }

    static boolean isEnabled(final Log4jTaglibLogger logger, final Level level, final Marker marker) {
        if (marker == null) {
            return logger.isEnabled(level);
        }
        return logger.isEnabled(level, marker, (Object) null, null);
    }
}

org/apache/logging/log4j/taglib/TagUtils.java

 

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