Apache Log4j Core Implementation provides the functional components of the logging system. Users are free to create their own plugins and include them in the logging configuration. Apache Log4j Core is a required module to use Apache Log4j.

Bytecode (Java 8) for Apache Log4j Core Implementation is provided in a separate JAR file like log4j-core-2.14.1.jar.

Source Code files for Apache Log4j API 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 Core Implementation 2.14.1 below.

⏎ org/apache/logging/log4j/core/pattern/LevelPatternConverter.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.core.pattern;

import java.util.HashMap;
import java.util.Locale;
import java.util.Map;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.util.Patterns;
import org.apache.logging.log4j.util.PerformanceSensitive;

/**
 * Returns the event's level in a StringBuilder.
 */
@Plugin(name = "LevelPatternConverter", category = PatternConverter.CATEGORY)
@ConverterKeys({ "p", "level" })
@PerformanceSensitive("allocation")
public final class LevelPatternConverter extends LogEventPatternConverter {
    private static final String OPTION_LENGTH = "length";
    private static final String OPTION_LOWER = "lowerCase";

    /**
     * Singleton.
     */
    private static final LevelPatternConverter INSTANCE = new LevelPatternConverter(null);

    private final Map<Level, String> levelMap;

    /**
     * Private constructor.
     */
    private LevelPatternConverter(final Map<Level, String> map) {
        super("Level", "level");
        this.levelMap = map;
    }

    /**
     * Obtains an instance of pattern converter.
     *
     * @param options
     *            options, may be null. May contain a list of level names and The value that should be displayed for the
     *            Level.
     * @return instance of pattern converter.
     */
    public static LevelPatternConverter newInstance(final String[] options) {
        if (options == null || options.length == 0) {
            return INSTANCE;
        }
        final Map<Level, String> levelMap = new HashMap<>();
        int length = Integer.MAX_VALUE; // More than the longest level name.
        boolean lowerCase = false;
        final String[] definitions = options[0].split(Patterns.COMMA_SEPARATOR);
        for (final String def : definitions) {
            final String[] pair = def.split("=");
            if (pair == null || pair.length != 2) {
                LOGGER.error("Invalid option {}", def);
                continue;
            }
            final String key = pair[0].trim();
            final String value = pair[1].trim();
            if (OPTION_LENGTH.equalsIgnoreCase(key)) {
                length = Integer.parseInt(value);
            } else if (OPTION_LOWER.equalsIgnoreCase(key)) {
                lowerCase = Boolean.parseBoolean(value);
            } else {
                final Level level = Level.toLevel(key, null);
                if (level == null) {
                    LOGGER.error("Invalid Level {}", key);
                } else {
                    levelMap.put(level, value);
                }
            }
        }
        if (levelMap.isEmpty() && length == Integer.MAX_VALUE && !lowerCase) {
            return INSTANCE;
        }
        for (final Level level : Level.values()) {
            if (!levelMap.containsKey(level)) {
                final String left = left(level, length);
                levelMap.put(level, lowerCase ? left.toLowerCase(Locale.US) : left);
            }
        }
        return new LevelPatternConverter(levelMap);
    }

    /**
     * Returns the leftmost chars of the level name for the given level.
     *
     * @param level
     *            The level
     * @param length
     *            How many chars to return
     * @return The abbreviated level name, or the whole level name if the {@code length} is greater than the level name
     *         length,
     */
    private static String left(final Level level, final int length) {
        final String string = level.toString();
        if (length >= string.length()) {
            return string;
        }
        return string.substring(0, length);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void format(final LogEvent event, final StringBuilder output) {
        output.append(levelMap == null ? event.getLevel().toString() : levelMap.get(event.getLevel()));
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String getStyleClass(final Object e) {
        if (e instanceof LogEvent) {
            return "level " + ((LogEvent) e).getLevel().name().toLowerCase(Locale.ENGLISH);
        }

        return "level";
    }
}

⏎ org/apache/logging/log4j/core/pattern/LevelPatternConverter.java

Or download all of them as a single archive file:

File name: log4j-core-2.14.1-sources.jar
File size: 1281358 bytes
Release date: 2021-03-06
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