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/MapPatternConverter.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 org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.message.MapMessage;
import org.apache.logging.log4j.message.MapMessage.MapFormat;

import java.util.Objects;

/**
 * Able to handle the contents of the LogEvent's MapMessage and either
 * output the entire contents of the properties in a similar format to the
 * java.util.Hashtable.toString(), or to output the value of a specific key
 * within the Map.
 */
@Plugin(name = "MapPatternConverter", category = PatternConverter.CATEGORY)
@ConverterKeys({ "K", "map", "MAP" })
public final class MapPatternConverter extends LogEventPatternConverter {

    private static final String JAVA_UNQUOTED = MapFormat.JAVA_UNQUOTED.name();

    /**
     * Name of property to output.
     */
    private final String key;

    /**
     * Format to use when no key is provided.
     *
     * @see MapFormat
     * @since 2.11.2
     */
    private final String[] format;

    /**
     * Private constructor.
     *
     * @param options options, may be null.
     */
    private MapPatternConverter(final String[] options, String... format) {
        super(options != null && options.length > 0 ? "MAP{" + options[0] + '}' : "MAP", "map");
        key = options != null && options.length > 0 ? options[0] : null;
        this.format = format;
    }

    /**
     * Obtains an instance of {@link MapPatternConverter}.
     *
     * @param options options, may be null or first element contains name of property to format.
     * @return instance of {@link MapPatternConverter}.
     */
    public static MapPatternConverter newInstance(final String[] options) {
        return new MapPatternConverter(options, JAVA_UNQUOTED);
    }

    /**
     * Obtain an instance of {@link MapPatternConverter}.
     *
     * @param options options, may be null or first element contains name of property to format.
     * @param format the format to use if no options are given (i.e., options is null). Ignored if options is non-null.
     * @return instance of {@link MapPatternConverter}.
     * @since 2.11.2
     */
    public static MapPatternConverter newInstance(final String[] options, final MapFormat format) {
        return new MapPatternConverter(options, Objects.toString(format, JAVA_UNQUOTED));
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void format(final LogEvent event, final StringBuilder toAppendTo) {
        MapMessage msg;
        if (event.getMessage() instanceof MapMessage) {
            msg = (MapMessage) event.getMessage();
        } else {
            return;
        }
        // if there is no additional options, we output every single
        // Key/Value pair for the Map in a similar format to Hashtable.toString()
        if (key == null) {
            msg.formatTo(format, toAppendTo);
        } else {
            // otherwise they just want a single key output
            final String val = msg.get(key);

            if (val != null) {
                toAppendTo.append(val);
            }
        }
    }
}

⏎ org/apache/logging/log4j/core/pattern/MapPatternConverter.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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