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/appender/db/jdbc/ColumnConfig.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.appender.db.jdbc;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.Core;
import org.apache.logging.log4j.core.appender.db.ColumnMapping;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginBuilderAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginBuilderFactory;
import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
import org.apache.logging.log4j.core.config.plugins.validation.constraints.Required;
import org.apache.logging.log4j.core.layout.PatternLayout;
import org.apache.logging.log4j.core.util.Booleans;
import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.Strings;

/**
 * A configuration element used to configure which event properties are logged to which columns in the database table.
 *
 * @see ColumnMapping
 */
@Plugin(name = "Column", category = Core.CATEGORY_NAME, printObject = true)
public final class ColumnConfig {
    public static class Builder implements org.apache.logging.log4j.core.util.Builder<ColumnConfig> {

        @PluginConfiguration
        private Configuration configuration;

        @PluginBuilderAttribute
        @Required(message = "No name provided")
        private String name;

        @PluginBuilderAttribute
        private String pattern;

        @PluginBuilderAttribute
        private String literal;

        @PluginBuilderAttribute
        private boolean isEventTimestamp;

        @PluginBuilderAttribute
        private boolean isUnicode = true;

        @PluginBuilderAttribute
        private boolean isClob;

        @Override
        public ColumnConfig build() {
            if (Strings.isEmpty(name)) {
                LOGGER.error("The column config is not valid because it does not contain a column name.");
                return null;
            }

            final boolean isPattern = Strings.isNotEmpty(pattern);
            final boolean isLiteralValue = Strings.isNotEmpty(literal);

            if ((isPattern && isLiteralValue) || (isPattern && isEventTimestamp) || (isLiteralValue && isEventTimestamp)) {
                LOGGER.error("The pattern, literal, and isEventTimestamp attributes are mutually exclusive.");
                return null;
            }

            if (isEventTimestamp) {
                return new ColumnConfig(name, null, null, true, false, false);
            }

            if (isLiteralValue) {
                return new ColumnConfig(name, null, literal, false, false, false);
            }

            if (isPattern) {
                final PatternLayout layout =
                    PatternLayout.newBuilder()
                        .withPattern(pattern)
                        .withConfiguration(configuration)
                        .withAlwaysWriteExceptions(false)
                        .build();
                return new ColumnConfig(name, layout, null, false, isUnicode, isClob);
            }

            LOGGER.error("To configure a column you must specify a pattern or literal or set isEventDate to true.");
            return null;
        }

        /**
         * If {@code "true"}, indicates that the column is a character LOB (CLOB).
         *
         * @return this.
         */
        public Builder setClob(final boolean clob) {
            isClob = clob;
            return this;
        }

        /**
         * The configuration object.
         *
         * @return this.
         */
        public Builder setConfiguration(final Configuration configuration) {
            this.configuration = configuration;
            return this;
        }

        /**
         * If {@code "true"}, indicates that this column is a date-time column in which the event timestamp should be
         * inserted. Mutually exclusive with {@code pattern!=null} and {@code literal!=null}.
         *
         * @return this.
         */
        public Builder setEventTimestamp(final boolean eventTimestamp) {
            isEventTimestamp = eventTimestamp;
            return this;
        }

        /**
         * The literal value to insert into the column as-is without any quoting or escaping. Mutually exclusive with
         * {@code pattern!=null} and {@code eventTimestamp=true}.
         *
         * @return this.
         */
        public Builder setLiteral(final String literal) {
            this.literal = literal;
            return this;
        }

        /**
         * The name of the database column as it exists within the database table.
         *
         * @return this.
         */
        public Builder setName(final String name) {
            this.name = name;
            return this;
        }

        /**
         * The {@link PatternLayout} pattern to insert in this column. Mutually exclusive with
         * {@code literal!=null} and {@code eventTimestamp=true}
         *
         * @return this.
         */
        public Builder setPattern(final String pattern) {
            this.pattern = pattern;
            return this;
        }

        /**
         * If {@code "true"}, indicates that the column is a Unicode String.
         *
         * @return this.
         */
        public Builder setUnicode(final boolean unicode) {
            isUnicode = unicode;
            return this;
        }
    }

    private static final Logger LOGGER = StatusLogger.getLogger();
    /**
     * Factory method for creating a column config within the plugin manager.
     *
     * @see Builder
     * @deprecated use {@link #newBuilder()}
     */
    @Deprecated
    public static ColumnConfig createColumnConfig(final Configuration config, final String name, final String pattern,
                                                  final String literalValue, final String eventTimestamp,
                                                  final String unicode, final String clob) {
        if (Strings.isEmpty(name)) {
            LOGGER.error("The column config is not valid because it does not contain a column name.");
            return null;
        }

        final boolean isEventTimestamp = Boolean.parseBoolean(eventTimestamp);
        final boolean isUnicode = Booleans.parseBoolean(unicode, true);
        final boolean isClob = Boolean.parseBoolean(clob);

        return newBuilder()
            .setConfiguration(config)
            .setName(name)
            .setPattern(pattern)
            .setLiteral(literalValue)
            .setEventTimestamp(isEventTimestamp)
            .setUnicode(isUnicode)
            .setClob(isClob)
            .build();
    }
    @PluginBuilderFactory
    public static Builder newBuilder() {
        return new Builder();
    }
    private final String columnName;
    private final String columnNameKey;
    private final PatternLayout layout;
    private final String literalValue;

    private final boolean eventTimestamp;

    private final boolean unicode;

    private final boolean clob;

    private ColumnConfig(final String columnName, final PatternLayout layout, final String literalValue,
                         final boolean eventDate, final boolean unicode, final boolean clob) {
        this.columnName = columnName;
        this.columnNameKey = ColumnMapping.toKey(columnName);
        this.layout = layout;
        this.literalValue = literalValue;
        this.eventTimestamp = eventDate;
        this.unicode = unicode;
        this.clob = clob;
    }

    public String getColumnName() {
        return this.columnName;
    }

    public String getColumnNameKey() {
        return this.columnNameKey;
    }

    public PatternLayout getLayout() {
        return this.layout;
    }

    public String getLiteralValue() {
        return this.literalValue;
    }

    public boolean isClob() {
        return this.clob;
    }

    public boolean isEventTimestamp() {
        return this.eventTimestamp;
    }

    public boolean isUnicode() {
        return this.unicode;
    }

    @Override
    public String toString() {
        return "{ name=" + this.columnName + ", layout=" + this.layout + ", literal=" + this.literalValue
                + ", timestamp=" + this.eventTimestamp + " }";
    }
}

⏎ org/apache/logging/log4j/core/appender/db/jdbc/ColumnConfig.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
Download 

⇒ Source Code for Apache Log4j JDK Logging Adapter

⇐ Source Code for Apache Log4j API

⇑ Downloading and Reviewing Apache Log4j Packages

⇑⇑ FAQ for Apache Log4j