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.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;

import java.io.Serializable;

/**
 * Appends {@link LogEvent}s. An Appender can contain a {@link Layout} if applicable as well
 * as an {@link ErrorHandler}. Typical Appender implementations coordinate with an
 * implementation of {@link org.apache.logging.log4j.core.appender.AbstractManager} to handle external resources
 * such as streams, connections, and other shared state. As Appenders are plugins, concrete implementations need to
 * be annotated with {@link org.apache.logging.log4j.core.config.plugins.Plugin} and need to provide a static
 * factory method annotated with {@link org.apache.logging.log4j.core.config.plugins.PluginFactory}.
 *
 * <p>Most core plugins are written using a related Manager class that handle the actual task of serializing a
 * {@link LogEvent} to some output location. For instance, many Appenders can take
 * advantage of the {@link org.apache.logging.log4j.core.appender.OutputStreamManager} class.</p>
 *
 * <p>It is recommended that Appenders don't do any heavy lifting since there can be many instances of the class
 * being used at any given time. When resources require locking (e.g., through {@link java.nio.channels.FileLock}),
 * it is important to isolate synchronized code to prevent concurrency issues.</p>
 */
public interface Appender extends LifeCycle {

    /**
     * Main {@linkplain org.apache.logging.log4j.core.config.plugins.Plugin#elementType() plugin element type} for
     * Appender plugins.
     *
     * @since 2.6
     */
    String ELEMENT_TYPE = "appender";

    /**
     * Logs a LogEvent using whatever logic this Appender wishes to use. It is typically recommended to use a
     * bridge pattern not only for the benefits from decoupling an Appender from its implementation, but it is also
     * handy for sharing resources which may require some form of locking.
     *
     * @param event The LogEvent.
     */
    void append(LogEvent event);


    /**
     * Gets the name of this Appender.
     *
     * @return name, may be null.
     */
    String getName();

    /**
     * Returns the Layout used by this Appender if applicable.
     *
     * @return the Layout for this Appender or {@code null} if none is configured.
     */
    Layout<? extends Serializable> getLayout();

    /**
     * Some Appenders need to propagate exceptions back to the application. When {@code ignoreExceptions} is
     * {@code false} the AppenderControl will allow the exception to percolate.
     *
     * @return {@code true} if exceptions will be logged but not thrown, {@code false} otherwise.
     */
    boolean ignoreExceptions();

    /**
     * Gets the {@link ErrorHandler} used for handling exceptions.
     *
     * @return the ErrorHandler for handling exceptions.
     */
    ErrorHandler getHandler();

    /**
     * Sets the {@link ErrorHandler} used for handling exceptions.
     *
     * @param handler the ErrorHandler to use for handling exceptions.
     */
    void setHandler(ErrorHandler handler);
}

⏎ org/apache/logging/log4j/core/Appender.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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