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/config/plugins/visitors/PluginVisitor.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.config.plugins.visitors;

import java.lang.annotation.Annotation;
import java.lang.reflect.Member;

import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.Node;
import org.apache.logging.log4j.core.lookup.StrSubstitutor;

/**
 * Visitor strategy for parsing data from a {@link Node}, doing any relevant type conversion, and returning a
 * parsed value for that variable. Implementations must be constructable using the default constructor.
 *
 * @param <A> the Annotation type.
 */
public interface PluginVisitor<A extends Annotation> {

    /**
     * Sets the Annotation to be used for this. If the given Annotation is not compatible with this class's type, then
     * it is ignored.
     *
     * @param annotation the Annotation instance.
     * @return {@code this}.
     * @throws NullPointerException if the argument is {@code null}.
     */
    PluginVisitor<A> setAnnotation(Annotation annotation);

    /**
     * Sets the list of aliases to use for this visit. No aliases are required, however.
     *
     * @param aliases the list of aliases to use.
     * @return {@code this}.
     */
    PluginVisitor<A> setAliases(String... aliases);

    /**
     * Sets the class to convert the plugin value to on this visit. This should correspond with a class obtained from
     * a factory method or builder class field. Not all PluginVisitor implementations may need this value.
     *
     * @param conversionType the type to convert the plugin string to (if applicable).
     * @return {@code this}.
     * @throws NullPointerException if the argument is {@code null}.
     */
    PluginVisitor<A> setConversionType(Class<?> conversionType);

    /**
     * Sets the StrSubstitutor to use for converting raw strings before type conversion. Generally obtained from a
     * {@link org.apache.logging.log4j.core.config.Configuration}.
     *
     * @param substitutor the StrSubstitutor to use on plugin values.
     * @return {@code this}.
     * @throws NullPointerException if the argument is {@code null}.
     */
    PluginVisitor<A> setStrSubstitutor(StrSubstitutor substitutor);

    /**
     * Sets the Member that this visitor is being used for injection upon. For instance, this could be the Field
     * that is being used for injecting a value, or it could be the factory method being used to inject parameters
     * into.
     *
     * @param member the member this visitor is parsing a value for.
     * @return {@code this}.
     */
    PluginVisitor<A> setMember(Member member);

    /**
     * Visits a Node to obtain a value for constructing a Plugin object.
     *
     * @param configuration the current Configuration.
     * @param node          the current Node corresponding to the Plugin object being created.
     * @param event         the current LogEvent that caused this Plugin object to be made (optional).
     * @param log           the StringBuilder being used to build a debug message.
     * @return the converted value to be used for Plugin creation.
     */
    Object visit(Configuration configuration, Node node, LogEvent event, StringBuilder log);
}

⏎ org/apache/logging/log4j/core/config/plugins/visitors/PluginVisitor.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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