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/convert/TypeConverterRegistry.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.convert;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Collection;
import java.util.Map;
import java.util.Objects;
import java.util.UnknownFormatConversionException;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
import org.apache.logging.log4j.core.config.plugins.util.PluginType;
import org.apache.logging.log4j.core.util.ReflectionUtil;
import org.apache.logging.log4j.core.util.TypeUtil;
import org.apache.logging.log4j.status.StatusLogger;

/**
 * Registry for {@link TypeConverter} plugins.
 *
 * @since 2.1
 */
public class TypeConverterRegistry {

    private static final Logger LOGGER = StatusLogger.getLogger();
    private static volatile TypeConverterRegistry INSTANCE;
    private static final Object INSTANCE_LOCK = new Object();

    private final ConcurrentMap<Type, TypeConverter<?>> registry = new ConcurrentHashMap<>();

    /**
     * Gets the singleton instance of the TypeConverterRegistry.
     *
     * @return the singleton instance.
     */
    public static TypeConverterRegistry getInstance() {
        TypeConverterRegistry result = INSTANCE;
        if (result == null) {
            synchronized (INSTANCE_LOCK) {
                result = INSTANCE;
                if (result == null) {
                    INSTANCE = result = new TypeConverterRegistry();
                }
            }
        }
        return result;
    }

    /**
     * Finds a {@link TypeConverter} for the given {@link Type}, falling back to an assignment-compatible TypeConverter
     * if none exist for the given type. That is, if the given Type does not have a TypeConverter, but another Type
     * which can be assigned to the given Type <em>does</em> have a TypeConverter, then that TypeConverter will be
     * used and registered.
     *
     * @param type the Type to find a TypeConverter for (must not be {@code null}).
     * @return a TypeConverter for the given Type.
     * @throws UnknownFormatConversionException if no TypeConverter can be found for the given type.
     */
    public TypeConverter<?> findCompatibleConverter(final Type type) {
        Objects.requireNonNull(type, "No type was provided");
        final TypeConverter<?> primary = registry.get(type);
        // cached type converters
        if (primary != null) {
            return primary;
        }
        // dynamic enum support
        if (type instanceof Class<?>) {
            final Class<?> clazz = (Class<?>) type;
            if (clazz.isEnum()) {
                @SuppressWarnings({"unchecked","rawtypes"})
                final EnumConverter<? extends Enum> converter = new EnumConverter(clazz.asSubclass(Enum.class));
                registry.putIfAbsent(type, converter);
                return converter;
            }
        }
        // look for compatible converters
        for (final Map.Entry<Type, TypeConverter<?>> entry : registry.entrySet()) {
            final Type key = entry.getKey();
            if (TypeUtil.isAssignable(type, key)) {
                LOGGER.debug("Found compatible TypeConverter<{}> for type [{}].", key, type);
                final TypeConverter<?> value = entry.getValue();
                registry.putIfAbsent(type, value);
                return value;
            }
        }
        throw new UnknownFormatConversionException(type.toString());
    }

    private TypeConverterRegistry() {
        LOGGER.trace("TypeConverterRegistry initializing.");
        final PluginManager manager = new PluginManager(TypeConverters.CATEGORY);
        manager.collectPlugins();
        loadKnownTypeConverters(manager.getPlugins().values());
        registerPrimitiveTypes();
    }

    private void loadKnownTypeConverters(final Collection<PluginType<?>> knownTypes) {
        for (final PluginType<?> knownType : knownTypes) {
            final Class<?> clazz = knownType.getPluginClass();
            if (TypeConverter.class.isAssignableFrom(clazz)) {
                @SuppressWarnings("rawtypes")
                final Class<? extends TypeConverter> pluginClass =  clazz.asSubclass(TypeConverter.class);
                final Type conversionType = getTypeConverterSupportedType(pluginClass);
                final TypeConverter<?> converter = ReflectionUtil.instantiate(pluginClass);
                if (registry.putIfAbsent(conversionType, converter) != null) {
                    LOGGER.warn("Found a TypeConverter [{}] for type [{}] that already exists.", converter,
                        conversionType);
                }
            }
        }
    }

    private static Type getTypeConverterSupportedType(@SuppressWarnings("rawtypes") final Class<? extends TypeConverter> typeConverterClass) {
        for (final Type type : typeConverterClass.getGenericInterfaces()) {
            if (type instanceof ParameterizedType) {
                final ParameterizedType pType = (ParameterizedType) type;
                if (TypeConverter.class.equals(pType.getRawType())) {
                    // TypeConverter<T> has only one type argument (T), so return that
                    return pType.getActualTypeArguments()[0];
                }
            }
        }
        return Void.TYPE;
    }

    private void registerPrimitiveTypes() {
        registerTypeAlias(Boolean.class, Boolean.TYPE);
        registerTypeAlias(Byte.class, Byte.TYPE);
        registerTypeAlias(Character.class, Character.TYPE);
        registerTypeAlias(Double.class, Double.TYPE);
        registerTypeAlias(Float.class, Float.TYPE);
        registerTypeAlias(Integer.class, Integer.TYPE);
        registerTypeAlias(Long.class, Long.TYPE);
        registerTypeAlias(Short.class, Short.TYPE);
    }

    private void registerTypeAlias(final Type knownType, final Type aliasType) {
        registry.putIfAbsent(aliasType, registry.get(knownType));
    }

}

⏎ org/apache/logging/log4j/core/config/plugins/convert/TypeConverterRegistry.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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