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/impl/JdkMapAdapterStringMap.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.impl;

import java.util.Arrays;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

import org.apache.logging.log4j.util.BiConsumer;
import org.apache.logging.log4j.util.ReadOnlyStringMap;
import org.apache.logging.log4j.util.StringMap;
import org.apache.logging.log4j.util.TriConsumer;

/**
 * Provides a read-only {@code StringMap} view of a {@code Map<String, String>}.
 */
public class JdkMapAdapterStringMap implements StringMap {
    private static final long serialVersionUID = -7348247784983193612L;
    private static final String FROZEN = "Frozen collection cannot be modified";
    private static final Comparator<? super String> NULL_FIRST_COMPARATOR = (left, right) -> {
        if (left == null) {
            return -1;
        }
        if (right == null) {
            return 1;
        }
        return left.compareTo(right);
    };

    private final Map<String, String> map;
    private boolean immutable = false;
    private transient String[] sortedKeys;

    public JdkMapAdapterStringMap() {
        this(new HashMap<String, String>());
    }

    public JdkMapAdapterStringMap(final Map<String, String> map) {
        this.map = Objects.requireNonNull(map, "map");
    }

    @Override
    public Map<String, String> toMap() {
        return map;
    }

    private void assertNotFrozen() {
        if (immutable) {
            throw new UnsupportedOperationException(FROZEN);
        }
    }

    @Override
    public boolean containsKey(final String key) {
        return map.containsKey(key);
    }

    @SuppressWarnings("unchecked")
    @Override
    public <V> void forEach(final BiConsumer<String, ? super V> action) {
        final String[] keys = getSortedKeys();
        for (int i = 0; i < keys.length; i++) {
            action.accept(keys[i], (V) map.get(keys[i]));
        }
    }

    @SuppressWarnings("unchecked")
    @Override
    public <V, S> void forEach(final TriConsumer<String, ? super V, S> action, final S state) {
        final String[] keys = getSortedKeys();
        for (int i = 0; i < keys.length; i++) {
            action.accept(keys[i], (V) map.get(keys[i]), state);
        }
    }

    private String[] getSortedKeys() {
        if (sortedKeys == null) {
            sortedKeys = map.keySet().toArray(new String[map.size()]);
            Arrays.sort(sortedKeys, NULL_FIRST_COMPARATOR);
        }
        return sortedKeys;
    }

    @SuppressWarnings("unchecked")
    @Override
    public <V> V getValue(final String key) {
        return (V) map.get(key);
    }

    @Override
    public boolean isEmpty() {
        return map.isEmpty();
    }

    @Override
    public int size() {
        return map.size();
    }

    @Override
    public void clear() {
        if (map.isEmpty()) {
            return;
        }
        assertNotFrozen();
        map.clear();
        sortedKeys = null;
    }

    @Override
    public void freeze() {
        immutable = true;
    }

    @Override
    public boolean isFrozen() {
        return immutable;
    }

    @Override
    public void putAll(final ReadOnlyStringMap source) {
        assertNotFrozen();
        source.forEach(PUT_ALL, map);
        sortedKeys = null;
    }

    private static TriConsumer<String, String, Map<String, String>> PUT_ALL = (key, value, stringStringMap) -> stringStringMap.put(key, value);

    @Override
    public void putValue(final String key, final Object value) {
        assertNotFrozen();
        map.put(key, value == null ? null : String.valueOf(value));
        sortedKeys = null;
    }

    @Override
    public void remove(final String key) {
        if (!map.containsKey(key)) {
            return;
        }
        assertNotFrozen();
        map.remove(key);
        sortedKeys = null;
    }

    @Override
    public String toString() {
        final StringBuilder result = new StringBuilder(map.size() * 13);
        result.append('{');
        final String[] keys = getSortedKeys();
        for (int i = 0; i < keys.length; i++) {
            if (i > 0) {
                result.append(", ");
            }
            result.append(keys[i]).append('=').append(map.get(keys[i]));
        }
        result.append('}');
        return result.toString();
    }

    @Override
    public boolean equals(final Object object) {
        if (object == this) {
            return true;
        }
        if (!(object instanceof JdkMapAdapterStringMap)) {
            return false;
        }
        final JdkMapAdapterStringMap other = (JdkMapAdapterStringMap) object;
        return map.equals(other.map) && immutable == other.immutable;
    }

    @Override
    public int hashCode() {
        return map.hashCode() + (immutable ? 31 : 0);
    }
}

⏎ org/apache/logging/log4j/core/impl/JdkMapAdapterStringMap.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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