Source Code for Apache Log4j Core Implementation

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.

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org/apache/logging/log4j/core/config/plugins/processor/PluginCache.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.processor;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URL;
import java.util.Enumeration;
import java.util.Map;
import java.util.TreeMap;

/**
 *
 */
public class PluginCache {
    private final Map<String, Map<String, PluginEntry>> categories =
        new TreeMap<>();

    /**
     * Returns all categories of plugins in this cache.
     *
     * @return all categories of plugins in this cache.
     * @since 2.1
     */
    public Map<String, Map<String, PluginEntry>> getAllCategories() {
        return categories;
    }

    /**
     * Gets or creates a category of plugins.
     *
     * @param category name of category to look up.
     * @return plugin mapping of names to plugin entries.
     */
    public Map<String, PluginEntry> getCategory(final String category) {
        final String key = category.toLowerCase();
        return categories.computeIfAbsent(key, ignored -> new TreeMap<>());
    }

    /**
     * Stores the plugin cache to a given OutputStream.
     *
     * @param os destination to save cache to.
     * @throws IOException if an I/O exception occurs.
     */
    // NOTE: if this file format is to be changed, the filename should change and this format should still be readable
    public void writeCache(final OutputStream os) throws IOException {
        try (final DataOutputStream out = new DataOutputStream(new BufferedOutputStream(os))) {
            // See PluginManager.readFromCacheFiles for the corresponding decoder. Format may not be changed
            // without breaking existing Log4j2Plugins.dat files.
            out.writeInt(categories.size());
            for (final Map.Entry<String, Map<String, PluginEntry>> category : categories.entrySet()) {
                out.writeUTF(category.getKey());
                final Map<String, PluginEntry> m = category.getValue();
                out.writeInt(m.size());
                for (final Map.Entry<String, PluginEntry> entry : m.entrySet()) {
                    final PluginEntry plugin = entry.getValue();
                    out.writeUTF(plugin.getKey());
                    out.writeUTF(plugin.getClassName());
                    out.writeUTF(plugin.getName());
                    out.writeBoolean(plugin.isPrintable());
                    out.writeBoolean(plugin.isDefer());
                }
            }
        }
    }

    /**
     * Loads and merges all the Log4j plugin cache files specified. Usually, this is obtained via a ClassLoader.
     *
     * @param resources URLs to all the desired plugin cache files to load.
     * @throws IOException if an I/O exception occurs.
     */
    public void loadCacheFiles(final Enumeration<URL> resources) throws IOException {
        categories.clear();
        while (resources.hasMoreElements()) {
            final URL url = resources.nextElement();
            try (final DataInputStream in = new DataInputStream(new BufferedInputStream(url.openStream()))) {
                final int count = in.readInt();
                for (int i = 0; i < count; i++) {
                    final String category = in.readUTF();
                    final Map<String, PluginEntry> m = getCategory(category);
                    final int entries = in.readInt();
                    for (int j = 0; j < entries; j++) {
                        // Must always read all parts of the entry, even if not adding, so that the stream progresses
                        final String key = in.readUTF();
                        final String className = in.readUTF();
                        final String name = in.readUTF();
                        final boolean printable = in.readBoolean();
                        final boolean defer = in.readBoolean();
                        m.computeIfAbsent(key, k -> {
                            final PluginEntry entry = new PluginEntry();
                            entry.setKey(k);
                            entry.setClassName(className);
                            entry.setName(name);
                            entry.setPrintable(printable);
                            entry.setDefer(defer);
                            entry.setCategory(category);
                            return entry;
                        });
                    }
                }
            }
        }
    }

    /**
     * Gets the number of plugin categories registered.
     *
     * @return number of plugin categories in cache.
     */
    public int size() {
        return categories.size();
    }
}

org/apache/logging/log4j/core/config/plugins/processor/PluginCache.java

 

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2015-11-03, 51064👍, 0💬