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/builder/impl/DefaultConfigurationBuilder.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.builder.impl;

import java.io.IOException;
import java.io.OutputStream;
import java.io.StringReader;
import java.io.StringWriter;
import java.lang.reflect.Constructor;
import java.util.List;
import java.util.Map;
import java.util.concurrent.TimeUnit;

import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamWriter;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.TransformerFactoryConfigurationError;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.ConfigurationException;
import org.apache.logging.log4j.core.config.ConfigurationSource;
import org.apache.logging.log4j.core.config.LoggerConfig;
import org.apache.logging.log4j.core.config.builder.api.AppenderComponentBuilder;
import org.apache.logging.log4j.core.config.builder.api.AppenderRefComponentBuilder;
import org.apache.logging.log4j.core.config.builder.api.Component;
import org.apache.logging.log4j.core.config.builder.api.ComponentBuilder;
import org.apache.logging.log4j.core.config.builder.api.ConfigurationBuilder;
import org.apache.logging.log4j.core.config.builder.api.CustomLevelComponentBuilder;
import org.apache.logging.log4j.core.config.builder.api.FilterComponentBuilder;
import org.apache.logging.log4j.core.config.builder.api.KeyValuePairComponentBuilder;
import org.apache.logging.log4j.core.config.builder.api.LayoutComponentBuilder;
import org.apache.logging.log4j.core.config.builder.api.LoggerComponentBuilder;
import org.apache.logging.log4j.core.config.builder.api.PropertyComponentBuilder;
import org.apache.logging.log4j.core.config.builder.api.RootLoggerComponentBuilder;
import org.apache.logging.log4j.core.config.builder.api.ScriptComponentBuilder;
import org.apache.logging.log4j.core.config.builder.api.ScriptFileComponentBuilder;
import org.apache.logging.log4j.core.util.Throwables;

/**
 * @param <T> The BuiltConfiguration type.
 * @since 2.4
 */
public class DefaultConfigurationBuilder<T extends BuiltConfiguration> implements ConfigurationBuilder<T> {

    private static final String INDENT = "  ";

    private final Component root = new Component();
    private Component loggers;
    private Component appenders;
    private Component filters;
    private Component properties;
    private Component customLevels;
    private Component scripts;
    private final Class<T> clazz;
    private ConfigurationSource source;
    private int monitorInterval;
    private Level level;
    private String verbosity;
    private String destination;
    private String packages;
    private String shutdownFlag;
    private long shutdownTimeoutMillis;
    private String advertiser;
    private LoggerContext loggerContext;
    private String name;

    public static void formatXml(final Source source, final Result result)
        throws TransformerConfigurationException, TransformerFactoryConfigurationError, TransformerException {
        final Transformer transformer = TransformerFactory.newInstance().newTransformer();
        transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", Integer.toString(INDENT.length()));
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
        transformer.transform(source, result);
    }

    @SuppressWarnings("unchecked")
    public DefaultConfigurationBuilder() {
        this((Class<T>) BuiltConfiguration.class);
        root.addAttribute("name", "Built");
    }

    public DefaultConfigurationBuilder(final Class<T> clazz) {
        if (clazz == null) {
            throw new IllegalArgumentException("A Configuration class must be provided");
        }
        this.clazz = clazz;
        final List<Component> components = root.getComponents();
        properties = new Component("Properties");
        components.add(properties);
        scripts = new Component("Scripts");
        components.add(scripts);
        customLevels = new Component("CustomLevels");
        components.add(customLevels);
        filters = new Component("Filters");
        components.add(filters);
        appenders = new Component("Appenders");
        components.add(appenders);
        loggers = new Component("Loggers");
        components.add(loggers);
    }

    protected ConfigurationBuilder<T> add(final Component parent, final ComponentBuilder<?> builder) {
        parent.getComponents().add(builder.build());
        return this;
    }

    @Override
    public ConfigurationBuilder<T> add(final AppenderComponentBuilder builder) {
        return add(appenders, builder);
    }

    @Override
    public ConfigurationBuilder<T> add(final CustomLevelComponentBuilder builder) {
        return add(customLevels, builder);
    }

    @Override
    public ConfigurationBuilder<T> add(final FilterComponentBuilder builder) {
        return add(filters, builder);
    }

    @Override
    public ConfigurationBuilder<T> add(final ScriptComponentBuilder builder) {
        return add(scripts, builder);
    }

    @Override
    public ConfigurationBuilder<T> add(final ScriptFileComponentBuilder builder) {
        return add(scripts, builder);
    }

    @Override
    public ConfigurationBuilder<T> add(final LoggerComponentBuilder builder) {
        return add(loggers, builder);
    }

    @Override
    public ConfigurationBuilder<T> add(final RootLoggerComponentBuilder builder) {
        for (final Component c : loggers.getComponents()) {
            if (c.getPluginType().equals(LoggerConfig.ROOT)) {
                throw new ConfigurationException("Root Logger was previously defined");
            }
        }
        return add(loggers, builder);
    }

    @Override
    public ConfigurationBuilder<T> addProperty(final String key, final String value) {
        properties.addComponent(newComponent(key, "Property", value).build());
        return this;
    }

    @Override
    public T build() {
        return build(true);
    }

    @Override
    public T build(final boolean initialize) {
        T configuration;
        try {
            if (source == null) {
                source = ConfigurationSource.NULL_SOURCE;
            }
            final Constructor<T> constructor = clazz.getConstructor(LoggerContext.class, ConfigurationSource.class, Component.class);
            configuration = constructor.newInstance(loggerContext, source, root);
            configuration.getRootNode().getAttributes().putAll(root.getAttributes());
            if (name != null) {
                configuration.setName(name);
            }
            if (level != null) {
                configuration.getStatusConfiguration().withStatus(level);
            }
            if (verbosity != null) {
                configuration.getStatusConfiguration().withVerbosity(verbosity);
            }
            if (destination != null) {
                configuration.getStatusConfiguration().withDestination(destination);
            }
            if (packages != null) {
                configuration.setPluginPackages(packages);
            }
            if (shutdownFlag != null) {
                configuration.setShutdownHook(shutdownFlag);
            }
            if (shutdownTimeoutMillis > 0) {
                configuration.setShutdownTimeoutMillis(shutdownTimeoutMillis);
            }
            if (advertiser != null) {
                configuration.createAdvertiser(advertiser, source);
            }
            configuration.setMonitorInterval(monitorInterval);
        } catch (final Exception ex) {
            throw new IllegalArgumentException("Invalid Configuration class specified", ex);
        }
        configuration.getStatusConfiguration().initialize();
        if (initialize) {
            configuration.initialize();
        }
        return configuration;
    }

    private String formatXml(String xml)
        throws TransformerConfigurationException, TransformerException, TransformerFactoryConfigurationError {
        final StringWriter writer = new StringWriter();
        formatXml(new StreamSource(new StringReader(xml)), new StreamResult(writer));
        return writer.toString();
    }

    @Override
    public void writeXmlConfiguration(final OutputStream output) throws IOException {
        try {
            final XMLStreamWriter xmlWriter = XMLOutputFactory.newInstance().createXMLStreamWriter(output);
            writeXmlConfiguration(xmlWriter);
            xmlWriter.close();
        } catch (final XMLStreamException e) {
            if (e.getNestedException() instanceof IOException) {
                throw (IOException) e.getNestedException();
            }
            Throwables.rethrow(e);
        }
    }

    @Override
    public String toXmlConfiguration() {
        final StringWriter writer = new StringWriter();
        try {
            final XMLStreamWriter xmlWriter = XMLOutputFactory.newInstance().createXMLStreamWriter(writer);
            writeXmlConfiguration(xmlWriter);
            xmlWriter.close();
            return formatXml(writer.toString());
        } catch (final XMLStreamException | TransformerException e) {
            Throwables.rethrow(e);
        }
        return writer.toString();
    }

    private void writeXmlConfiguration(final XMLStreamWriter xmlWriter) throws XMLStreamException {
        xmlWriter.writeStartDocument();
        xmlWriter.writeStartElement("Configuration");
        if (name != null) {
            xmlWriter.writeAttribute("name", name);
        }
        if (level != null) {
            xmlWriter.writeAttribute("status", level.name());
        }
        if (verbosity != null) {
            xmlWriter.writeAttribute("verbose", verbosity);
        }
        if (destination != null) {
            xmlWriter.writeAttribute("dest", destination);
        }
        if (packages != null) {
            xmlWriter.writeAttribute("packages", packages);
        }
        if (shutdownFlag != null) {
            xmlWriter.writeAttribute("shutdownHook", shutdownFlag);
        }
        if (shutdownTimeoutMillis > 0) {
            xmlWriter.writeAttribute("shutdownTimeout", String.valueOf(shutdownTimeoutMillis));
        }
        if (advertiser != null) {
            xmlWriter.writeAttribute("advertiser", advertiser);
        }
        if (monitorInterval > 0) {
            xmlWriter.writeAttribute("monitorInterval", String.valueOf(monitorInterval));
        }

        writeXmlSection(xmlWriter, properties);
        writeXmlSection(xmlWriter, scripts);
        writeXmlSection(xmlWriter, customLevels);
        if (filters.getComponents().size() == 1) {
            writeXmlComponent(xmlWriter, filters.getComponents().get(0));
        } else if (filters.getComponents().size() > 1) {
            writeXmlSection(xmlWriter, filters);
        }
        writeXmlSection(xmlWriter, appenders);
        writeXmlSection(xmlWriter, loggers);

        xmlWriter.writeEndElement(); // "Configuration"
        xmlWriter.writeEndDocument();
    }

    private void writeXmlSection(final XMLStreamWriter xmlWriter, final Component component) throws XMLStreamException {
        if (!component.getAttributes().isEmpty() || !component.getComponents().isEmpty() || component.getValue() != null) {
            writeXmlComponent(xmlWriter, component);
        }
    }

    private void writeXmlComponent(final XMLStreamWriter xmlWriter, final Component component) throws XMLStreamException {
        if (!component.getComponents().isEmpty() || component.getValue() != null) {
            xmlWriter.writeStartElement(component.getPluginType());
            writeXmlAttributes(xmlWriter, component);
            for (final Component subComponent : component.getComponents()) {
                writeXmlComponent(xmlWriter, subComponent);
            }
            if (component.getValue() != null) {
                xmlWriter.writeCharacters(component.getValue());
            }
            xmlWriter.writeEndElement();
        } else {
            xmlWriter.writeEmptyElement(component.getPluginType());
            writeXmlAttributes(xmlWriter, component);
        }
    }

    private void writeXmlAttributes(final XMLStreamWriter xmlWriter, final Component component) throws XMLStreamException {
        for (final Map.Entry<String, String> attribute : component.getAttributes().entrySet()) {
            xmlWriter.writeAttribute(attribute.getKey(), attribute.getValue());
        }
    }

    @Override
    public ScriptComponentBuilder newScript(final String name, final String language, final String text) {
        return new DefaultScriptComponentBuilder(this, name, language, text);
    }


    @Override
    public ScriptFileComponentBuilder newScriptFile(final String path) {
        return new DefaultScriptFileComponentBuilder(this, path, path);
    }

    @Override
    public ScriptFileComponentBuilder newScriptFile(final String name, final String path) {
        return new DefaultScriptFileComponentBuilder(this, name, path);
    }

    @Override
    public AppenderComponentBuilder newAppender(final String name, final String type) {
        return new DefaultAppenderComponentBuilder(this, name, type);
    }

    @Override
    public AppenderRefComponentBuilder newAppenderRef(final String ref) {
        return new DefaultAppenderRefComponentBuilder(this, ref);
    }

    @Override
    public LoggerComponentBuilder newAsyncLogger(final String name) {
        return new DefaultLoggerComponentBuilder(this, name, null, "AsyncLogger");
    }

    @Override
    public LoggerComponentBuilder newAsyncLogger(final String name, final boolean includeLocation) {
        return new DefaultLoggerComponentBuilder(this, name, null, "AsyncLogger", includeLocation);
    }

    @Override
    public LoggerComponentBuilder newAsyncLogger(final String name, final Level level) {
        return new DefaultLoggerComponentBuilder(this, name, level.toString(), "AsyncLogger");
    }

    @Override
    public LoggerComponentBuilder newAsyncLogger(final String name, final Level level, final boolean includeLocation) {
        return new DefaultLoggerComponentBuilder(this, name, level.toString(), "AsyncLogger", includeLocation);
    }

    @Override
    public LoggerComponentBuilder newAsyncLogger(final String name, final String level) {
        return new DefaultLoggerComponentBuilder(this, name, level, "AsyncLogger");
    }

    @Override
    public LoggerComponentBuilder newAsyncLogger(final String name, final String level, final boolean includeLocation) {
        return new DefaultLoggerComponentBuilder(this, name, level, "AsyncLogger", includeLocation);
    }

    @Override
    public RootLoggerComponentBuilder newAsyncRootLogger() {
        return new DefaultRootLoggerComponentBuilder(this, "AsyncRoot");
    }

    @Override
    public RootLoggerComponentBuilder newAsyncRootLogger(final boolean includeLocation) {
        return new DefaultRootLoggerComponentBuilder(this, null, "AsyncRoot", includeLocation);
    }

    @Override
    public RootLoggerComponentBuilder newAsyncRootLogger(final Level level) {
        return new DefaultRootLoggerComponentBuilder(this, level.toString(), "AsyncRoot");
    }

    @Override
    public RootLoggerComponentBuilder newAsyncRootLogger(final Level level, final boolean includeLocation) {
        return new DefaultRootLoggerComponentBuilder(this, level.toString(), "AsyncRoot", includeLocation);
    }

    @Override
    public RootLoggerComponentBuilder newAsyncRootLogger(final String level) {
        return new DefaultRootLoggerComponentBuilder(this, level, "AsyncRoot");
    }

    @Override
    public RootLoggerComponentBuilder newAsyncRootLogger(final String level, final boolean includeLocation) {
        return new DefaultRootLoggerComponentBuilder(this, level, "AsyncRoot", includeLocation);
    }


    @Override
    public <B extends ComponentBuilder<B>> ComponentBuilder<B> newComponent(final String type) {
        return new DefaultComponentBuilder<>(this, type);
    }

    @Override
    public <B extends ComponentBuilder<B>> ComponentBuilder<B> newComponent(final String name, final String type) {
        return new DefaultComponentBuilder<>(this, name, type);
    }

    @Override
    public <B extends ComponentBuilder<B>> ComponentBuilder<B> newComponent(final String name, final String type,
                                                                            final String value) {
        return new DefaultComponentBuilder<>(this, name, type, value);
    }

    @Override
    public PropertyComponentBuilder newProperty(final String name, final String value) {
        return new DefaultPropertyComponentBuilder(this, name, value);
    }

    @Override
    public KeyValuePairComponentBuilder newKeyValuePair(final String key, final String value) {
        return new DefaultKeyValuePairComponentBuilder(this, key, value);
    }

    @Override
    public CustomLevelComponentBuilder newCustomLevel(final String name, final int level) {
        return new DefaultCustomLevelComponentBuilder(this, name, level);
    }

    @Override
    public FilterComponentBuilder newFilter(final String type, final Filter.Result onMatch,
                                            final Filter.Result onMismatch) {
        return new DefaultFilterComponentBuilder(this, type, onMatch.name(), onMismatch.name());
    }

    @Override
    public FilterComponentBuilder newFilter(final String type, final String onMatch, final String onMismatch) {
        return new DefaultFilterComponentBuilder(this, type, onMatch, onMismatch);
    }

    @Override
    public LayoutComponentBuilder newLayout(final String type) {
        return new DefaultLayoutComponentBuilder(this, type);
    }

    @Override
    public LoggerComponentBuilder newLogger(final String name) {
        return new DefaultLoggerComponentBuilder(this, name, null);
    }

    @Override
    public LoggerComponentBuilder newLogger(final String name, final boolean includeLocation) {
        return new DefaultLoggerComponentBuilder(this, name, null, includeLocation);
    }

    @Override
    public LoggerComponentBuilder newLogger(final String name, final Level level) {
        return new DefaultLoggerComponentBuilder(this, name, level.toString());
    }

    @Override
    public LoggerComponentBuilder newLogger(final String name, final Level level, final boolean includeLocation) {
        return new DefaultLoggerComponentBuilder(this, name, level.toString(), includeLocation);
    }

    @Override
    public LoggerComponentBuilder newLogger(final String name, final String level) {
        return new DefaultLoggerComponentBuilder(this, name, level);
    }

    @Override
    public LoggerComponentBuilder newLogger(final String name, final String level, final boolean includeLocation) {
        return new DefaultLoggerComponentBuilder(this, name, level, includeLocation);
    }

    @Override
    public RootLoggerComponentBuilder newRootLogger() {
        return new DefaultRootLoggerComponentBuilder(this, null);
    }

    @Override
    public RootLoggerComponentBuilder newRootLogger(final boolean includeLocation) {
        return new DefaultRootLoggerComponentBuilder(this, null, includeLocation);
    }

    @Override
    public RootLoggerComponentBuilder newRootLogger(final Level level) {
        return new DefaultRootLoggerComponentBuilder(this, level.toString());
    }

    @Override
    public RootLoggerComponentBuilder newRootLogger(final Level level, final boolean includeLocation) {
        return new DefaultRootLoggerComponentBuilder(this, level.toString(), includeLocation);
    }

    @Override
    public RootLoggerComponentBuilder newRootLogger(final String level) {
        return new DefaultRootLoggerComponentBuilder(this, level);
    }

    @Override
    public RootLoggerComponentBuilder newRootLogger(final String level, final boolean includeLocation) {
        return new DefaultRootLoggerComponentBuilder(this, level, includeLocation);
    }

    @Override
    public ConfigurationBuilder<T> setAdvertiser(final String advertiser) {
        this.advertiser = advertiser;
        return this;
    }

    /**
     * Set the name of the configuration.
     *
     * @param name the name of the {@link Configuration}. By default is {@code "Assembled"}.
     * @return this builder instance
     */
    @Override
    public ConfigurationBuilder<T> setConfigurationName(final String name) {
        this.name = name;
        return this;
    }

    /**
     * Set the ConfigurationSource.
     *
     * @param configurationSource the {@link ConfigurationSource}
     * @return this builder instance
     */
    @Override
    public ConfigurationBuilder<T> setConfigurationSource(final ConfigurationSource configurationSource) {
        source = configurationSource;
        return this;
    }

    @Override
    public ConfigurationBuilder<T> setMonitorInterval(final String intervalSeconds) {
        monitorInterval = Integer.parseInt(intervalSeconds);
        return this;
    }

    @Override
    public ConfigurationBuilder<T> setPackages(final String packages) {
        this.packages = packages;
        return this;
    }

    @Override
    public ConfigurationBuilder<T> setShutdownHook(final String flag) {
        this.shutdownFlag = flag;
        return this;
    }

    @Override
    public ConfigurationBuilder<T> setShutdownTimeout(final long timeout, final TimeUnit timeUnit) {
        this.shutdownTimeoutMillis = timeUnit.toMillis(timeout);
        return this;
    }

    @Override
    public ConfigurationBuilder<T> setStatusLevel(final Level level) {
        this.level = level;
        return this;
    }

    @Override
    public ConfigurationBuilder<T> setVerbosity(final String verbosity) {
        this.verbosity = verbosity;
        return this;
    }

    @Override
    public ConfigurationBuilder<T> setDestination(final String destination) {
        this.destination = destination;
        return this;
    }

    @Override
    public void setLoggerContext(final LoggerContext loggerContext) {
        this.loggerContext = loggerContext;
    }

    @Override
    public ConfigurationBuilder<T> addRootProperty(final String key, final String value) {
        root.getAttributes().put(key, value);
        return this;
    }

}

⏎ org/apache/logging/log4j/core/config/builder/impl/DefaultConfigurationBuilder.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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