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/ConfigurationSource.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;

import javax.net.ssl.HttpsURLConnection;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Objects;

import org.apache.logging.log4j.core.net.UrlConnectionFactory;
import org.apache.logging.log4j.core.net.ssl.LaxHostnameVerifier;
import org.apache.logging.log4j.core.net.ssl.SslConfiguration;
import org.apache.logging.log4j.core.net.ssl.SslConfigurationFactory;
import org.apache.logging.log4j.core.util.AuthorizationProvider;
import org.apache.logging.log4j.core.util.FileUtils;
import org.apache.logging.log4j.core.util.Loader;
import org.apache.logging.log4j.core.util.Source;
import org.apache.logging.log4j.util.LoaderUtil;
import org.apache.logging.log4j.util.PropertiesUtil;

/**
 * Represents the source for the logging configuration.
 */
public class ConfigurationSource {

    /** Empty byte array singleton. */
    private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];

    /**
     * ConfigurationSource to use with Configurations that do not require a "real" configuration source.
     */
    public static final ConfigurationSource NULL_SOURCE = new ConfigurationSource(EMPTY_BYTE_ARRAY, null, 0);

    /**
     * ConfigurationSource to use with {@link org.apache.logging.log4j.core.config.composite.CompositeConfiguration}.
     */
    public static final ConfigurationSource COMPOSITE_SOURCE = new ConfigurationSource(EMPTY_BYTE_ARRAY, null, 0);
    private static final String HTTPS = "https";

    private final File file;
    private final URL url;
    private final String location;
    private final InputStream stream;
    private volatile byte[] data;
    private volatile Source source;
    private final long lastModified;
    // Set when the configuration has been updated so reset can use it for the next lastModified timestamp.
    private volatile long modifiedMillis;

    /**
     * Constructs a new {@code ConfigurationSource} with the specified input stream that originated from the specified
     * file.
     *
     * @param stream the input stream
     * @param file the file where the input stream originated
     */
    public ConfigurationSource(final InputStream stream, final File file) {
        this.stream = Objects.requireNonNull(stream, "stream is null");
        this.file = Objects.requireNonNull(file, "file is null");
        this.location = file.getAbsolutePath();
        this.url = null;
        this.data = null;
        long modified = 0;
        try {
            modified = file.lastModified();
        } catch (Exception ex) {
            // There is a problem with the file. It will be handled somewhere else.
        }
        this.lastModified = modified;
    }

    /**
     * Constructs a new {@code ConfigurationSource} with the specified input stream that originated from the specified
     * url.
     *
     * @param stream the input stream
     * @param url the URL where the input stream originated
     */
    public ConfigurationSource(final InputStream stream, final URL url) {
        this.stream = Objects.requireNonNull(stream, "stream is null");
        this.url = Objects.requireNonNull(url, "URL is null");
        this.location = url.toString();
        this.file = null;
        this.data = null;
        this.lastModified = 0;
    }

    /**
     * Constructs a new {@code ConfigurationSource} with the specified input stream that originated from the specified
     * url.
     *
     * @param stream the input stream
     * @param url the URL where the input stream originated
     * @param lastModified when the source was last modified.
     */
    public ConfigurationSource(final InputStream stream, final URL url, long lastModified) {
        this.stream = Objects.requireNonNull(stream, "stream is null");
        this.url = Objects.requireNonNull(url, "URL is null");
        this.location = url.toString();
        this.file = null;
        this.data = null;
        this.lastModified = lastModified;
    }

    /**
     * Constructs a new {@code ConfigurationSource} with the specified input stream. Since the stream is the only source
     * of data, this constructor makes a copy of the stream contents.
     *
     * @param stream the input stream
     * @throws IOException if an exception occurred reading from the specified stream
     */
    public ConfigurationSource(final InputStream stream) throws IOException {
        this(toByteArray(stream), null, 0);
    }

    public ConfigurationSource(final Source source, final byte[] data, long lastModified) throws IOException {
        Objects.requireNonNull(source, "source is null");
        this.data = Objects.requireNonNull(data, "data is null");
        this.stream = new ByteArrayInputStream(data);
        this.file = source.getFile();
        this.url = source.getURI().toURL();
        this.location = source.getLocation();
        this.lastModified = lastModified;
    }

    private ConfigurationSource(final byte[] data, final URL url, long lastModified) {
        this.data = Objects.requireNonNull(data, "data is null");
        this.stream = new ByteArrayInputStream(data);
        this.file = null;
        this.url = url;
        this.location = null;
        this.lastModified = lastModified;
        if ( url == null ) {
        	this.data = data;
        }
    }

    /**
     * Returns the contents of the specified {@code InputStream} as a byte array.
     *
     * @param inputStream the stream to read
     * @return the contents of the specified stream
     * @throws IOException if a problem occurred reading from the stream
     */
    private static byte[] toByteArray(final InputStream inputStream) throws IOException {
        final int buffSize = Math.max(4096, inputStream.available());
        final ByteArrayOutputStream contents = new ByteArrayOutputStream(buffSize);
        final byte[] buff = new byte[buffSize];

        int length = inputStream.read(buff);
        while (length > 0) {
            contents.write(buff, 0, length);
            length = inputStream.read(buff);
        }
        return contents.toByteArray();
    }

    /**
     * Returns the file configuration source, or {@code null} if this configuration source is based on an URL or has
     * neither a file nor an URL.
     *
     * @return the configuration source file, or {@code null}
     */
    public File getFile() {
        return file;
    }

    /**
     * Returns the configuration source URL, or {@code null} if this configuration source is based on a file or has
     * neither a file nor an URL.
     *
     * @return the configuration source URL, or {@code null}
     */
    public URL getURL() {
        return url;
    }

    public void setSource(Source source) {
        this.source = source;
    }

    public void setData(byte[] data) {
        this.data = data;
    }

    public void setModifiedMillis(long modifiedMillis) {
        this.modifiedMillis = modifiedMillis;
    }

    /**
     * Returns a URI representing the configuration resource or null if it cannot be determined.
     * @return The URI.
     */
    public URI getURI() {
        URI sourceURI = null;
        if (url != null) {
            try {
                sourceURI = url.toURI();
            } catch (final URISyntaxException ex) {
                    /* Ignore the exception */
            }
        }
        if (sourceURI == null && file != null) {
            sourceURI = file.toURI();
        }
        if (sourceURI == null && location != null) {
            try {
                sourceURI = new URI(location);
            } catch (final URISyntaxException ex) {
                // Assume the scheme was missing.
                try {
                    sourceURI = new URI("file://" + location);
                } catch (final URISyntaxException uriEx) {
                    /* Ignore the exception */
                }
            }
        }
        return sourceURI;
    }

    /**
     * Returns the time the resource was last modified or 0 if it is not available.
     * @return the last modified time of the resource.
     */
    public long getLastModified() {
        return lastModified;
    }

    /**
     * Returns a string describing the configuration source file or URL, or {@code null} if this configuration source
     * has neither a file nor an URL.
     *
     * @return a string describing the configuration source file or URL, or {@code null}
     */
    public String getLocation() {
        return location;
    }

    /**
     * Returns the input stream that this configuration source was constructed with.
     *
     * @return the input stream that this configuration source was constructed with.
     */
    public InputStream getInputStream() {
        return stream;
    }

    /**
     * Returns a new {@code ConfigurationSource} whose input stream is reset to the beginning.
     *
     * @return a new {@code ConfigurationSource}
     * @throws IOException if a problem occurred while opening the new input stream
     */
    public ConfigurationSource resetInputStream() throws IOException {
        if (source != null) {
            return new ConfigurationSource(source, data, this.lastModified);
        } else if (file != null) {
            return new ConfigurationSource(new FileInputStream(file), file);
        } else if (url != null && data != null) {
            // Creates a ConfigurationSource without accessing the URL since the data was provided.
            return new ConfigurationSource(data, url, modifiedMillis == 0 ? lastModified : modifiedMillis);
        } else if (url != null) {
            return fromUri(getURI());
        } else if (data != null) {
            return new ConfigurationSource(data, null, lastModified);
        }
        return null;
    }

    @Override
    public String toString() {
        if (location != null) {
            return location;
        }
        if (this == NULL_SOURCE) {
            return "NULL_SOURCE";
        }
        final int length = data == null ? -1 : data.length;
        return "stream (" + length + " bytes, unknown location)";
    }

    /**
     * Loads the configuration from a URI.
     * @param configLocation A URI representing the location of the configuration.
     * @return The ConfigurationSource for the configuration.
     */
    public static ConfigurationSource fromUri(final URI configLocation) {
        final File configFile = FileUtils.fileFromUri(configLocation);
        if (configFile != null && configFile.exists() && configFile.canRead()) {
            try {
                return new ConfigurationSource(new FileInputStream(configFile), configFile);
            } catch (final FileNotFoundException ex) {
                ConfigurationFactory.LOGGER.error("Cannot locate file {}", configLocation.getPath(), ex);
            }
        }
        if (ConfigurationFactory.isClassLoaderUri(configLocation)) {
            final ClassLoader loader = LoaderUtil.getThreadContextClassLoader();
            final String path = ConfigurationFactory.extractClassLoaderUriPath(configLocation);
            return fromResource(path, loader);
        }
        if (!configLocation.isAbsolute()) { // LOG4J2-704 avoid confusing error message thrown by uri.toURL()
            ConfigurationFactory.LOGGER.error("File not found in file system or classpath: {}", configLocation.toString());
            return null;
        }
        try {
            URL url = configLocation.toURL();
            URLConnection urlConnection = UrlConnectionFactory.createConnection(url);
            InputStream is = urlConnection.getInputStream();
            long lastModified = urlConnection.getLastModified();
            return new ConfigurationSource(is, configLocation.toURL(), lastModified);
        } catch (final FileNotFoundException ex) {
            ConfigurationFactory.LOGGER.warn("Could not locate file {}", configLocation.toString());
        } catch (final MalformedURLException ex) {
            ConfigurationFactory.LOGGER.error("Invalid URL {}", configLocation.toString(), ex);
        } catch (final Exception ex) {
            ConfigurationFactory.LOGGER.error("Unable to access {}", configLocation.toString(), ex);
        }
        return null;
    }

    /**
     * Retrieves the configuration via the ClassLoader.
     * @param resource The resource to load.
     * @param loader The default ClassLoader to use.
     * @return The ConfigurationSource for the configuration.
     */
    public static ConfigurationSource fromResource(final String resource, final ClassLoader loader) {
        final URL url = Loader.getResource(resource, loader);
        if (url == null) {
            return null;
        }
        return getConfigurationSource(url);
    }

    private static ConfigurationSource getConfigurationSource(URL url) {
        try {
            URLConnection urlConnection = url.openConnection();
            AuthorizationProvider provider = ConfigurationFactory.authorizationProvider(PropertiesUtil.getProperties());
            provider.addAuthorization(urlConnection);
            if (url.getProtocol().equals(HTTPS)) {
                SslConfiguration sslConfiguration = SslConfigurationFactory.getSslConfiguration();
                if (sslConfiguration != null) {
                    ((HttpsURLConnection) urlConnection).setSSLSocketFactory(sslConfiguration.getSslSocketFactory());
                    if (!sslConfiguration.isVerifyHostName()) {
                        ((HttpsURLConnection) urlConnection).setHostnameVerifier(LaxHostnameVerifier.INSTANCE);
                    }
                }
            }
            File file = FileUtils.fileFromUri(url.toURI());
            try {
                if (file != null) {
                    return new ConfigurationSource(urlConnection.getInputStream(), FileUtils.fileFromUri(url.toURI()));
                } else {
                    return new ConfigurationSource(urlConnection.getInputStream(), url, urlConnection.getLastModified());
                }
            } catch (FileNotFoundException ex) {
                ConfigurationFactory.LOGGER.info("Unable to locate file {}, ignoring.", url.toString());
                return null;
            }
        } catch (IOException | URISyntaxException ex) {
            ConfigurationFactory.LOGGER.warn("Error accessing {} due to {}, ignoring.", url.toString(),
                    ex.getMessage());
            return null;
        }
    }
}

⏎ org/apache/logging/log4j/core/config/ConfigurationSource.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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