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/HttpWatcher.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 java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAliases;
import org.apache.logging.log4j.core.net.UrlConnectionFactory;
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.AbstractWatcher;
import org.apache.logging.log4j.core.util.Source;
import org.apache.logging.log4j.core.util.Watcher;
import org.apache.logging.log4j.status.StatusLogger;

/**
 *
 */
@Plugin(name = "http", category = Watcher.CATEGORY, elementType = Watcher.ELEMENT_TYPE, printObject = true)
@PluginAliases("https")
public class HttpWatcher extends AbstractWatcher {

    private Logger LOGGER = StatusLogger.getLogger();

    private SslConfiguration sslConfiguration;
    private URL url;
    private volatile long lastModifiedMillis;
    private static final int NOT_MODIFIED = 304;
    private static final int OK = 200;
    private static final int BUF_SIZE = 1024;
    private static final String HTTP = "http";
    private static final String HTTPS = "https";

    public HttpWatcher(final Configuration configuration, final Reconfigurable reconfigurable,
        final List<ConfigurationListener> configurationListeners, long lastModifiedMillis) {
        super(configuration, reconfigurable, configurationListeners);
        sslConfiguration = SslConfigurationFactory.getSslConfiguration();
        this.lastModifiedMillis = lastModifiedMillis;
    }

    @Override
    public long getLastModified() {
        return lastModifiedMillis;
    }

    @Override
    public boolean isModified() {
        return refreshConfiguration();
    }

    @Override
    public void watching(Source source) {
        if (!source.getURI().getScheme().equals(HTTP) && !source.getURI().getScheme().equals(HTTPS)) {
            throw new IllegalArgumentException(
                "HttpWatcher requires a url using the HTTP or HTTPS protocol, not " + source.getURI().getScheme());
        }
        try {
            url = source.getURI().toURL();
        } catch (MalformedURLException ex) {
            throw new IllegalArgumentException("Invalid URL for HttpWatcher " + source.getURI(), ex);
        }
        super.watching(source);
    }

    @Override
    public Watcher newWatcher(Reconfigurable reconfigurable, List<ConfigurationListener> listeners,
        long lastModifiedMillis) {
        HttpWatcher watcher = new HttpWatcher(getConfiguration(), reconfigurable, listeners, lastModifiedMillis);
        if (getSource() != null) {
            watcher.watching(getSource());
        }
        return watcher;
    }

    private boolean refreshConfiguration() {
        try {
            final HttpURLConnection urlConnection = UrlConnectionFactory.createConnection(url, lastModifiedMillis,
                sslConfiguration);
            urlConnection.connect();

            try {
                int code = urlConnection.getResponseCode();
                switch (code) {
                    case NOT_MODIFIED: {
                        LOGGER.debug("Configuration Not Modified");
                        return false;
                    }
                    case OK: {
                        try (InputStream is = urlConnection.getInputStream()) {
                            ConfigurationSource configSource = getConfiguration().getConfigurationSource();
                            configSource.setData(readStream(is));
                            lastModifiedMillis = urlConnection.getLastModified();
                            configSource.setModifiedMillis(lastModifiedMillis);
                            LOGGER.debug("Content was modified for {}", url.toString());
                            return true;
                        } catch (final IOException e) {
                            try (InputStream es = urlConnection.getErrorStream()) {
                                LOGGER.info("Error accessing configuration at {}: {}", url, readStream(es));
                            } catch (final IOException ioe) {
                                LOGGER.error("Error accessing configuration at {}: {}", url, e.getMessage());
                            }
                            return false;
                        }
                    }
                    default: {
                        if (code < 0) {
                            LOGGER.info("Invalid response code returned");
                        } else {
                            LOGGER.info("Unexpected response code returned {}", code);
                        }
                        return false;
                    }
                }
            } catch (final IOException ioe) {
                LOGGER.error("Error accessing configuration at {}: {}", url, ioe.getMessage());
            }
        } catch (final IOException ioe) {
            LOGGER.error("Error connecting to configuration at {}: {}", url, ioe.getMessage());
        }
        return false;
    }

    private byte[] readStream(InputStream is) throws IOException {
        ByteArrayOutputStream result = new ByteArrayOutputStream();
        byte[] buffer = new byte[BUF_SIZE];
        int length;
        while ((length = is.read(buffer)) != -1) {
            result.write(buffer, 0, length);
        }
        return result.toByteArray();
    }
}

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