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/net/DatagramOutputStream.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.net;

import java.io.IOException;
import java.io.OutputStream;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.appender.AppenderLoggingException;
import org.apache.logging.log4j.status.StatusLogger;

/**
 * OutputStream for UDP connections.
 */
public class DatagramOutputStream extends OutputStream {

    /**
     * Allow subclasses access to the status logger without creating another instance.
     */
    protected static final Logger LOGGER = StatusLogger.getLogger();

    private static final int SHIFT_1 = 8;
    private static final int SHIFT_2 = 16;
    private static final int SHIFT_3 = 24;

    private DatagramSocket datagramSocket;
    private final InetAddress inetAddress;
    private final int port;

    private byte[] data;

    private final byte[] header;
    private final byte[] footer;

    /**
     * The Constructor.
     * @param host The host to connect to.
     * @param port The port on the host.
     */
    public DatagramOutputStream(final String host, final int port, final byte[] header, final byte[] footer) {
        this.port = port;
        this.header = header;
        this.footer = footer;
        try {
            inetAddress = InetAddress.getByName(host);
        } catch (final UnknownHostException ex) {
            final String msg = "Could not find host " + host;
            LOGGER.error(msg, ex);
            throw new AppenderLoggingException(msg, ex);
        }

        try {
            datagramSocket = new DatagramSocket();
        } catch (final SocketException ex) {
            final String msg = "Could not instantiate DatagramSocket to " + host;
            LOGGER.error(msg, ex);
            throw new AppenderLoggingException(msg, ex);
        }
    }

    @Override
    public synchronized void write(final byte[] bytes, final int offset, final int length) throws IOException {
        copy(bytes, offset, length);
    }

    @Override
    public synchronized void write(final int i) throws IOException {
        copy(new byte[] {(byte) (i >>> SHIFT_3), (byte) (i >>> SHIFT_2), (byte) (i >>> SHIFT_1), (byte) i}, 0, 4);
    }

    @Override
    public synchronized void write(final byte[] bytes) throws IOException {
        copy(bytes, 0, bytes.length);
    }

    @Override
    public synchronized void flush() throws IOException {
        try {
            if (this.data != null && this.datagramSocket != null && this.inetAddress != null) {
                if (footer != null) {
                    copy(footer, 0, footer.length);
                }
                final DatagramPacket packet = new DatagramPacket(data, data.length, inetAddress, port);
                datagramSocket.send(packet);
            }
        } finally {
            data = null;
            if (header != null) {
                copy(header, 0, header.length);
            }
        }
    }

    @Override
    public synchronized void close() throws IOException {
        if (datagramSocket != null) {
            if (data != null) {
                flush();
            }
            datagramSocket.close();
            datagramSocket = null;
        }
    }

    private void copy(final byte[] bytes, final int offset, final int length) {
        final int index = data == null ? 0 : data.length;
        final byte[] copy = new byte[length + index];
        if (data != null) {
            System.arraycopy(data, 0, copy, 0, data.length);
        }
        System.arraycopy(bytes, offset, copy, index, length);
        data = copy;
    }
}

⏎ org/apache/logging/log4j/core/net/DatagramOutputStream.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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