Apache Log4j provides the interface that applications should code to and provides the adapter components required for implementers to create a logging implementation.

Bytecode (Java 1.4) for Apache Log4j is provided in a JAR file like log4j-1.2.17.jar.

Source Code files for Apache Log4j are provided in both binary packge like log4j-1.2.17.zip and source package like log4j-1.2.17-sources.zip. You can download them at Apache Log4j Website.

You can also browse Source Code files for Apache Log4j 1.2.17 below.

⏎ org/apache/log4j/spi/NOPLoggerRepository.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.log4j.spi;

import org.apache.log4j.Level;
import org.apache.log4j.Category;
import org.apache.log4j.Logger;
import org.apache.log4j.Appender;

import java.util.Enumeration;
import java.util.Vector;

/**
 *  No-operation implementation of LoggerRepository which is used when
 *  LogManager.repositorySelector is erroneously nulled during class reloading.
 *  @since 1.2.15
 */
public final class NOPLoggerRepository implements LoggerRepository {
    /**
     * {@inheritDoc}
    */
    public void addHierarchyEventListener(final HierarchyEventListener listener) {
    }

    /**
     * {@inheritDoc}
     */
    public boolean isDisabled(final int level) {
        return true;
    }

    /**
     * {@inheritDoc}
     */
    public void setThreshold(final Level level) {
    }

    /**
     * {@inheritDoc}
     */
    public void setThreshold(final String val) {
    }

    /**
     * {@inheritDoc}
     */
    public void emitNoAppenderWarning(final Category cat) {
    }

    /**
     * {@inheritDoc}
     */
    public Level getThreshold() {
        return Level.OFF;
    }

    /**
     * {@inheritDoc}
     */
    public Logger getLogger(final String name) {
        return new NOPLogger(this, name);
    }

    /**
     * {@inheritDoc}
     */
    public Logger getLogger(final String name, final LoggerFactory factory) {
        return new NOPLogger(this, name);
    }

    /**
     * {@inheritDoc}
     */
    public Logger getRootLogger() {
        return new NOPLogger(this, "root");
    }

    /**
     * {@inheritDoc}
     */
    public Logger exists(final String name) {
        return null;
    }

    /**
     * {@inheritDoc}
     */
    public void shutdown() {
    }

    /**
     * {@inheritDoc}
     */
    public Enumeration getCurrentLoggers() {
        return new Vector().elements();
    }

    /**
     * {@inheritDoc}
     */
    public Enumeration getCurrentCategories() {
        return getCurrentLoggers();
    }


    /**
     * {@inheritDoc}
     */
    public  void fireAddAppenderEvent(Category logger, Appender appender) {
    }

    /**
     * {@inheritDoc}
     */
    public void resetConfiguration() {
    }
}

⏎ org/apache/log4j/spi/NOPLoggerRepository.java

Or download all of them as a single archive file:

File name: log4j-1.2.17-sources.jar
File size: 481200 bytes
Release date: 2012-05-06
Download 

⇒ Download and Install apache-log4j-1.2.15.zip

⇐ Download and Install log4j-1.2.17.zip

⇑ Downloading Apache Log4j 1.x JAR Packages

⇑⇑ FAQ for Apache Log4j