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/SimpleLayout.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;

import org.apache.log4j.spi.LoggingEvent;

/**
   SimpleLayout consists of the level of the log statement,
   followed by " - " and then the log message itself. For example,

   <pre>
           DEBUG - Hello world
   </pre>

   <p>
   @author Ceki G&uuml;lc&uuml;
   @since version 0.7.0

   <p>{@link PatternLayout} offers a much more powerful alternative.
*/
public class SimpleLayout extends Layout {

  StringBuffer sbuf = new StringBuffer(128);

  public SimpleLayout() {
  }

  public
  void activateOptions() {
  }
  
  /**
     Returns the log statement in a format consisting of the
     <code>level</code>, followed by " - " and then the
     <code>message</code>. For example, <pre> INFO - "A message"
     </pre>

     <p>The <code>category</code> parameter is ignored.
     <p>
     @return A byte array in SimpleLayout format.
    */
  public
  String format(LoggingEvent event) {

    sbuf.setLength(0);
    sbuf.append(event.getLevel().toString());
    sbuf.append(" - ");
    sbuf.append(event.getRenderedMessage());
    sbuf.append(LINE_SEP);
    return sbuf.toString();
  }

/**
     The SimpleLayout does not handle the throwable contained within
     {@link LoggingEvent LoggingEvents}. Thus, it returns
     <code>true</code>.

     @since version 0.8.4 */
  public
  boolean ignoresThrowable() {
    return true;
  }
}

⏎ org/apache/log4j/SimpleLayout.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