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/rewrite/RewritePolicy.java

package org.apache.log4j.rewrite;

import org.apache.log4j.spi.LoggingEvent;

/*
* 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.
*/

/**
 * This interface is implemented to provide a rewrite
 * strategy for RewriteAppender.  RewriteAppender will
 * call the rewrite method with a source logging event.
 * The strategy may return that event, create a new event
 * or return null to suppress the logging request.
 */
public interface RewritePolicy {
    /**
     * Rewrite a logging event.
     * @param source a logging event that may be returned or
     * used to create a new logging event.
     * @return a logging event or null to suppress processing.
     */
    LoggingEvent rewrite(final LoggingEvent source);
}

⏎ org/apache/log4j/rewrite/RewritePolicy.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