How to send java.util.logging to log4j?

We use SLF4J on our current project and it's worked very well for us. SLF4J is written by Ceki Gülcü, the creator of Log4J, and he's done a really great job. In our code we use the SLF4J logging APIs directly, and we configure SLF4J so that calls from the Jakarta Commons Logging (JCL), java.util.logging (JUL), and Log4J APIs are all bridged to the SLF4J APIs. We need to do that because like you we use third party (open source) libraries that have chosen different logging APIs.

On the bottom of SLF4J, you configure it to use a particular logger implementation. It comes with an internal, or "simple" logger, and you can override this with Log4J, JUL, or Logback. Configuration is all done simply by dropping in different jar files in your classpath.

Originally, we used the Logback implementation, also written by Ceki Gülcü. This is very powerful. However, we then decided to deploy our application to the Glassfish Java EE application server, whose log viewer expects JUL-formatted messages. So today I switched from Logback to JUL, and in just a few minutes I replaced two Logback jars with an SLF4J jar that connects it to the JUL implementation.

So like @overthink, I would heartily recommend using SLF4J in your setup.

There is a simpler alternative than SLF4J to bridge JUL with log4j, see http://people.apache.org/~psmith/logging.apache.org/sandbox/jul-log4j-bridge/examples.html

You just have to put the jul-log4j-bridge on the classpath and add a system property:

-Djava.util.logging.manager=org.apache.logging.julbridge.JULBridgeLogManager

jul-log4j-bridge is not in Maven Central and can be fetched from this repository:

<repository>
  <id>psmith</id>
  <url>http://people.apache.org/~psmith/logging.apache.org/repo</url>
  <releases>
    <enabled>false</enabled>
  </releases>
</repository>

and then used with:

<dependency>
  <groupId>org.apache.logging</groupId>
  <artifactId>apache-jul-log4j-bridge</artifactId>
  <version>1.0.0-SNAPSHOT</version>
  <scope>test</scope>
  <exclusions>
    <exclusion>
      <groupId>log4j</groupId>
      <artifactId>apache-log4j-component</artifactId>
    </exclusion>
  </exclusions>
</dependency>

It's also possible to rebuild it from sources with the following steps:

1. svn co http://svn.apache.org/repos/asf/logging/sandbox/jul-to-log4j-bridge/
2. edit pom.xml, replace the dependency on log4j:log4j:1.2.15 with log4j:apache-log4j-extras:1.2.17 and remove the dependency on apache-log4j-component
3. mvn package

One approach I have used successfully is to use slf4j as my primary logging API. I then have slf4j bind to log4j. 3rd party dependencies using other frameworks (like JUL) can be bridged to slf4j.