Eclipse PDE and log4j.properties?

Question

I have created an eclipse PDE project and have added log4j as a dependency using the slf4j-api and slf4j.log4j12 bundles. In a class I have created the logger:

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MyTest {

  private static final Logger logger = LoggerFactory.getLogger(MyTest.class
      .getName());

  public void tt() {
    logger.info("log-test");

  }

}

but when I run the PDE project using an OSGI launch configuration I get the warnings:

log4j:WARN No appenders could be found for logger (loggin_test.MyTest).
log4j:WARN Please initialize the log4j system properly.

based on this info:

http://jaikiran.wordpress.com/2006/07/05/i-get-log4jwarn-no-appenders-could-be-found-for-logger-message-2/

I need to put the log4j.properties in the PDE classpath. I have tried to put it in the root of the PDE project and add:

source.. = src/
output.. = bin/
bin.includes = META-INF/,\
               .,\
               log4j.properties

to the build.properties pane. But I still get the same warning. Where do I put the log4j.properties file in a PDE project?

EDIT: I have also tried adding it to the /src folder but it does not help.

Answer 1

AFAIK, you still need the Log4j JAR, since SLF4J is just a wrapper around it. Download the JAR from the Apache web site, add it to your build path and it should work just fine.

Answer 2

You've hit your first resource visibility problem with OSGi. Remember that in OSGi bundles must explicitly define their dependencies. Your problem is that your bundle defines a log4j property file, but it's the log4j bundle that must read it. But the log4j bundle doesn't know anything about your bundle (and nor should it).

Here's 2 solutions to the problem:

1. Use Eclipse's buddy mechanism
2. Put the log4j property file in an OSGi fragment and host it on the log4j bundle

Option 2 is a better solution, but if you find option 1 easier then go with that.

Answer 3

I got the same problem. Adding the folder containing log4j.xml to Project Build Path is not enough (why not?). Anyway, besides the reason for that (maybe eclipse gurus can answer that for us) I solved my problem adding the folder containing log4j.xml to the eclipse "Run configuration".

After you try to run your Standalone App for the first time and get the annoying "No appenders could be found for logger" message, follow the steps bellow:

1. Go to Menu "Run" > "Run Configurations"
2. Your main class should appear somewhere in the left tree. Probably under "Java Application". So select it
3. Select "Classpath" tab, select "User Entries" and click "Advanced" button.
4. On "Advanced Options" pop-up window, select "Add Folders", click "OK" button.
5. On "Folder Selection" pop-up, navigate to your folder where log4j.xml is located and click "OK"btn.
6. Click "Run" button... and... Finally!