How can I get application libraries (jarNames) on java web servers like Tomcat and WAS?

Question

I need to get jarNames of the libraries used from my web application on Tomcat and Websphere servers.

I have this code:

public void libs(ActionEvent e){

    System.getProperty("java.class.path");

    try {
            Field ucp = this.getClass().getClassLoader().getClass()
                        .getSuperclass().getDeclaredField("ucp");

            ucp.setAccessible(true);

            Object valueUcp = ucp.get(this.getClass().getClassLoader());

            Field loaders = valueUcp.getClass().getDeclaredField("path");

            loaders.setAccessible(true);

            ArrayList collection = (ArrayList) loaders.get(valueUcp);

    } catch (Exception e) {

        e.printStackTrace();

    }

}

It works on Tomcat, but not on websphere.

PS. Sorry my bad english.

Answer 1

If there is no need to get it programatically this is what i would suggest. Use the class loader viewer in the console and that gives you the required information.

I would suggest you run your automated test cases in a test environment and then view this and you would be able to see all the classes that were loaded by the runtime to service your web application needs.

I agree with fnt on what is the need to write such stuff? If you are in a troubleshooting phase and trying to find some sort NCDF or CNF Exceptions then the approach of using Class Loader Viewer would be of good help. Also looking at the verbose class loader outputs in the native_stderr.log will be of immense help during troubleshooting activities.

HTH Manglu

Answer 2

There is no portable API to get this information. On WebSphere Application Server, ClassLoader.toString typically contains the full class path for diagnostic purposes, but I would definitely not recommend attempting to "parse" the output. I wouldn't recommend using reflection on Tomcat either: it might work for current Tomcat versions, but there's no guarantee the class loader implementation won't change and break your application.