Reading my own Jar's Manifest

Question

I need to read the Manifest file, which delivered my class, but when I use:

getClass().getClassLoader().getResources(...)

I get the MANIFEST from the first .jar loaded into the Java Runtime.
My app will be running from an applet or a webstart,
so I will not have access to my own .jar file, I guess.

I actually want to read the Export-package attribute from the .jar which started the Felix OSGi, so I can expose those packages to Felix. Any ideas?

Answer 1

You can do one of two things:

1. Call getResources() and iterate through the returned collection of URLs, reading them as manifests until you find yours:

    Enumeration<URL> resources = getClass().getClassLoader()
      .getResources("META-INF/MANIFEST.MF");
    while (resources.hasMoreElements()) {
        try {
          Manifest manifest = new Manifest(resources.nextElement().openStream());
          // If the line above leads to <null> manifest Attributes try from JarInputStream:
          // Manifest manifest = resources.nextElement().openStream().getManifest();
   
          // check that this is your manifest and do what you need or get the next one
          ...
        } catch (IOException E) {
          // handle
        }
    }
   

2. You can try checking whether getClass().getClassLoader() is an instance of java.net.URLClassLoader. Majority of Sun classloaders are, including AppletClassLoader. You can then cast it and call findResource() which has been known - for applets, at least - to return the needed manifest directly:

    URLClassLoader cl = (URLClassLoader) getClass().getClassLoader();
    try {
      URL url = cl.findResource("META-INF/MANIFEST.MF");
      Manifest manifest = new Manifest(url.openStream());
      // do stuff with it
      ...
    } catch (IOException E) {
      // handle
    }