Reading my own Jar's Manifest

Viewed 138437

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?

13 Answers

A simpler way to do this is to use getPackage(). For example, to get Implementation-Version:

Application.class.getPackage().getImplementationVersion()

I have this weird solution that runs war applications in a embedded Jetty server but these apps need also to run on standard Tomcat servers, and we have some special properties in the manfest.

The problem was that when in Tomcat, the manifest could be read, but when in jetty, a random manifest was picked up (which missed the special properties)

Based on Alex Konshin's answer, I came up with the following solution (the inputstream is then used in a Manifest class):

private static InputStream getWarManifestInputStreamFromClassJar(Class<?> cl ) {
    InputStream inputStream = null;
    try {
        URLClassLoader classLoader = (URLClassLoader)cl.getClassLoader();
        String classFilePath = cl.getName().replace('.','/')+".class";
        URL classUrl = classLoader.getResource(classFilePath);
        if ( classUrl==null ) return null;
        String classUri = classUrl.toString();
        if ( !classUri.startsWith("jar:") ) return null;
        int separatorIndex = classUri.lastIndexOf('!');
        if ( separatorIndex<=0 ) return null;
        String jarManifestUri = classUri.substring(0,separatorIndex+2);
        String containingWarManifestUri = jarManifestUri.substring(0,jarManifestUri.indexOf("WEB-INF")).replace("jar:file:/","file:///") + MANIFEST_FILE_PATH;
        URL url = new URL(containingWarManifestUri);
        inputStream = url.openStream();
        return inputStream;
    } catch ( Throwable e ) {
        // handle errors
        LOGGER.warn("No manifest file found in war file",e);
        return null;
    }
}
Related