How do I read the manifest file for a webapp running in apache tomcat?

Posted by Nik Reiman on Stack Overflow See other posts from Stack Overflow or by Nik Reiman
Published on 2009-03-05T16:19:15Z Indexed on 2010/03/18 11:31 UTC
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I have a webapp which contains a manifest file, in which I write the current version of my application during an ant build task. The manifest file is created correctly, but when I try to read it in during runtime, I get some strange side-effects. My code for reading in the manifest is something like this:

    InputStream manifestStream = Thread.currentThread()
                                 .getContextClassLoader()
                                 .getResourceAsStream("META-INFFFF/MANIFEST.MF");
    try {
    	Manifest manifest = new Manifest(manifestStream);
    	Attributes attributes = manifest.getMainAttributes();
    	String impVersion = attributes.getValue("Implementation-Version");
    	mVersionString = impVersion;
    }
    catch(IOException ex) {
    	logger.warn("Error while reading version: " + ex.getMessage());
    }

When I attach eclipse to tomcat, I see that the above code works, but it seems to get a different manifest file than the one I expected, which I can tell because the ant version and build timestamp are both different. Then, I put "META-INFFFF" in there, and the above code still works! This means that I'm reading some other manifest, not mine. I also tried

this.getClass().getClassLoader().getResourceAsStream(...)

But the result was the same. What's the proper way to read the manifest file from inside of a webapp running in tomcat?

Edit: Thanks for the suggestions so far. Also, I should note that I am running tomcat standalone; I launch it from the command line, and then attach to the running instance in Eclipse's debugger. That shouldn't make a difference, should it?

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