I'm investigating OSGI-ifying a large codebase, and am trying to pin down how we're going to do resource loading. At the bottom of this message is a bit of code that's called many times in the codebase. It can take anything from a filename to a URL string to a resource path, and turn it into a canonical URL that can be passed to anything in the Java libraries that take a URL.
Questions: 1. I think ClassLoader.getSystemResource(spec) is going to get me into trouble in OSGi-land. I'm not sure the Thread.currentThread().getContextClassLoader().getResource(spec); is any better. However, this is what was recommended by Sun in http://java.sun.com/j2se/1.5.0/docs/guide/javaws/developersguide/faq.htm l#211 when trying to make our code work in JNLP-land. Would AnyInputStream.class.getResource(spec) work any better? 2. Felix sees the string "C:\dir\file" as a URL with protocol "C:" (and throws malformed URL exception since it doesn't recognize that protocol) when it tries to to look it up as a resource. Moving the attempt to stat the File to before the resource calls solves that problem, but the common case is that we store the file in a resource, so we're doing a lot of extra file stats if I make that change. 3. I'd like to avoid OSGI-specific code in the core codebase and rely on the classpath-mangling magic to accomplish this... but do I need to move away from static calls to do it? Would a singleton pattern work better here, or are singletons, too, evil in a multi-classloader world? --Sam Kass class AnyInputStream { //... public static URL makeURL(String spec) throws IllegalArgumentException { // For applets/webstart, we should use this thread's ClassLoader, which // will default to the system classloader if it hasn't been overridden URL url = Thread.currentThread().getContextClassLoader().getResource(spec); // Call back to the SystemResouce if we can't find it if (null == url) url = ClassLoader.getSystemResource(spec); // Try parsing it as a pre-formed URL if (null == url) { try { url = new URL(spec); } catch (MalformedURLException e) { url = null; } } // If we couldn't find it from the classloader, try the local filesystem if (url == null) { try { File file = new File(spec); if (file.isFile()) { url = file.toURL(); } } catch (MalformedURLException e) { //throw new IllegalArgumentException("Unable to open: " + onedoc); } } if (url == null) { throw new IllegalArgumentException( "Unable to create URL from \"" + spec + "\""); } return url; } }
