On 12/28/10 6:14 PM, Bjorn Roche wrote:
3. The next step was to go through bit-by-bit and fix all the
dynamic class loading and resource loading. Since I've actually
not found good documentation explaining, from a user's standpoint,
how to do this, I just centralized my code and found something
that gets it done. If I'm doing it wrong, at least it's
centralized so I can change it easily.
- if a bundle is available (OSGi case) use the classloader from
the bundle.
- if there is an object that likely used the same classloader I
wanted, which is often the case, get that object's classloader.
- failing that, eg, if I'm in a static context -- I use something
like this:
Thread.currentThread().getContextClassLoader().loadClass(path);
Not sure about all this. I have to assume you are doing some
low-level stuff, since bundles typically shouldn't be doing this
sort of thing.
I'm not doing anything special or low-level that I'm aware of. I did
that stuff because I discovered that
Thread.currentThread().getContextClassLoader().getResource() doesn't
work in OSGi, nor does the System Classloader, but using the bundle
did work.
What /should/ I be doing to dynamically load classes and resources?
Typically, bundles shouldn't have to dynamically load classes
manually, so it sounds like an advanced use case so far. If you are
integrating legacy third-party stuff, then you might not have a
choice, but if it is your own stuff it can quite possibly be avoided
through the use of services. Hard to say.
Okay. Theoretically, I could get rid of all the dynamic class loading,
as it turns out to have been a bit overdesigned anyway, but leaving
that asside, what about resources? If I just want a png or jpg from
the classpath? That is pretty standard. For example, I load several
thousand images from a resource directory, using code not unlike the
code in the java tutorial
(http://download.oracle.com/javase/tutorial/uiswing/components/icon.html):
/** Returns an ImageIcon, or null if the path was invalid. */
protected ImageIcon createImageIcon(String path,
String description) {
java.net.URL imgURL = getClass().getResource(path);
if (imgURL != null) {
return new ImageIcon(imgURL, description);
} else {
System.err.println("Couldn't find file: " + path);
return null;
}
}
"Low level" or not, can you clarify about the right way to do this? Is
there a better way to do this than using the bundle?
Well, resources can be put into packages and shared like classes via
exports...or am I missing something?
-> richard
bjorn
-----------------------------
Bjorn Roche
http://www.xonami.com
Audio Collaboration
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