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How to get BundleContext of a plugin? [message #906022]

Fri, 31 August 2012 09:28

Eclipse User

Hi,

Can someone tell me how to get BundleContext of a plugin?

I used,
BundleContext bc=FrameworkUtil.getBundle(new com.kosala.model.src.Activator().getClass()).getBundleContext();

This gives:
Exception in thread "main" java.lang.NullPointerException.

Thanks
K

Re: How to get BundleContext of a plugin? [message #906031 is a reply to message #906022]

Fri, 31 August 2012 09:42

Eclipse User

Why do you want the bundle context?

The bundle context is the context that your bundle runs under, this is something that should NEVER be passed outside of the bundle that owns it. Rarely will I ever even pass it out of the activator. But to get it from the activator, it looks like this:

public class Activator implements BundleActivator {

	static private Activator defaultInstance;
	private BundleContext bundleContext;

	// List any services here
	// private ServiceTracker myService;

	public Activator() {
		defaultInstance = this;
	}

	public static Activator getDefault() {
		return defaultInstance;
	}

	public void start(BundleContext context) throws Exception {
		bundleContext = context;
	}

	public void stop(BundleContext context) throws Exception {
		// Stop your services here
		// if (myService != null) {
		//	myService.close();
		//	myService = null;
		// }

		bundleContext = null;
	}

	// Notice that this method is -> ONLY <- available within the package
	BundleContext getBundleContext() {
		return bundleContext;
	}

	// Retrieve and start your service here, something like:
	// public MyService getMyService() {
	// 	if (myService == null) {
	// 		if (bundleContext == null)
	// 			return null;
	//		myService = new ServiceTracker(bundleContext, MyService.class.getName(), null);
	//		myService.open();
	//	}
	//	return (MyService) myService.getService();
	// }

}

[Updated on: Fri, 31 August 2012 09:42] by Moderator

Re: How to get BundleContext of a plugin? [message #906044 is a reply to message #906031]

Fri, 31 August 2012 10:08

Eclipse User

JD is absolutely correct.

For more information, read the javadoc on org.osgi.framework.BundleContext. It explains how the context is made available to the activator and is only valid while the bundle it is associated with is executing. It is possible to adapt a Bundle to its BundleContext, but it is likely that code from another bundle will be denied.

Re: How to get BundleContext of a plugin? [message #906062 is a reply to message #906044]

Fri, 31 August 2012 10:42

Eclipse User

Thanks for your replies.

My main problem is,

http://www.eclipse.org/forums/index.php/t/371441/

I always get null for bundle.

I just want to access a resource file in another plugin, using that plugin name.

Kosala

Re: How to get BundleContext of a plugin? [message #930676 is a reply to message #906031]

Tue, 02 October 2012 10:29

Eclipse User

Joseph, I've been searching for a simple way to get a reference to the bundle context. Your solution is very straightforward, and it definitely worked.

I used your example to revise my Activator class. Then in a different (servlet) class in the same package, I obtained a reference to the BundleContext object using these two lines:

    Activator activatorRef = Activator.getDefault();
    BundleContext bc = activatorRef.getBundleContext();

And then was able to get a framework property as a test:

    String fwOSVersion = bc.getProperty(Constants.FRAMEWORK_OS_VERSION);

Thank you!
David

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