Moving toward bundles - OSGi in Action - page 223

jEdit

JARClassLoader

PluginJAR

jEdit

JARClassLoader PluginJAR

Common plugin API

OSGi mapping layer

Figure 6.10 Extracting a
common jEdit plugin API

How about being able to register OSG i bundles as jEdit plugins? This is a stepping
stone to using services, because you need a bundle context to access OSG i services.
The main jEdit class provides two static methods to add and remove plugin JAR files:

public static void addPluginJAR(String path);

public static void removePluginJAR(PluginJAR jar, boolean exit);
Following the extender pattern introduced in section 3.4, let's use a bundle tracker to
look for potential jEdit plugins. The code in the following listing uses a tracker to add
and remove jEdit plugin bundles as they come and go.

Listing 6.4 Using the extender pattern to install jEdit plugins

package org.foo.jedit.extender;

import java.io.File;
import org.gjt.sp.jedit.*;
import org.osgi.framework.*;

public class Activator implements BundleActivator {

BundleTracker pluginTracker;

public void start(final BundleContext ctx) {
pluginTracker = new BundleTracker(ctx) {

actions.xml B

Looks for

public void addedBundle(Bundle bundle) {
String path = getBundlePath(bundle);
if (path != null && bundle.getResource("actions.xml") != null) {
jEdit.addPluginJAR(path);
}
}