spring.osgi.utils.OsgiBundleUtils.java Source code

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Here is the source code for spring.osgi.utils.OsgiBundleUtils.java

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/*
 * Copyright 2006-2008 the original author or authors.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package spring.osgi.utils;

import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.Version;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ReflectionUtils.FieldCallback;
import org.springframework.util.ReflectionUtils.FieldFilter;

import java.lang.reflect.Field;
import java.lang.reflect.Method;

/**
 * Utility class for OSGi {@link org.osgi.framework.Bundle}s. Provides convenience methods for
 * interacting with a Bundle object.
 *
 * @author Adrian Colyer
 * @author Costin Leau
 * @see OsgiStringUtils
 */
public abstract class OsgiBundleUtils {

    /**
     * Returns the underlying BundleContext for the given Bundle. This uses
     * reflection and highly dependent of the OSGi implementation. Should not be
     * used if OSGi 4.1 is being used.
     *
     * @param bundle OSGi bundle
     * @return the bundle context for this bundle
     */
    public static BundleContext getBundleContext(final Bundle bundle) {
        if (bundle == null)
            return null;

        // try Equinox getContext
        Method meth = ReflectionUtils.findMethod(bundle.getClass(), "getContext", new Class[0]);

        // fallback to getBundleContext (OSGi 4.1)
        if (meth == null)
            meth = ReflectionUtils.findMethod(bundle.getClass(), "getBundleContext", new Class[0]);

        final Method m = meth;

        if (meth != null) {
            ReflectionUtils.makeAccessible(meth);
            return (BundleContext) ReflectionUtils.invokeMethod(m, bundle);
        }

        // fallback to field inspection (KF and Prosyst)
        final BundleContext[] ctx = new BundleContext[1];

        ReflectionUtils.doWithFields(bundle.getClass(), new FieldCallback() {

            public void doWith(final Field field) throws IllegalArgumentException, IllegalAccessException {
                ReflectionUtils.makeAccessible(field);
                ctx[0] = (BundleContext) field.get(bundle);
            }
        }, new FieldFilter() {

            public boolean matches(Field field) {
                return BundleContext.class.isAssignableFrom(field.getType());
            }
        });

        return ctx[0];
    }

    /**
     * Indicates if the given bundle is active or not.
     *
     * @param bundle OSGi bundle
     * @return true if the given bundle is active, false otherwise
     * @see org.osgi.framework.Bundle#ACTIVE
     */
    public static boolean isBundleActive(Bundle bundle) {
        Assert.notNull(bundle, "bundle is required");
        return (bundle.getState() == Bundle.ACTIVE);
    }

    /**
     * Indicates if the given bundle is resolved or not.
     *
     * @param bundle OSGi bundle
     * @return true if the given bundle is resolved, false otherwise
     * @see org.osgi.framework.Bundle#RESOLVED
     */
    public static boolean isBundleResolved(Bundle bundle) {
        Assert.notNull(bundle, "bundle is required");
        return (bundle.getState() >= Bundle.RESOLVED);
    }

    /**
     * Indicates if the given bundle is a fragment or not.
     *
     * @param bundle OSGi bundle
     * @return true if the given bundle is a fragment, false otherwise
     * @see org.osgi.framework.Constants#FRAGMENT_HOST
     */
    public static boolean isFragment(Bundle bundle) {
        Assert.notNull(bundle, "bundle is required");
        return bundle.getHeaders().get(Constants.FRAGMENT_HOST) != null;
    }

    /**
     * Indicates if the given bundle is the system bundle or not.
     *
     * @param bundle OSGi bundle
     * @return true if the given bundle is a fragment, false otherwise
     */
    public static boolean isSystemBundle(Bundle bundle) {
        Assert.notNull(bundle);
        return (bundle.getBundleId() == 0);
    }

    /**
     * Returns the given bundle version.
     *
     * @param bundle OSGi bundle
     * @return bundle version
     * @see org.osgi.framework.Constants#BUNDLE_VERSION
     */
    public static Version getBundleVersion(Bundle bundle) {
        return getHeaderAsVersion(bundle, Constants.BUNDLE_VERSION);
    }

    /**
     * Finds an install bundle based by its symbolic name.
     *
     * @param bundleContext OSGi bundle context
     * @param symbolicName  bundle symbolic name
     * @return bundle matching the symbolic name (<code>null</code> if none
     * is found)
     */
    public static Bundle findBundleBySymbolicName(BundleContext bundleContext, String symbolicName) {
        Assert.notNull(bundleContext, "bundleContext is required");
        Assert.hasText(symbolicName, "a not-null/not-empty symbolicName isrequired");

        Bundle[] bundles = bundleContext.getBundles();
        for (Bundle bundle : bundles) {
            if (symbolicName.equals(bundle.getSymbolicName())) {
                return bundle;
            }
        }
        return null;
    }

    /**
     * Returns the version for a given bundle manifest header.
     *
     * @param bundle OSGi bundle
     * @param header bundle manifest header
     * @return the header value
     */
    public static Version getHeaderAsVersion(Bundle bundle, String header) {
        Assert.notNull(bundle);
        return Version.parseVersion(bundle.getHeaders().get(header));
    }
}