OsgiBundleUtils.java :  » J2EE » spring-ide_2.3.0 » org » springframework » osgi » util » Java Open Source

/*
 * 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 org.springframework.osgi.util;

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

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;

/**
 * Utility class for OSGi {@link 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 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 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 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 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 (int i = 0; i < bundles.length; i++) {
      if (symbolicName.equals(bundles[i].getSymbolicName())) {
        return bundles[i];
      }
    }
    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((String) bundle.getHeaders().get(header));
  }
}