org.eclipse.osgi.internal.serviceregistry.ServiceReferenceImpl Maven / Gradle / Ivy
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/*******************************************************************************
* Copyright (c) 2003, 2012 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.osgi.internal.serviceregistry;
import org.osgi.framework.*;
/**
* A reference to a service.
*
*
* The Framework returns ServiceReference objects from the
* BundleContext.getServiceReference and
* BundleContext.getServiceReferences methods.
*
* A ServiceReference object may be shared between bundles and
* can be used to examine the properties of the service and to get the service
* object.
*
* Every service registered in the Framework has a unique
* ServiceRegistration object and may have multiple, distinct
* ServiceReference objects referring to it.
* ServiceReference objects associated with a
* ServiceRegistration object have the same hashCode
* and are considered equal (more specifically, their equals()
* method will return true when compared).
*
* If the same service object is registered multiple times,
* ServiceReference objects associated with different
* ServiceRegistration objects are not equal.
*
* @see BundleContext#getServiceReference
* @see BundleContext#getServiceReferences
* @see BundleContext#getService
* @ThreadSafe
*/
public class ServiceReferenceImpl implements ServiceReference {
/** Registered Service object. */
private final ServiceRegistrationImpl registration;
/**
* Construct a reference.
*
*/
ServiceReferenceImpl(ServiceRegistrationImpl registration) {
this.registration = registration;
/* We must not dereference registration in the constructor
* since it is "leaked" to us in the ServiceRegistrationImpl
* constructor.
*/
}
/**
* Returns the property value to which the specified property key is mapped
* in the properties Dictionary object of the service
* referenced by this ServiceReference object.
*
*
* Property keys are case-insensitive.
*
*
* This method must continue to return property values after the service has
* been unregistered. This is so references to unregistered services (for
* example, ServiceReference objects stored in the log) can
* still be interrogated.
*
* @param key The property key.
* @return The property value to which the key is mapped; null
* if there is no property named after the key.
*/
public Object getProperty(String key) {
return registration.getProperty(key);
}
/**
* Returns an array of the keys in the properties Dictionary
* object of the service referenced by this ServiceReference
* object.
*
*
* This method will continue to return the keys after the service has been
* unregistered. This is so references to unregistered services (for
* example, ServiceReference objects stored in the log) can
* still be interrogated.
*
*
* This method is case-preserving ; this means that every key in the
* returned array must have the same case as the corresponding key in the
* properties Dictionary that was passed to the
* {@link BundleContext#registerService(String[],Object,java.util.Dictionary)}
* or {@link ServiceRegistration#setProperties} methods.
*
* @return An array of property keys.
*/
public String[] getPropertyKeys() {
return registration.getPropertyKeys();
}
/**
* Returns the bundle that registered the service referenced by this
* ServiceReference object.
*
*
* This method must return null when the service has been
* unregistered. This can be used to determine if the service has been
* unregistered.
*
* @return The bundle that registered the service referenced by this
* ServiceReference object; null if
* that service has already been unregistered.
* @see BundleContext#registerService(String[],Object,java.util.Dictionary)
*/
public Bundle getBundle() {
return registration.getBundle();
}
/**
* Returns the bundles that are using the service referenced by this
* ServiceReference object. Specifically, this method returns
* the bundles whose usage count for that service is greater than zero.
*
* @return An array of bundles whose usage count for the service referenced
* by this ServiceReference object is greater than
* zero; null if no bundles are currently using that
* service.
*
* @since 1.1
*/
public Bundle[] getUsingBundles() {
return registration.getUsingBundles();
}
/**
* Tests if the bundle that registered the service referenced by this
* ServiceReference and the specified bundle use the same
* source for the package of the specified class name.
*
* This method performs the following checks:
*
* - Get the package name from the specified class name.
* - For the bundle that registered the service referenced by this
*
ServiceReference (registrant bundle); find the source for
* the package. If no source is found then return true if the
* registrant bundle is equal to the specified bundle; otherwise return
* false.
* - If the package source of the registrant bundle is equal to the
* package source of the specified bundle then return
true;
* otherwise return false.
*
*
* @param bundle The Bundle object to check.
* @param className The class name to check.
* @return true if the bundle which registered the service
* referenced by this ServiceReference and the
* specified bundle use the same source for the package of the
* specified class name. Otherwise false is returned.
*
* @since 1.3
*/
public boolean isAssignableTo(Bundle bundle, String className) {
return registration.isAssignableTo(bundle, className);
}
/**
* Compares this ServiceReference with the specified
* ServiceReference for order.
*
*
* If this ServiceReference and the specified
* ServiceReference have the same
* {@link Constants#SERVICE_ID service id} they are equal. This
* ServiceReference is less than the specified
* ServiceReference if it has a lower
* {@link Constants#SERVICE_RANKING service ranking} and greater if it has a
* higher service ranking. Otherwise, if this ServiceReference
* and the specified ServiceReference have the same
* {@link Constants#SERVICE_RANKING service ranking}, this
* ServiceReference is less than the specified
* ServiceReference if it has a higher
* {@link Constants#SERVICE_ID service id} and greater if it has a lower
* service id.
*
* @param object The ServiceReference to be compared.
* @return Returns a negative integer, zero, or a positive integer if this
* ServiceReference is less than, equal to, or
* greater than the specified ServiceReference.
* @since 1.4
*/
public int compareTo(Object object) {
ServiceRegistrationImpl other = ((ServiceReferenceImpl) object).registration;
final int thisRanking = registration.getRanking();
final int otherRanking = other.getRanking();
if (thisRanking != otherRanking) {
if (thisRanking < otherRanking) {
return -1;
}
return 1;
}
final long thisId = registration.getId();
final long otherId = other.getId();
if (thisId == otherId) {
return 0;
}
if (thisId < otherId) {
return 1;
}
return -1;
}
/**
* Returns a hash code value for the object.
*
* @return a hash code value for this object.
*/
public int hashCode() {
return registration.hashCode();
}
/**
* Indicates whether some other object is "equal to" this one.
*
* @param obj the reference object with which to compare.
* @return true if this object is the same as the obj
* argument; false otherwise.
*/
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (!(obj instanceof ServiceReferenceImpl)) {
return false;
}
ServiceReferenceImpl other = (ServiceReferenceImpl) obj;
return registration == other.registration;
}
/**
* Return a string representation of this reference.
*
* @return String
*/
public String toString() {
return registration.toString();
}
/**
* Return the ServiceRegistrationImpl for this ServiceReferenceImpl.
*
* @return The ServiceRegistrationImpl for this ServiceReferenceImpl.
*/
public ServiceRegistrationImpl getRegistration() {
return registration;
}
/**
* Return the classes under which the referenced service was registered.
*
* @return array of class names.
*/
String[] getClasses() {
return registration.getClasses();
}
}