org.apache.felix.scr.annotations.Reference Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.felix.scr.annotations;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* The Reference annotation defines references to other services
* made available to the component by the Service Component Runtime.
*
* This annotation may be declared for a Java Class or any Java Field to which
* it might apply. Depending on where the annotation is declared, the parameters
* may have different default values.
*
* This annotation is used to declare <reference> elements of the
* component declaration. See section 112.4.7, Reference Element, in the OSGi
* Service Platform Service Compendium Specification for more information.
*/
@Target( { ElementType.TYPE, ElementType.FIELD })
@Retention(RetentionPolicy.CLASS)
@Documented
public @interface Reference {
/**
* The local name of the reference. If the annotation is declared on class
* level, this parameter is required. If the tag is declared for a field,
* the default value for the name parameter is the name of the field.
*/
String name() default "";
/**
* The name of the service interface. This name is used by the Service
* Component Runtime to access the service on behalf of the component. If
* the annotation is declared on class level, this parameter is required. If
* the annotation is declared for a field, the default value for the
* interface parameter is the type of the field.
*/
Class referenceInterface() default AutoDetect.class;
/**
* The cardinality of the service reference. This must be one of 0..1, 1..1,
* 0..n, and 1..n.
*/
ReferenceCardinality cardinality() default ReferenceCardinality.MANDATORY_UNARY;
/**
* The dynamicity policy of the reference. If dynamic the service will be
* made available to the component as it comes and goes. If static the
* component will be deactivated and re-activated if the service comes
* and/or goes away.
*/
ReferencePolicy policy() default ReferencePolicy.STATIC;
/**
* The policy option for the reference
* @since 1.7
*/
ReferencePolicyOption policyOption() default ReferencePolicyOption.RELUCTANT;
/**
* A service target filter to select specific services to be made available.
* In order to be able to overwrite the value of this value by a
* configuration property, this parameter must be declared. If the parameter
* is not declared, the respective declaration attribute will not be
* generated.
*/
String target() default "";
/**
* The name of the method to be called when the service is to be bound to
* the component. The default value is the name created by appending the
* reference name to the string bind. The method must be declared
* public or protected and take single argument
* which is declared with the service interface type.
*/
String bind() default "";
/**
* The name of the method to be called when the service is to be unbound
* from the component. The default value is the name created by appending
* the reference name to the string unbind. The method must be declared
* public or protected and take single argument
* which is declared with the service interface type.
*/
String unbind() default "";
/**
* The name of the method to be called when the bound service updates its
* service registration properties. By default this is not set.
*/
String updated() default "";
/**
* The reference strategy for the reference. This can either be
* {@link ReferenceStrategy#EVENT} in which case the bind and unbind
* methods are used or it can be {@link ReferenceStrategy#LOOKUP}
* in which case the reference is looked up through the
* component context.
*/
ReferenceStrategy strategy() default ReferenceStrategy.EVENT;
}