org.openide.util.lookup.ServiceProvider Maven / Gradle / Ivy
/*
* 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.openide.util.lookup;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.openide.util.Lookup;
/**
* Declarative registration of a singleton service provider.
* By marking an implementation class with this annotation,
* you automatically register that implementation, normally in {@link Lookup#getDefault}.
* The class must be public and have a public no-argument constructor.
* Example of usage:
*
* package my.module;
* import org.netbeans.spi.whatever.Thing;
* import org.openide.util.lookup.ServiceProvider;
* @ServiceProvider(service=Thing.class)
* public class MyThing implements Thing {...}
*
* would result in a resource file META-INF/services/org.netbeans.spi.whatever.Thing
* containing the single line of text: my.module.MyThing
* @see Lookups#metaInfServices(ClassLoader)
* @since org.openide.util 7.20
*/
@Retention(RetentionPolicy.SOURCE)
@Target(ElementType.TYPE)
public @interface ServiceProvider {
/**
* The interface (or abstract class) to register this implementation under.
* It is an error if the implementation class is not in fact assignable to the interface.
*
If you need to register one class under multiple interfaces, use {@link ServiceProviders}.
*
Requests to look up the specified interface should result in this implementation.
* Requests for any other types may or may not result in this implementation even if the
* implementation is assignable to those types.
*/
Class service();
/**
* An optional position in which to register this service relative to others.
* Lower-numbered services are returned in the lookup result first.
* Services with no specified position are returned last.
*/
int position() default Integer.MAX_VALUE;
/**
* An optional list of implementations (given as fully-qualified class names) which this implementation supersedes.
* If specified, those implementations will not be loaded even if they were registered.
* Useful on occasion to cancel a generic implementation and replace it with a more advanced one.
*
*
Note: Dollar sign ($) is used in inner class names. For example
* org.netbeans.modules.openfile.FileChooser$JavaFilesFilter.
*/
String[] supersedes() default {};
/**
* An optional path to register this implementation in.
* For example, Projects/sometype/Nodes could be used.
* This style of registration would be recognized by {@link Lookups#forPath}
* rather than {@link Lookup#getDefault}.
*
* The providers of a registration slot are advised to have
* a look at {@link NamedServiceDefinition} and consider using it since
* version 8.14.
* The {@link NamedServiceDefinition} offers various benefits over
* plain {@link #path()} usage including type checking and lower
* possibility of typos.
*/
String path() default "";
}