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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.dubbo.common.extension;
import org.apache.dubbo.common.URL;
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;
/**
* Activate. This annotation is useful for automatically activate certain extensions with the given criteria,
* for examples: @Activate
can be used to load certain Filter
extension when there are
* multiple implementations.
*
* - {@link Activate#group()} specifies group criteria. Framework SPI defines the valid group values.
*
- {@link Activate#value()} specifies parameter key in {@link URL} criteria.
*
* SPI provider can call {@link ExtensionLoader#getActivateExtension(URL, String, String)} to find out all activated
* extensions with the given criteria.
*
* @see SPI
* @see URL
* @see ExtensionLoader
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
public @interface Activate {
/**
* Activate the current extension when one of the groups matches. The group passed into
* {@link ExtensionLoader#getActivateExtension(URL, String, String)} will be used for matching.
*
* @return group names to match
* @see ExtensionLoader#getActivateExtension(URL, String, String)
*/
String[] group() default {};
/**
* Activate the current extension when the specified keys appear in the URL's parameters.
*
* For example, given @Activate("cache, validation")
, the current extension will be return only when
* there's either cache
or validation
key appeared in the URL's parameters.
*
*
* @return URL parameter keys
* @see ExtensionLoader#getActivateExtension(URL, String)
* @see ExtensionLoader#getActivateExtension(URL, String, String)
*/
String[] value() default {};
/**
* Relative ordering info, optional
* Deprecated since 2.7.0
*
* @return extension list which should be put before the current one
*/
@Deprecated
String[] before() default {};
/**
* Relative ordering info, optional
* Deprecated since 2.7.0
*
* @return extension list which should be put after the current one
*/
@Deprecated
String[] after() default {};
/**
* Absolute ordering info, optional
*
* Ascending order, smaller values will be in the front o the list.
*
* @return absolute ordering info
*/
int order() default 0;
}