/*
* Copyright 2002-2016 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.cache.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.util.concurrent.Callable;
import org.springframework.core.annotation.AliasFor;
/**
* Annotation indicating that the result of invoking a method (or all methods
* in a class) can be cached.
*
* <p>Each time an advised method is invoked, caching behavior will be applied,
* checking whether the method has been already invoked for the given arguments.
* A sensible default simply uses the method parameters to compute the key, but
* a SpEL expression can be provided via the {@link #key} attribute, or a custom
* {@link org.springframework.cache.interceptor.KeyGenerator} implementation can
* replace the default one (see {@link #keyGenerator}).
*
* <p>If no value is found in the cache for the computed key, the target method
* will be invoked and the returned value stored in the associated cache. Note
* that Java8's {@code Optional} return types are automatically handled and its
* content is stored in the cache if present.
*
* <p>This annotation may be used as a <em>meta-annotation</em> to create custom
* <em>composed annotations</em> with attribute overrides.
*
* @author Costin Leau
* @author Phillip Webb
* @author Stephane Nicoll
* @author Sam Brannen
* @since 3.1
* @see CacheConfig
*/
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface Cacheable {
/**
* Alias for {@link #cacheNames}.
*/
@AliasFor("cacheNames")
String[] value() default {};
/**
* Names of the caches in which method invocation results are stored.
* <p>Names may be used to determine the target cache (or caches), matching
* the qualifier value or bean name of a specific bean definition.
* @since 4.2
* @see #value
* @see CacheConfig#cacheNames
*/
@AliasFor("value")
String[] cacheNames() default {};
/**
* Spring Expression Language (SpEL) expression for computing the key dynamically.
* <p>Default is {@code ""}, meaning all method parameters are considered as a key,
* unless a custom {@link #keyGenerator} has been configured.
* <p>The SpEL expression evaluates against a dedicated context that provides the
* following meta-data:
* <ul>
* <li>{@code #root.method}, {@code #root.target}, and {@code #root.caches} for
* references to the {@link java.lang.reflect.Method method}, target object, and
* affected cache(s) respectively.</li>
* <li>Shortcuts for the method name ({@code #root.methodName}) and target class
* ({@code #root.targetClass}) are also available.
* <li>Method arguments can be accessed by index. For instance the second argument
* can be accessed via {@code #root.args[1]}, {@code #p1} or {@code #a1}. Arguments
* can also be accessed by name if that information is available.</li>
* </ul>
*/
String key() default "";
/**
* The bean name of the custom {@link org.springframework.cache.interceptor.KeyGenerator}
* to use.
* <p>Mutually exclusive with the {@link #key} attribute.
* @see CacheConfig#keyGenerator
*/
String keyGenerator() default "";
/**
* The bean name of the custom {@link org.springframework.cache.CacheManager} to use to
* create a default {@link org.springframework.cache.interceptor.CacheResolver} if none
* is set already.
* <p>Mutually exclusive with the {@link #cacheResolver} attribute.
* @see org.springframework.cache.interceptor.SimpleCacheResolver
* @see CacheConfig#cacheManager
*/
String cacheManager() default "";
/**
* The bean name of the custom {@link org.springframework.cache.interceptor.CacheResolver}
* to use.
* @see CacheConfig#cacheResolver
*/
String cacheResolver() default "";
/**
* Spring Expression Language (SpEL) expression used for making the method
* caching conditional.
* <p>Default is {@code ""}, meaning the method result is always cached.
* <p>The SpEL expression evaluates against a dedicated context that provides the
* following meta-data:
* <ul>
* <li>{@code #root.method}, {@code #root.target}, and {@code #root.caches} for
* references to the {@link java.lang.reflect.Method method}, target object, and
* affected cache(s) respectively.</li>
* <li>Shortcuts for the method name ({@code #root.methodName}) and target class
* ({@code #root.targetClass}) are also available.
* <li>Method arguments can be accessed by index. For instance the second argument
* can be accessed via {@code #root.args[1]}, {@code #p1} or {@code #a1}. Arguments
* can also be accessed by name if that information is available.</li>
* </ul>
*/
String condition() default "";
/**
* Spring Expression Language (SpEL) expression used to veto method caching.
* <p>Unlike {@link #condition}, this expression is evaluated after the method
* has been called and can therefore refer to the {@code result}.
* <p>Default is {@code ""}, meaning that caching is never vetoed.
* <p>The SpEL expression evaluates against a dedicated context that provides the
* following meta-data:
* <ul>
* <li>{@code #result} for a reference to the result of the method invocation. For
* supported wrappers such as {@code Optional}, {@code #result} refers to the actual
* object, not the wrapper</li>
* <li>{@code #root.method}, {@code #root.target}, and {@code #root.caches} for
* references to the {@link java.lang.reflect.Method method}, target object, and
* affected cache(s) respectively.</li>
* <li>Shortcuts for the method name ({@code #root.methodName}) and target class
* ({@code #root.targetClass}) are also available.
* <li>Method arguments can be accessed by index. For instance the second argument
* can be accessed via {@code #root.args[1]}, {@code #p1} or {@code #a1}. Arguments
* can also be accessed by name if that information is available.</li>
* </ul>
* @since 3.2
*/
String unless() default "";
/**
* Synchronize the invocation of the underlying method if several threads are
* attempting to load a value for the same key. The synchronization leads to
* a couple of limitations:
* <ol>
* <li>{@link #unless()} is not supported</li>
* <li>Only one cache may be specified</li>
* <li>No other cache-related operation can be combined</li>
* </ol>
* This is effectively a hint and the actual cache provider that you are
* using may not support it in a synchronized fashion. Check your provider
* documentation for more details on the actual semantics.
* @since 4.3
* @see org.springframework.cache.Cache#get(Object, Callable)
*/
boolean sync() default false;
}