cn.taketoday.core.annotation.MergedAnnotations Maven / Gradle / Ivy
/*
* Original Author -> Harry Yang ([email protected]) https://taketoday.cn
* Copyright © TODAY & 2017 - 2021 All Rights Reserved.
*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see [http://www.gnu.org/licenses/]
*/
package cn.taketoday.core.annotation;
import java.lang.annotation.Annotation;
import java.lang.annotation.Inherited;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.function.Predicate;
import java.util.stream.Stream;
import cn.taketoday.lang.Assert;
import cn.taketoday.lang.Nullable;
/**
* Provides access to a collection of merged annotations, usually obtained
* from a source such as a {@link Class} or {@link Method}.
*
* Each merged annotation represents a view where the attribute values may be
* "merged" from different source values, typically:
*
*
* - Explicit and Implicit {@link AliasFor @AliasFor} declarations on one or
* more attributes within the annotation
* - Explicit {@link AliasFor @AliasFor} declarations for a meta-annotation
* - Convention based attribute aliases for a meta-annotation
* - From a meta-annotation declaration
*
*
* For example, a {@code @PostMapping} annotation might be defined as follows:
*
*
* @Retention(RetentionPolicy.RUNTIME)
* @RequestMapping(method = HttpMethod.POST)
* public @interface PostMapping {
*
* @AliasFor(attribute = "path")
* String[] value() default {};
*
* @AliasFor(attribute = "value")
* String[] path() default {};
* }
*
*
* If a method is annotated with {@code @PostMapping("/home")} it will contain
* merged annotations for both {@code @PostMapping} and the meta-annotation
* {@code @RequestMapping}. The merged view of the {@code @RequestMapping}
* annotation will contain the following attributes:
*
*
*
* Name
* Value
* Source
*
*
* value
* "/home"
* Declared in {@code @PostMapping}
*
*
* path
* "/home"
* Explicit {@code @AliasFor}
*
*
* method
* HttpMethod.POST
* Declared in meta-annotation
*
*
*
* {@link MergedAnnotations} can be obtained {@linkplain #from(AnnotatedElement)
* from} any Java {@link AnnotatedElement}. They may also be used for sources that
* don't use reflection (such as those that directly parse bytecode).
*
*
Different {@linkplain SearchStrategy search strategies} can be used to locate
* related source elements that contain the annotations to be aggregated. For
* example, the following code uses {@link SearchStrategy#TYPE_HIERARCHY} to
* search for annotations on {@code MyClass} as well as in superclasses and implemented
* interfaces.
*
*
* MergedAnnotations mergedAnnotations =
* MergedAnnotations.search(TYPE_HIERARCHY).from(MyClass.class);
*
*
* From a {@link MergedAnnotations} instance you can either
* {@linkplain #get(String) get} a single annotation, or {@linkplain #stream()
* stream all annotations} or just those that match {@linkplain #stream(String)
* a specific type}. You can also quickly tell if an annotation
* {@linkplain #isPresent(String) is present}.
*
*
Here are some typical examples:
*
*
* // is an annotation present or meta-present?
* mergedAnnotations.isPresent(ExampleAnnotation.class);
*
* // get the merged "value" attribute of ExampleAnnotation (either directly or
* // meta-present)
* mergedAnnotations.get(ExampleAnnotation.class).getString("value");
*
* // get all meta-annotations but no directly present annotations
* mergedAnnotations.stream().filter(MergedAnnotation::isMetaPresent);
*
* // get all ExampleAnnotation declarations (including any meta-annotations) and
* // print the merged "value" attributes
* mergedAnnotations.stream(ExampleAnnotation.class)
* .map(mergedAnnotation -> mergedAnnotation.getString("value"))
* .forEach(System.out::println);
*
*
* NOTE: The {@code MergedAnnotations} API and its underlying model have
* been designed for composable annotations in common component model,
* with a focus on attribute aliasing and meta-annotation relationships.
* There is no support for retrieving plain Java annotations with this API;
* please use standard Java reflection or {@link AnnotationUtils}
* for simple annotation retrieval purposes.
*
* @author Phillip Webb
* @author Sam Brannen
* @see MergedAnnotation
* @see MergedAnnotationCollectors
* @see MergedAnnotationPredicates
* @see MergedAnnotationSelectors
* @since 4.0
*/
public interface MergedAnnotations extends Iterable> {
/**
* Determine if the specified annotation is either directly present or
* meta-present.
* Equivalent to calling {@code get(annotationType).isPresent()}.
*
* @param annotationType the annotation type to check
* @return {@code true} if the annotation is present
*/
boolean isPresent(Class annotationType);
/**
* Determine if the specified annotation is either directly present or
* meta-present.
* Equivalent to calling {@code get(annotationType).isPresent()}.
*
* @param annotationType the fully qualified class name of the annotation type
* to check
* @return {@code true} if the annotation is present
*/
boolean isPresent(String annotationType);
/**
* Determine if the specified annotation is directly present.
*
Equivalent to calling {@code get(annotationType).isDirectlyPresent()}.
*
* @param annotationType the annotation type to check
* @return {@code true} if the annotation is directly present
*/
boolean isDirectlyPresent(Class annotationType);
/**
* Determine if the specified annotation is directly present.
* Equivalent to calling {@code get(annotationType).isDirectlyPresent()}.
*
* @param annotationType the fully qualified class name of the annotation type
* to check
* @return {@code true} if the annotation is directly present
*/
boolean isDirectlyPresent(String annotationType);
/**
* Get the {@linkplain MergedAnnotationSelectors#nearest() nearest} matching
* annotation or meta-annotation of the specified type, or
* {@link MergedAnnotation#missing()} if none is present.
*
* @param annotationType the annotation type to get
* @return a {@link MergedAnnotation} instance
*/
MergedAnnotation get(Class annotationType);
/**
* Get the {@linkplain MergedAnnotationSelectors#nearest() nearest} matching
* annotation or meta-annotation of the specified type, or
* {@link MergedAnnotation#missing()} if none is present.
*
* @param annotationType the annotation type to get
* @param predicate a predicate that must match, or {@code null} if only
* type matching is required
* @return a {@link MergedAnnotation} instance
* @see MergedAnnotationPredicates
*/
MergedAnnotation get(
Class annotationType, @Nullable Predicate> predicate);
/**
* Get a matching annotation or meta-annotation of the specified type, or
* {@link MergedAnnotation#missing()} if none is present.
*
* @param annotationType the annotation type to get
* @param predicate a predicate that must match, or {@code null} if only
* type matching is required
* @param selector a selector used to choose the most appropriate annotation
* within an aggregate, or {@code null} to select the
* {@linkplain MergedAnnotationSelectors#nearest() nearest}
* @return a {@link MergedAnnotation} instance
* @see MergedAnnotationPredicates
* @see MergedAnnotationSelectors
*/
MergedAnnotation get(
Class annotationType,
@Nullable Predicate> predicate,
@Nullable MergedAnnotationSelector selector);
/**
* Get the {@linkplain MergedAnnotationSelectors#nearest() nearest} matching
* annotation or meta-annotation of the specified type, or
* {@link MergedAnnotation#missing()} if none is present.
*
* @param annotationType the fully qualified class name of the annotation type
* to get
* @return a {@link MergedAnnotation} instance
*/
MergedAnnotation get(String annotationType);
/**
* Get the {@linkplain MergedAnnotationSelectors#nearest() nearest} matching
* annotation or meta-annotation of the specified type, or
* {@link MergedAnnotation#missing()} if none is present.
*
* @param annotationType the fully qualified class name of the annotation type
* to get
* @param predicate a predicate that must match, or {@code null} if only
* type matching is required
* @return a {@link MergedAnnotation} instance
* @see MergedAnnotationPredicates
*/
MergedAnnotation get(
String annotationType, @Nullable Predicate> predicate);
/**
* Get a matching annotation or meta-annotation of the specified type, or
* {@link MergedAnnotation#missing()} if none is present.
*
* @param annotationType the fully qualified class name of the annotation type
* to get
* @param predicate a predicate that must match, or {@code null} if only
* type matching is required
* @param selector a selector used to choose the most appropriate annotation
* within an aggregate, or {@code null} to select the
* {@linkplain MergedAnnotationSelectors#nearest() nearest}
* @return a {@link MergedAnnotation} instance
* @see MergedAnnotationPredicates
* @see MergedAnnotationSelectors
*/
MergedAnnotation get(
String annotationType,
@Nullable Predicate> predicate,
@Nullable MergedAnnotationSelector selector);
/**
* Stream all annotations and meta-annotations that match the specified
* type. The resulting stream follows the same ordering rules as
* {@link #stream()}.
*
* @param annotationType the annotation type to match
* @return a stream of matching annotations
*/
Stream> stream(Class annotationType);
/**
* Stream all annotations and meta-annotations that match the specified
* type. The resulting stream follows the same ordering rules as
* {@link #stream()}.
*
* @param annotationType the fully qualified class name of the annotation type
* to match
* @return a stream of matching annotations
*/
Stream> stream(String annotationType);
/**
* Stream all annotations and meta-annotations contained in this collection.
* The resulting stream is ordered first by the
* {@linkplain MergedAnnotation#getAggregateIndex() aggregate index} and then
* by the annotation distance (with the closest annotations first). This ordering
* means that, for most use-cases, the most suitable annotations appear
* earliest in the stream.
*
* @return a stream of annotations
*/
Stream> stream();
AnnotationAttributes[] getAttributes(Class annotationType);
/**
* Create a new {@link MergedAnnotations} instance containing all
* annotations and meta-annotations from the specified element. The
* resulting instance will not include any inherited annotations. If you
* want to include those as well you should use
* {@link #from(AnnotatedElement, SearchStrategy)} with an appropriate
* {@link SearchStrategy}.
*
* @param element the source element
* @return a {@link MergedAnnotations} instance containing the element's
* annotations
* @see #search(SearchStrategy)
*/
static MergedAnnotations from(AnnotatedElement element) {
return from(element, SearchStrategy.DIRECT);
}
/**
* Create a new {@link MergedAnnotations} instance containing all
* annotations and meta-annotations from the specified element and,
* depending on the {@link SearchStrategy}, related inherited elements.
*
* @param element the source element
* @param searchStrategy the search strategy to use
* @return a {@link MergedAnnotations} instance containing the merged
* element annotations
* @see #search(SearchStrategy)
*/
static MergedAnnotations from(AnnotatedElement element, SearchStrategy searchStrategy) {
return from(element, searchStrategy, RepeatableContainers.standard());
}
/**
* Create a new {@link MergedAnnotations} instance containing all
* annotations and meta-annotations from the specified element and,
* depending on the {@link SearchStrategy}, related inherited elements.
*
* @param element the source element
* @param searchStrategy the search strategy to use
* @param repeatableContainers the repeatable containers that may be used by
* the element annotations or the meta-annotations
* @return a {@link MergedAnnotations} instance containing the merged
* element annotations
* @see #search(SearchStrategy)
*/
static MergedAnnotations from(
AnnotatedElement element, SearchStrategy searchStrategy, RepeatableContainers repeatableContainers) {
return from(element, searchStrategy, repeatableContainers, AnnotationFilter.PLAIN);
}
/**
* Create a new {@link MergedAnnotations} instance containing all
* annotations and meta-annotations from the specified element and,
* depending on the {@link SearchStrategy}, related inherited elements.
*
* @param element the source element
* @param searchStrategy the search strategy to use
* @param repeatableContainers the repeatable containers that may be used by
* the element annotations or the meta-annotations
* @param annotationFilter an annotation filter used to restrict the
* annotations considered
* @return a {@link MergedAnnotations} instance containing the merged
* annotations for the supplied element
* @see #search(SearchStrategy)
*/
static MergedAnnotations from(
AnnotatedElement element, SearchStrategy searchStrategy,
RepeatableContainers repeatableContainers, AnnotationFilter annotationFilter) {
Assert.notNull(element, "AnnotatedElement must not be null");
Assert.notNull(searchStrategy, "SearchStrategy must not be null");
Assert.notNull(repeatableContainers, "RepeatableContainers must not be null");
Assert.notNull(annotationFilter, "AnnotationFilter must not be null");
return TypeMappedAnnotations.from(element, searchStrategy, repeatableContainers, annotationFilter);
}
/**
* Create a new {@link MergedAnnotations} instance from the specified
* annotations.
*
* @param annotations the annotations to include
* @return a {@link MergedAnnotations} instance containing the annotations
* @see #from(Object, Annotation...)
* @see #search(SearchStrategy)
*/
static MergedAnnotations from(Annotation... annotations) {
return from(annotations, annotations);
}
/**
* Create a new {@link MergedAnnotations} instance from the specified
* annotations.
*
* @param source the source for the annotations. This source is used only
* for information and logging. It does not need to actually
* contain the specified annotations, and it will not be searched.
* @param annotations the annotations to include
* @return a {@link MergedAnnotations} instance containing the annotations
* @see #from(Annotation...)
* @see #from(AnnotatedElement)
* @see #search(SearchStrategy)
*/
static MergedAnnotations from(Object source, Annotation... annotations) {
return from(source, annotations, RepeatableContainers.standard());
}
/**
* Create a new {@link MergedAnnotations} instance from the specified
* annotations.
*
* @param source the source for the annotations. This source is used only
* for information and logging. It does not need to actually
* contain the specified annotations, and it will not be searched.
* @param annotations the annotations to include
* @param repeatableContainers the repeatable containers that may be used by
* meta-annotations
* @return a {@link MergedAnnotations} instance containing the annotations
* @see #search(SearchStrategy)
*/
static MergedAnnotations from(Object source, Annotation[] annotations, RepeatableContainers repeatableContainers) {
return from(source, annotations, repeatableContainers, AnnotationFilter.PLAIN);
}
/**
* Create a new {@link MergedAnnotations} instance from the specified
* annotations.
*
* @param source the source for the annotations. This source is used only
* for information and logging. It does not need to actually
* contain the specified annotations, and it will not be searched.
* @param annotations the annotations to include
* @param repeatableContainers the repeatable containers that may be used by
* meta-annotations
* @param annotationFilter an annotation filter used to restrict the
* annotations considered
* @return a {@link MergedAnnotations} instance containing the annotations
* @see #search(SearchStrategy)
*/
static MergedAnnotations from(
Object source, Annotation[] annotations,
RepeatableContainers repeatableContainers, AnnotationFilter annotationFilter) {
Assert.notNull(repeatableContainers, "RepeatableContainers must not be null");
Assert.notNull(annotationFilter, "AnnotationFilter must not be null");
return TypeMappedAnnotations.from(source, annotations, repeatableContainers, annotationFilter);
}
/**
* Create a new {@link MergedAnnotations} instance from the specified
* collection of directly present annotations. This method allows a
* {@link MergedAnnotations} instance to be created from annotations that
* are not necessarily loaded using reflection. The provided annotations
* must all be {@link MergedAnnotation#isDirectlyPresent() directly present}
* and must have an {@link MergedAnnotation#getAggregateIndex() aggregate
* index} of {@code 0}.
* The resulting {@link MergedAnnotations} instance will contain both the
* specified annotations, and any meta-annotations that can be read using
* reflection.
*
* @param annotations the annotations to include
* @return a {@link MergedAnnotations} instance containing the annotations
* @see MergedAnnotation#valueOf(ClassLoader, Object, Class, java.util.Map)
* @see TypeMappedAnnotations#NONE
*/
static MergedAnnotations valueOf(@Nullable Collection> annotations) {
return MergedAnnotationsCollection.valueOf(annotations);
}
/**
* Find merged annotations using the supplied {@link SearchStrategy} and a
* fluent API for configuring and performing the search.
* See {@link Search} for details.
*
* @param searchStrategy the search strategy to use
* @return a {@code Search} instance to perform the search
*/
static Search search(SearchStrategy searchStrategy) {
Assert.notNull(searchStrategy, "SearchStrategy must not be null");
return new Search(searchStrategy);
}
/**
* Fluent API for configuring the search algorithm used in the
* {@link MergedAnnotations} model and performing a search.
*
*
* - Configuration starts with an invocation of
* {@link MergedAnnotations#search(SearchStrategy)}, specifying which
* {@link SearchStrategy} to use.
* - Optional configuration can be provided via one of the {@code with*()}
* methods.
* - The actual search is performed by invoking {@link #from(AnnotatedElement)}
* with the source element from which the search should begin.
*
*
* For example, the following performs a search on {@code MyClass} within
* the entire type hierarchy of that class while ignoring repeatable annotations.
*
*
* MergedAnnotations mergedAnnotations =
* MergedAnnotations.search(SearchStrategy.TYPE_HIERARCHY)
* .withRepeatableContainers(RepeatableContainers.none())
* .from(MyClass.class);
*
*
* If you wish to reuse search configuration to perform the same type of search
* on multiple elements, you can save the {@code Search} instance as demonstrated
* in the following example.
*
*
* Search search = MergedAnnotations.search(SearchStrategy.TYPE_HIERARCHY)
* .withRepeatableContainers(RepeatableContainers.none());
*
* MergedAnnotations mergedAnnotations = search.from(MyClass.class);
* // do something with the MergedAnnotations for MyClass
* mergedAnnotations = search.from(AnotherClass.class);
* // do something with the MergedAnnotations for AnotherClass
*
*/
static final class Search {
private final SearchStrategy searchStrategy;
private RepeatableContainers repeatableContainers = RepeatableContainers.standard();
private AnnotationFilter annotationFilter = AnnotationFilter.PLAIN;
private Search(SearchStrategy searchStrategy) {
this.searchStrategy = searchStrategy;
}
/**
* Configure the {@link RepeatableContainers} to use.
* Defaults to {@link RepeatableContainers#standard()}.
*
* @param repeatableContainers the repeatable containers that may be used
* by annotations or meta-annotations
* @return this {@code Search} instance for chained method invocations
* @see #withAnnotationFilter(AnnotationFilter)
* @see #from(AnnotatedElement)
*/
public Search withRepeatableContainers(RepeatableContainers repeatableContainers) {
Assert.notNull(repeatableContainers, "RepeatableContainers must not be null");
this.repeatableContainers = repeatableContainers;
return this;
}
/**
* Configure the {@link AnnotationFilter} to use.
*
Defaults to {@link AnnotationFilter#PLAIN}.
*
* @param annotationFilter an annotation filter used to restrict the
* annotations considered
* @return this {@code Search} instance for chained method invocations
* @see #withRepeatableContainers(RepeatableContainers)
* @see #from(AnnotatedElement)
*/
public Search withAnnotationFilter(AnnotationFilter annotationFilter) {
Assert.notNull(annotationFilter, "AnnotationFilter must not be null");
this.annotationFilter = annotationFilter;
return this;
}
/**
* Perform a search for merged annotations beginning with the supplied
* {@link AnnotatedElement} (such as a {@link Class} or {@link Method}),
* using the configuration in this {@code Search} instance.
*
* @param element the source element
* @return a new {@link MergedAnnotations} instance containing all
* annotations and meta-annotations from the specified element and,
* depending on the {@link SearchStrategy}, related inherited elements
* @see #withRepeatableContainers(RepeatableContainers)
* @see #withAnnotationFilter(AnnotationFilter)
* @see MergedAnnotations#from(AnnotatedElement, SearchStrategy, RepeatableContainers, AnnotationFilter)
*/
public MergedAnnotations from(AnnotatedElement element) {
return MergedAnnotations.from(element, searchStrategy, repeatableContainers, annotationFilter);
}
}
/**
* Search strategies supported by {@link MergedAnnotations#search(SearchStrategy)}
* as well as {@link MergedAnnotations#from(AnnotatedElement, SearchStrategy)}
* and variants of that method.
*
*
Each strategy creates a different set of aggregates that will be
* combined to create the final {@link MergedAnnotations}.
*/
enum SearchStrategy {
/**
* Find only directly declared annotations, without considering
* {@link Inherited @Inherited} annotations and without searching
* superclasses or implemented interfaces.
*/
DIRECT,
/**
* Find all directly declared annotations as well as any
* {@link Inherited @Inherited} superclass annotations. This strategy
* is only really useful when used with {@link Class} types since the
* {@link Inherited @Inherited} annotation is ignored for all other
* {@linkplain AnnotatedElement annotated elements}. This strategy does
* not search implemented interfaces.
*/
INHERITED_ANNOTATIONS,
/**
* Find all directly declared and superclass annotations. This strategy
* is similar to {@link #INHERITED_ANNOTATIONS} except the annotations
* do not need to be meta-annotated with {@link Inherited @Inherited}.
* This strategy does not search implemented interfaces.
*/
SUPERCLASS,
/**
* Perform a full search of the entire type hierarchy, including
* superclasses and implemented interfaces. Superclass annotations do
* not need to be meta-annotated with {@link Inherited @Inherited}.
*/
TYPE_HIERARCHY,
/**
* Perform a full search of the entire type hierarchy on the source
* and any enclosing classes. This strategy is similar to
* {@link #TYPE_HIERARCHY} except that {@linkplain Class#getEnclosingClass()
* enclosing classes} are also searched. Superclass annotations do not
* need to be meta-annotated with {@link Inherited @Inherited}. When
* searching a {@link Method} source, this strategy is identical to
* {@link #TYPE_HIERARCHY}.
*/
TYPE_HIERARCHY_AND_ENCLOSING_CLASSES
}
}