spring RepeatableContainers 源码

spring RepeatableContainers 代码

文件路径：/spring-core/src/main/java/org/springframework/core/annotation/RepeatableContainers.java

/*
 * Copyright 2002-2019 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
 *
 *      https://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.core.annotation;

import java.lang.annotation.Annotation;
import java.lang.annotation.Repeatable;
import java.lang.reflect.Method;
import java.util.Map;

import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ConcurrentReferenceHashMap;
import org.springframework.util.ObjectUtils;
import org.springframework.util.ReflectionUtils;

/**
 * Strategy used to determine annotations that act as containers for other
 * annotations. The {@link #standardRepeatables()} method provides a default
 * strategy that respects Java's {@link Repeatable @Repeatable} support and
 * should be suitable for most situations.
 *
 * <p>The {@link #of} method can be used to register relationships for
 * annotations that do not wish to use {@link Repeatable @Repeatable}.
 *
 * <p>To completely disable repeatable support use {@link #none()}.
 *
 * @author Phillip Webb
 * @since 5.2
 */
public abstract class RepeatableContainers {

	@Nullable
	private final RepeatableContainers parent;


	private RepeatableContainers(@Nullable RepeatableContainers parent) {
		this.parent = parent;
	}


	/**
	 * Add an additional explicit relationship between a contained and
	 * repeatable annotation.
	 * @param container the container type
	 * @param repeatable the contained repeatable type
	 * @return a new {@link RepeatableContainers} instance
	 */
	public RepeatableContainers and(Class<? extends Annotation> container,
			Class<? extends Annotation> repeatable) {

		return new ExplicitRepeatableContainer(this, repeatable, container);
	}

	@Nullable
	Annotation[] findRepeatedAnnotations(Annotation annotation) {
		if (this.parent == null) {
			return null;
		}
		return this.parent.findRepeatedAnnotations(annotation);
	}


	@Override
	public boolean equals(@Nullable Object other) {
		if (other == this) {
			return true;
		}
		if (other == null || getClass() != other.getClass()) {
			return false;
		}
		return ObjectUtils.nullSafeEquals(this.parent, ((RepeatableContainers) other).parent);
	}

	@Override
	public int hashCode() {
		return ObjectUtils.nullSafeHashCode(this.parent);
	}


	/**
	 * Create a {@link RepeatableContainers} instance that searches using Java's
	 * {@link Repeatable @Repeatable} annotation.
	 * @return a {@link RepeatableContainers} instance
	 */
	public static RepeatableContainers standardRepeatables() {
		return StandardRepeatableContainers.INSTANCE;
	}

	/**
	 * Create a {@link RepeatableContainers} instance that uses a defined
	 * container and repeatable type.
	 * @param repeatable the contained repeatable annotation
	 * @param container the container annotation or {@code null}. If specified,
	 * this annotation must declare a {@code value} attribute returning an array
	 * of repeatable annotations. If not specified, the container will be
	 * deduced by inspecting the {@code @Repeatable} annotation on
	 * {@code repeatable}.
	 * @return a {@link RepeatableContainers} instance
	 */
	public static RepeatableContainers of(
			Class<? extends Annotation> repeatable, @Nullable Class<? extends Annotation> container) {

		return new ExplicitRepeatableContainer(null, repeatable, container);
	}

	/**
	 * Create a {@link RepeatableContainers} instance that does not expand any
	 * repeatable annotations.
	 * @return a {@link RepeatableContainers} instance
	 */
	public static RepeatableContainers none() {
		return NoRepeatableContainers.INSTANCE;
	}


	/**
	 * Standard {@link RepeatableContainers} implementation that searches using
	 * Java's {@link Repeatable @Repeatable} annotation.
	 */
	private static class StandardRepeatableContainers extends RepeatableContainers {

		private static final Map<Class<? extends Annotation>, Object> cache = new ConcurrentReferenceHashMap<>();

		private static final Object NONE = new Object();

		private static StandardRepeatableContainers INSTANCE = new StandardRepeatableContainers();

		StandardRepeatableContainers() {
			super(null);
		}

		@Override
		@Nullable
		Annotation[] findRepeatedAnnotations(Annotation annotation) {
			Method method = getRepeatedAnnotationsMethod(annotation.annotationType());
			if (method != null) {
				return (Annotation[]) ReflectionUtils.invokeMethod(method, annotation);
			}
			return super.findRepeatedAnnotations(annotation);
		}

		@Nullable
		private static Method getRepeatedAnnotationsMethod(Class<? extends Annotation> annotationType) {
			Object result = cache.computeIfAbsent(annotationType,
					StandardRepeatableContainers::computeRepeatedAnnotationsMethod);
			return (result != NONE ? (Method) result : null);
		}

		private static Object computeRepeatedAnnotationsMethod(Class<? extends Annotation> annotationType) {
			AttributeMethods methods = AttributeMethods.forAnnotationType(annotationType);
			if (methods.hasOnlyValueAttribute()) {
				Method method = methods.get(0);
				Class<?> returnType = method.getReturnType();
				if (returnType.isArray()) {
					Class<?> componentType = returnType.getComponentType();
					if (Annotation.class.isAssignableFrom(componentType) &&
							componentType.isAnnotationPresent(Repeatable.class)) {
						return method;
					}
				}
			}
			return NONE;
		}
	}


	/**
	 * A single explicit mapping.
	 */
	private static class ExplicitRepeatableContainer extends RepeatableContainers {

		private final Class<? extends Annotation> repeatable;

		private final Class<? extends Annotation> container;

		private final Method valueMethod;

		ExplicitRepeatableContainer(@Nullable RepeatableContainers parent,
				Class<? extends Annotation> repeatable, @Nullable Class<? extends Annotation> container) {

			super(parent);
			Assert.notNull(repeatable, "Repeatable must not be null");
			if (container == null) {
				container = deduceContainer(repeatable);
			}
			Method valueMethod = AttributeMethods.forAnnotationType(container).get(MergedAnnotation.VALUE);
			try {
				if (valueMethod == null) {
					throw new NoSuchMethodException("No value method found");
				}
				Class<?> returnType = valueMethod.getReturnType();
				if (!returnType.isArray() || returnType.getComponentType() != repeatable) {
					throw new AnnotationConfigurationException("Container type [" +
							container.getName() +
							"] must declare a 'value' attribute for an array of type [" +
							repeatable.getName() + "]");
				}
			}
			catch (AnnotationConfigurationException ex) {
				throw ex;
			}
			catch (Throwable ex) {
				throw new AnnotationConfigurationException(
						"Invalid declaration of container type [" + container.getName() +
								"] for repeatable annotation [" + repeatable.getName() + "]",
						ex);
			}
			this.repeatable = repeatable;
			this.container = container;
			this.valueMethod = valueMethod;
		}

		private Class<? extends Annotation> deduceContainer(Class<? extends Annotation> repeatable) {
			Repeatable annotation = repeatable.getAnnotation(Repeatable.class);
			Assert.notNull(annotation, () -> "Annotation type must be a repeatable annotation: " +
						"failed to resolve container type for " + repeatable.getName());
			return annotation.value();
		}

		@Override
		@Nullable
		Annotation[] findRepeatedAnnotations(Annotation annotation) {
			if (this.container.isAssignableFrom(annotation.annotationType())) {
				return (Annotation[]) ReflectionUtils.invokeMethod(this.valueMethod, annotation);
			}
			return super.findRepeatedAnnotations(annotation);
		}

		@Override
		public boolean equals(@Nullable Object other) {
			if (!super.equals(other)) {
				return false;
			}
			ExplicitRepeatableContainer otherErc = (ExplicitRepeatableContainer) other;
			return (this.container.equals(otherErc.container) && this.repeatable.equals(otherErc.repeatable));
		}

		@Override
		public int hashCode() {
			int hashCode = super.hashCode();
			hashCode = 31 * hashCode + this.container.hashCode();
			hashCode = 31 * hashCode + this.repeatable.hashCode();
			return hashCode;
		}
	}


	/**
	 * No repeatable containers.
	 */
	private static class NoRepeatableContainers extends RepeatableContainers {

		private static NoRepeatableContainers INSTANCE = new NoRepeatableContainers();

		NoRepeatableContainers() {
			super(null);
		}
	}

}

相关信息

spring 源码目录

相关文章

spring AbstractMergedAnnotation 源码

spring AliasFor 源码

spring AnnotatedElementUtils 源码

spring AnnotationAttributes 源码

spring AnnotationAwareOrderComparator 源码

spring AnnotationConfigurationException 源码

spring AnnotationFilter 源码

spring AnnotationTypeMapping 源码

spring AnnotationTypeMappings 源码

spring AnnotationUtils 源码