org.springframework/spring-web/5.3.3 : org/springframework/web/method/ControllerAdviceBean.java

ControllerAdviceBean
https://github.com/spring-projects/spring-framework: Spring Web (Spring IO)
Apache License, Version 2.0
Juergen Hoeller
/*
 * Copyright 2002-2020 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.web.method;

import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

import org.springframework.aop.scope.ScopedProxyUtils;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.OrderComparator;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.AnnotatedElementUtils;
import org.springframework.core.annotation.OrderUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.web.bind.annotation.ControllerAdvice;

Encapsulates information about an @ControllerAdvice Spring-managed bean without necessarily requiring it to be instantiated. The findAnnotatedBeans(ApplicationContext) method can be used to discover such beans. However, a ControllerAdviceBean may be created from any object, including ones without an @ControllerAdvice annotation. 
Author: Rossen Stoyanchev, Brian Clozel, Juergen Hoeller, Sam Brannen
Since: 3.2/**
 * Encapsulates information about an {@link ControllerAdvice @ControllerAdvice}
 * Spring-managed bean without necessarily requiring it to be instantiated.
 *
 * <p>The {@link #findAnnotatedBeans(ApplicationContext)} method can be used to
 * discover such beans. However, a {@code ControllerAdviceBean} may be created
 * from any object, including ones without an {@code @ControllerAdvice} annotation.
 *
 * @author Rossen Stoyanchev
 * @author Brian Clozel
 * @author Juergen Hoeller
 * @author Sam Brannen
 * @since 3.2
 */
public class ControllerAdviceBean implements Ordered {

	Reference to the actual bean instance or a String representing the bean name. /**
	 * Reference to the actual bean instance or a {@code String} representing
	 * the bean name.
	 */
	private final Object beanOrName;

	private final boolean isSingleton;

	Reference to the resolved bean instance, potentially lazily retrieved via the BeanFactory. /**
	 * Reference to the resolved bean instance, potentially lazily retrieved
	 * via the {@code BeanFactory}.
	 */
	@Nullable
	private Object resolvedBean;

	@Nullable
	private final Class<?> beanType;

	private final HandlerTypePredicate beanTypePredicate;

	@Nullable
	private final BeanFactory beanFactory;

	@Nullable
	private Integer order;


	Create a ControllerAdviceBean using the given bean instance. 
Params: bean – the bean instance/**
	 * Create a {@code ControllerAdviceBean} using the given bean instance.
	 * @param bean the bean instance
	 */
	public ControllerAdviceBean(Object bean) {
		Assert.notNull(bean, "Bean must not be null");
		this.beanOrName = bean;
		this.isSingleton = true;
		this.resolvedBean = bean;
		this.beanType = ClassUtils.getUserClass(bean.getClass());
		this.beanTypePredicate = createBeanTypePredicate(this.beanType);
		this.beanFactory = null;
	}

	Create a ControllerAdviceBean using the given bean name and BeanFactory. 
Params: beanName – the name of the bean
beanFactory – a BeanFactory to retrieve the bean type initially and later to resolve the actual bean/**
	 * Create a {@code ControllerAdviceBean} using the given bean name and
	 * {@code BeanFactory}.
	 * @param beanName the name of the bean
	 * @param beanFactory a {@code BeanFactory} to retrieve the bean type initially
	 * and later to resolve the actual bean
	 */
	public ControllerAdviceBean(String beanName, BeanFactory beanFactory) {
		this(beanName, beanFactory, null);
	}

	Create a ControllerAdviceBean using the given bean name, BeanFactory, and @ControllerAdvice annotation. 
Params: beanName – the name of the bean
beanFactory – a BeanFactory to retrieve the bean type initially and later to resolve the actual bean
controllerAdvice – the @ControllerAdvice annotation for the bean, or null if not yet retrieved
Since: 5.2/**
	 * Create a {@code ControllerAdviceBean} using the given bean name,
	 * {@code BeanFactory}, and {@link ControllerAdvice @ControllerAdvice}
	 * annotation.
	 * @param beanName the name of the bean
	 * @param beanFactory a {@code BeanFactory} to retrieve the bean type initially
	 * and later to resolve the actual bean
	 * @param controllerAdvice the {@code @ControllerAdvice} annotation for the
	 * bean, or {@code null} if not yet retrieved
	 * @since 5.2
	 */
	public ControllerAdviceBean(String beanName, BeanFactory beanFactory, @Nullable ControllerAdvice controllerAdvice) {
		Assert.hasText(beanName, "Bean name must contain text");
		Assert.notNull(beanFactory, "BeanFactory must not be null");
		Assert.isTrue(beanFactory.containsBean(beanName), () -> "BeanFactory [" + beanFactory +
				"] does not contain specified controller advice bean '" + beanName + "'");

		this.beanOrName = beanName;
		this.isSingleton = beanFactory.isSingleton(beanName);
		this.beanType = getBeanType(beanName, beanFactory);
		this.beanTypePredicate = (controllerAdvice != null ? createBeanTypePredicate(controllerAdvice) :
				createBeanTypePredicate(this.beanType));
		this.beanFactory = beanFactory;
	}


	Get the order value for the contained bean.
As of Spring Framework 5.3, the order value is lazily retrieved using the following algorithm and cached. Note, however, that a @ControllerAdvice bean that is configured as a scoped bean — for example, as a request-scoped or session-scoped bean — will not be eagerly resolved. Consequently, Ordered is not honored for scoped @ControllerAdvice beans. 

If the resolved bean implements Ordered, use the value returned by Ordered.getOrder().
If the factory method is known, use the value returned by OrderUtils.getOrder(AnnotatedElement). 
If the bean type is known, use the value returned by OrderUtils.getOrder(Class<?>, int) with Ordered.LOWEST_PRECEDENCE used as the default order value.
Otherwise use Ordered.LOWEST_PRECEDENCE as the default, fallback order value.

See Also: resolveBean()/**
	 * Get the order value for the contained bean.
	 * <p>As of Spring Framework 5.3, the order value is lazily retrieved using
	 * the following algorithm and cached. Note, however, that a
	 * {@link ControllerAdvice @ControllerAdvice} bean that is configured as a
	 * scoped bean &mdash; for example, as a request-scoped or session-scoped
	 * bean &mdash; will not be eagerly resolved. Consequently, {@link Ordered} is
	 * not honored for scoped {@code @ControllerAdvice} beans.
	 * <ul>
	 * <li>If the {@linkplain #resolveBean resolved bean} implements {@link Ordered},
	 * use the value returned by {@link Ordered#getOrder()}.</li>
	 * <li>If the {@linkplain org.springframework.context.annotation.Bean factory method}
	 * is known, use the value returned by {@link OrderUtils#getOrder(AnnotatedElement)}.
	 * <li>If the {@linkplain #getBeanType() bean type} is known, use the value returned
	 * by {@link OrderUtils#getOrder(Class, int)} with {@link Ordered#LOWEST_PRECEDENCE}
	 * used as the default order value.</li>
	 * <li>Otherwise use {@link Ordered#LOWEST_PRECEDENCE} as the default, fallback
	 * order value.</li>
	 * </ul>
	 * @see #resolveBean()
	 */
	@Override
	public int getOrder() {
		if (this.order == null) {
			String beanName = null;
			Object resolvedBean = null;
			if (this.beanFactory != null && this.beanOrName instanceof String) {
				beanName = (String) this.beanOrName;
				String targetBeanName = ScopedProxyUtils.getTargetBeanName(beanName);
				boolean isScopedProxy = this.beanFactory.containsBean(targetBeanName);
				// Avoid eager @ControllerAdvice bean resolution for scoped proxies,
				// since attempting to do so during context initialization would result
				// in an exception due to the current absence of the scope. For example,
				// an HTTP request or session scope is not active during initialization.
				if (!isScopedProxy && !ScopedProxyUtils.isScopedTarget(beanName)) {
					resolvedBean = resolveBean();
				}
			}
			else {
				resolvedBean = resolveBean();
			}

			if (resolvedBean instanceof Ordered) {
				this.order = ((Ordered) resolvedBean).getOrder();
			}
			else {
				if (beanName != null && this.beanFactory instanceof ConfigurableBeanFactory) {
					ConfigurableBeanFactory cbf = (ConfigurableBeanFactory) this.beanFactory;
					try {
						BeanDefinition bd = cbf.getMergedBeanDefinition(beanName);
						if (bd instanceof RootBeanDefinition) {
							Method factoryMethod = ((RootBeanDefinition) bd).getResolvedFactoryMethod();
							if (factoryMethod != null) {
								this.order = OrderUtils.getOrder(factoryMethod);
							}
						}
					}
					catch (NoSuchBeanDefinitionException ex) {
						// ignore -> probably a manually registered singleton
					}
				}
				if (this.order == null) {
					if (this.beanType != null) {
						this.order = OrderUtils.getOrder(this.beanType, Ordered.LOWEST_PRECEDENCE);
					}
					else {
						this.order = Ordered.LOWEST_PRECEDENCE;
					}
				}
			}
		}
		return this.order;
	}

	Return the type of the contained bean.
If the bean type is a CGLIB-generated class, the original user-defined
class is returned.
/**
	 * Return the type of the contained bean.
	 * <p>If the bean type is a CGLIB-generated class, the original user-defined
	 * class is returned.
	 */
	@Nullable
	public Class<?> getBeanType() {
		return this.beanType;
	}

	Get the bean instance for this ControllerAdviceBean, if necessary resolving the bean name through the BeanFactory. As of Spring Framework 5.2, once the bean instance has been resolved it will be cached if it is a singleton, thereby avoiding repeated lookups in the BeanFactory. /**
	 * Get the bean instance for this {@code ControllerAdviceBean}, if necessary
	 * resolving the bean name through the {@link BeanFactory}.
	 * <p>As of Spring Framework 5.2, once the bean instance has been resolved it
	 * will be cached if it is a singleton, thereby avoiding repeated lookups in
	 * the {@code BeanFactory}.
	 */
	public Object resolveBean() {
		if (this.resolvedBean == null) {
			// this.beanOrName must be a String representing the bean name if
			// this.resolvedBean is null.
			Object resolvedBean = obtainBeanFactory().getBean((String) this.beanOrName);
			// Don't cache non-singletons (e.g., prototypes).
			if (!this.isSingleton) {
				return resolvedBean;
			}
			this.resolvedBean = resolvedBean;
		}
		return this.resolvedBean;
	}

	private BeanFactory obtainBeanFactory() {
		Assert.state(this.beanFactory != null, "No BeanFactory set");
		return this.beanFactory;
	}

	Check whether the given bean type should be advised by this ControllerAdviceBean. 
Params: beanType – the type of the bean to check
See Also: ControllerAdvice
Since: 4.0/**
	 * Check whether the given bean type should be advised by this
	 * {@code ControllerAdviceBean}.
	 * @param beanType the type of the bean to check
	 * @since 4.0
	 * @see ControllerAdvice
	 */
	public boolean isApplicableToBeanType(@Nullable Class<?> beanType) {
		return this.beanTypePredicate.test(beanType);
	}


	@Override
	public boolean equals(@Nullable Object other) {
		if (this == other) {
			return true;
		}
		if (!(other instanceof ControllerAdviceBean)) {
			return false;
		}
		ControllerAdviceBean otherAdvice = (ControllerAdviceBean) other;
		return (this.beanOrName.equals(otherAdvice.beanOrName) && this.beanFactory == otherAdvice.beanFactory);
	}

	@Override
	public int hashCode() {
		return this.beanOrName.hashCode();
	}

	@Override
	public String toString() {
		return this.beanOrName.toString();
	}


	Find beans annotated with @ControllerAdvice in the given ApplicationContext and wrap them as ControllerAdviceBean instances. As of Spring Framework 5.2, the ControllerAdviceBean instances in the returned list are sorted using OrderComparator.sort(List<?>). 
See Also: getOrder()
OrderComparator
Ordered/**
	 * Find beans annotated with {@link ControllerAdvice @ControllerAdvice} in the
	 * given {@link ApplicationContext} and wrap them as {@code ControllerAdviceBean}
	 * instances.
	 * <p>As of Spring Framework 5.2, the {@code ControllerAdviceBean} instances
	 * in the returned list are sorted using {@link OrderComparator#sort(List)}.
	 * @see #getOrder()
	 * @see OrderComparator
	 * @see Ordered
	 */
	public static List<ControllerAdviceBean> findAnnotatedBeans(ApplicationContext context) {
		ListableBeanFactory beanFactory = context;
		if (context instanceof ConfigurableApplicationContext) {
			// Use internal BeanFactory for potential downcast to ConfigurableBeanFactory above
			beanFactory = ((ConfigurableApplicationContext) context).getBeanFactory();
		}
		List<ControllerAdviceBean> adviceBeans = new ArrayList<>();
		for (String name : BeanFactoryUtils.beanNamesForTypeIncludingAncestors(beanFactory, Object.class)) {
			if (!ScopedProxyUtils.isScopedTarget(name)) {
				ControllerAdvice controllerAdvice = beanFactory.findAnnotationOnBean(name, ControllerAdvice.class);
				if (controllerAdvice != null) {
					// Use the @ControllerAdvice annotation found by findAnnotationOnBean()
					// in order to avoid a subsequent lookup of the same annotation.
					adviceBeans.add(new ControllerAdviceBean(name, beanFactory, controllerAdvice));
				}
			}
		}
		OrderComparator.sort(adviceBeans);
		return adviceBeans;
	}

	@Nullable
	private static Class<?> getBeanType(String beanName, BeanFactory beanFactory) {
		Class<?> beanType = beanFactory.getType(beanName);
		return (beanType != null ? ClassUtils.getUserClass(beanType) : null);
	}

	private static HandlerTypePredicate createBeanTypePredicate(@Nullable Class<?> beanType) {
		ControllerAdvice controllerAdvice = (beanType != null ?
				AnnotatedElementUtils.findMergedAnnotation(beanType, ControllerAdvice.class) : null);
		return createBeanTypePredicate(controllerAdvice);
	}

	private static HandlerTypePredicate createBeanTypePredicate(@Nullable ControllerAdvice controllerAdvice) {
		if (controllerAdvice != null) {
			return HandlerTypePredicate.builder()
					.basePackage(controllerAdvice.basePackages())
					.basePackageClass(controllerAdvice.basePackageClasses())
					.assignableType(controllerAdvice.assignableTypes())
					.annotation(controllerAdvice.annotations())
					.build();
		}
		return HandlerTypePredicate.forAnyHandlerType();
	}

}
Author:	Rossen Stoyanchev, Brian Clozel, Juergen Hoeller, Sam Brannen
Since:	3.2
Params:	beanName – the name of the bean beanFactory – a `BeanFactory` to retrieve the bean type initially and later to resolve the actual bean controllerAdvice – the `@ControllerAdvice` annotation for the bean, or `null` if not yet retrieved
Since:	5.2
Params:	beanType – the type of the bean to check
See Also:	ControllerAdvice
Since:	4.0
/

org.springframework/ spring-web/ 5.3.3/ org/springframework/web/method/ControllerAdviceBean.java
