001/*
002 * Copyright 2002-2019 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.bind.annotation;
018
019import java.lang.annotation.Annotation;
020import java.lang.annotation.Documented;
021import java.lang.annotation.ElementType;
022import java.lang.annotation.Retention;
023import java.lang.annotation.RetentionPolicy;
024import java.lang.annotation.Target;
025
026import org.springframework.core.annotation.AliasFor;
027import org.springframework.stereotype.Component;
028
029/**
030 * Specialization of {@link Component @Component} for classes that declare
031 * {@link ExceptionHandler @ExceptionHandler}, {@link InitBinder @InitBinder}, or
032 * {@link ModelAttribute @ModelAttribute} methods to be shared across
033 * multiple {@code @Controller} classes.
034 *
035 * <p>Classes annotated with {@code @ControllerAdvice} can be declared explicitly
036 * as Spring beans or auto-detected via classpath scanning. All such beans are
037 * sorted based on {@link org.springframework.core.Ordered Ordered} semantics or
038 * {@link org.springframework.core.annotation.Order @Order} /
039 * {@link javax.annotation.Priority @Priority} declarations, with {@code Ordered}
040 * semantics taking precedence over {@code @Order} / {@code @Priority} declarations.
041 * {@code @ControllerAdvice} beans are then applied in that order at runtime.
042 * Note, however, that {@code @ControllerAdvice} beans that implement
043 * {@link org.springframework.core.PriorityOrdered PriorityOrdered} are <em>not</em>
044 * given priority over {@code @ControllerAdvice} beans that implement {@code Ordered}.
045 * In addition, {@code Ordered} is not honored for scoped {@code @ControllerAdvice}
046 * beans &mdash; for example if such a bean has been configured as a request-scoped
047 * or session-scoped bean.  For handling exceptions, an {@code @ExceptionHandler}
048 * will be picked on the first advice with a matching exception handler method. For
049 * model attributes and data binding initialization, {@code @ModelAttribute} and
050 * {@code @InitBinder} methods will follow {@code @ControllerAdvice} order.
051 *
052 * <p>Note: For {@code @ExceptionHandler} methods, a root exception match will be
053 * preferred to just matching a cause of the current exception, among the handler
054 * methods of a particular advice bean. However, a cause match on a higher-priority
055 * advice will still be preferred over any match (whether root or cause level)
056 * on a lower-priority advice bean. As a consequence, please declare your primary
057 * root exception mappings on a prioritized advice bean with a corresponding order.
058 *
059 * <p>By default, the methods in an {@code @ControllerAdvice} apply globally to
060 * all controllers. Use selectors such as {@link #annotations},
061 * {@link #basePackageClasses}, and {@link #basePackages} (or its alias
062 * {@link #value}) to define a more narrow subset of targeted controllers.
063 * If multiple selectors are declared, boolean {@code OR} logic is applied, meaning
064 * selected controllers should match at least one selector. Note that selector checks
065 * are performed at runtime, so adding many selectors may negatively impact
066 * performance and add complexity.
067 *
068 * @author Rossen Stoyanchev
069 * @author Brian Clozel
070 * @author Sam Brannen
071 * @since 3.2
072 * @see org.springframework.stereotype.Controller
073 * @see RestControllerAdvice
074 */
075@Target(ElementType.TYPE)
076@Retention(RetentionPolicy.RUNTIME)
077@Documented
078@Component
079public @interface ControllerAdvice {
080
081        /**
082         * Alias for the {@link #basePackages} attribute.
083         * <p>Allows for more concise annotation declarations &mdash; for example,
084         * {@code @ControllerAdvice("org.my.pkg")} is equivalent to
085         * {@code @ControllerAdvice(basePackages = "org.my.pkg")}.
086         * @since 4.0
087         * @see #basePackages
088         */
089        @AliasFor("basePackages")
090        String[] value() default {};
091
092        /**
093         * Array of base packages.
094         * <p>Controllers that belong to those base packages or sub-packages thereof
095         * will be included &mdash; for example,
096         * {@code @ControllerAdvice(basePackages = "org.my.pkg")} or
097         * {@code @ControllerAdvice(basePackages = {"org.my.pkg", "org.my.other.pkg"})}.
098         * <p>{@link #value} is an alias for this attribute, simply allowing for
099         * more concise use of the annotation.
100         * <p>Also consider using {@link #basePackageClasses} as a type-safe
101         * alternative to String-based package names.
102         * @since 4.0
103         */
104        @AliasFor("value")
105        String[] basePackages() default {};
106
107        /**
108         * Type-safe alternative to {@link #basePackages} for specifying the packages
109         * in which to select controllers to be advised by the {@code @ControllerAdvice}
110         * annotated class.
111         * <p>Consider creating a special no-op marker class or interface in each package
112         * that serves no purpose other than being referenced by this attribute.
113         * @since 4.0
114         */
115        Class<?>[] basePackageClasses() default {};
116
117        /**
118         * Array of classes.
119         * <p>Controllers that are assignable to at least one of the given types
120         * will be advised by the {@code @ControllerAdvice} annotated class.
121         * @since 4.0
122         */
123        Class<?>[] assignableTypes() default {};
124
125        /**
126         * Array of annotation types.
127         * <p>Controllers that are annotated with at least one of the supplied annotation
128         * types will be advised by the {@code @ControllerAdvice} annotated class.
129         * <p>Consider creating a custom composed annotation or use a predefined one,
130         * like {@link RestController @RestController}.
131         * @since 4.0
132         */
133        Class<? extends Annotation>[] annotations() default {};
134
135}