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.annotation.Order @Order}
038 * semantics and applied in that order at runtime. For handling exceptions, an
039 * {@code @ExceptionHandler} will be picked on the first advice with a matching
040 * exception handler method. For model attributes and {@code InitBinder}
041 * initialization, {@code @ModelAttribute} and {@code @InitBinder} methods will
042 * also follow {@code @ControllerAdvice} order.
043 *
044 * <p>Note: For {@code @ExceptionHandler} methods, a root exception match will be
045 * preferred to just matching a cause of the current exception, among the handler
046 * methods of a particular advice bean. However, a cause match on a higher-priority
047 * advice will still be preferred over any match (whether root or cause level)
048 * on a lower-priority advice bean. As a consequence, please declare your primary
049 * root exception mappings on a prioritized advice bean with a corresponding order.
050 *
051 * <p>By default the methods in an {@code @ControllerAdvice} apply globally to
052 * all controllers. Use selectors such as {@link #annotations},
053 * {@link #basePackageClasses}, and {@link #basePackages} (or its alias
054 * {@link #value}) to define a more narrow subset of targeted controllers.
055 * If multiple selectors are declared, {@code OR} logic is applied, meaning selected
056 * controllers should match at least one selector. Note that selector checks
057 * are performed at runtime, so adding many selectors may negatively impact
058 * performance and add complexity.
059 *
060 * @author Rossen Stoyanchev
061 * @author Brian Clozel
062 * @author Sam Brannen
063 * @since 3.2
064 */
065@Target(ElementType.TYPE)
066@Retention(RetentionPolicy.RUNTIME)
067@Documented
068@Component
069public @interface ControllerAdvice {
070
071        /**
072         * Alias for the {@link #basePackages} attribute.
073         * <p>Allows for more concise annotation declarations e.g.:
074         * {@code @ControllerAdvice("org.my.pkg")} is equivalent to
075         * {@code @ControllerAdvice(basePackages="org.my.pkg")}.
076         * @since 4.0
077         * @see #basePackages()
078         */
079        @AliasFor("basePackages")
080        String[] value() default {};
081
082        /**
083         * Array of base packages.
084         * <p>Controllers that belong to those base packages or sub-packages thereof
085         * will be included, e.g.: {@code @ControllerAdvice(basePackages="org.my.pkg")}
086         * or {@code @ControllerAdvice(basePackages={"org.my.pkg", "org.my.other.pkg"})}.
087         * <p>{@link #value} is an alias for this attribute, simply allowing for
088         * more concise use of the annotation.
089         * <p>Also consider using {@link #basePackageClasses()} as a type-safe
090         * alternative to String-based package names.
091         * @since 4.0
092         */
093        @AliasFor("value")
094        String[] basePackages() default {};
095
096        /**
097         * Type-safe alternative to {@link #value()} for specifying the packages
098         * to select Controllers to be assisted by the {@code @ControllerAdvice}
099         * annotated class.
100         * <p>Consider creating a special no-op marker class or interface in each package
101         * that serves no purpose other than being referenced by this attribute.
102         * @since 4.0
103         */
104        Class<?>[] basePackageClasses() default {};
105
106        /**
107         * Array of classes.
108         * <p>Controllers that are assignable to at least one of the given types
109         * will be assisted by the {@code @ControllerAdvice} annotated class.
110         * @since 4.0
111         */
112        Class<?>[] assignableTypes() default {};
113
114        /**
115         * Array of annotations.
116         * <p>Controllers that are annotated with this/one of those annotation(s)
117         * will be assisted by the {@code @ControllerAdvice} annotated class.
118         * <p>Consider creating a special annotation or use a predefined one,
119         * like {@link RestController @RestController}.
120         * @since 4.0
121         */
122        Class<? extends Annotation>[] annotations() default {};
123
124}