org.springframework.context.annotation.ComponentScan Maven / Gradle / Ivy
/*
* Copyright 2002-2023 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.context.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.beans.factory.support.BeanNameGenerator;
import org.springframework.core.annotation.AliasFor;
import org.springframework.core.type.filter.TypeFilter;
/**
* Configures component scanning directives for use with {@link Configuration @Configuration}
* classes.
*
* Provides support comparable to Spring's {@code }
* XML namespace element.
*
* Either {@link #basePackageClasses} or {@link #basePackages} (or its alias
* {@link #value}) may be specified to define specific packages to scan. If specific
* packages are not defined, scanning will occur recursively beginning with the
* package of the class that declares this annotation.
*
*
Note that the {@code } element has an
* {@code annotation-config} attribute; however, this annotation does not. This is because
* in almost all cases when using {@code @ComponentScan}, default annotation config
* processing (for example, processing {@code @Autowired} and friends) is assumed. Furthermore,
* when using {@link AnnotationConfigApplicationContext}, annotation config processors are
* always registered, meaning that any attempt to disable them at the
* {@code @ComponentScan} level would be ignored.
*
* See {@link Configuration @Configuration}'s Javadoc for usage examples.
*
*
{@code @ComponentScan} can be used as a {@linkplain Repeatable repeatable}
* annotation. {@code @ComponentScan} may also be used as a meta-annotation
* to create custom composed annotations with attribute overrides.
*
*
Locally declared {@code @ComponentScan} annotations always take precedence
* over and effectively hide {@code @ComponentScan} meta-annotations,
* which allows explicit local configuration to override configuration that is
* meta-present (including composed annotations meta-annotated with
* {@code @ComponentScan}).
*
* @author Chris Beams
* @author Juergen Hoeller
* @author Sam Brannen
* @since 3.1
* @see Configuration
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Repeatable(ComponentScans.class)
public @interface ComponentScan {
/**
* Alias for {@link #basePackages}.
*
Allows for more concise annotation declarations if no other attributes
* are needed — for example, {@code @ComponentScan("org.my.pkg")}
* instead of {@code @ComponentScan(basePackages = "org.my.pkg")}.
*/
@AliasFor("basePackages")
String[] value() default {};
/**
* Base packages to scan for annotated components.
*
{@link #value} is an alias for (and mutually exclusive with) this
* attribute.
*
Use {@link #basePackageClasses} for a type-safe alternative to
* String-based package names.
*/
@AliasFor("value")
String[] basePackages() default {};
/**
* Type-safe alternative to {@link #basePackages} for specifying the packages
* to scan for annotated components. The package of each class specified will be scanned.
*
Consider creating a special no-op marker class or interface in each package
* that serves no purpose other than being referenced by this attribute.
*/
Class[] basePackageClasses() default {};
/**
* The {@link BeanNameGenerator} class to be used for naming detected components
* within the Spring container.
*
The default value of the {@link BeanNameGenerator} interface itself indicates
* that the scanner used to process this {@code @ComponentScan} annotation should
* use its inherited bean name generator, for example, the default
* {@link AnnotationBeanNameGenerator} or any custom instance supplied to the
* application context at bootstrap time.
* @see AnnotationConfigApplicationContext#setBeanNameGenerator(BeanNameGenerator)
* @see AnnotationBeanNameGenerator
* @see FullyQualifiedAnnotationBeanNameGenerator
*/
Class nameGenerator() default BeanNameGenerator.class;
/**
* The {@link ScopeMetadataResolver} to be used for resolving the scope of detected components.
*/
Class scopeResolver() default AnnotationScopeMetadataResolver.class;
/**
* Indicates whether proxies should be generated for detected components, which may be
* necessary when using scopes in a proxy-style fashion.
*
The default is defer to the default behavior of the component scanner used to
* execute the actual scan.
*
Note that setting this attribute overrides any value set for {@link #scopeResolver}.
* @see ClassPathBeanDefinitionScanner#setScopedProxyMode(ScopedProxyMode)
*/
ScopedProxyMode scopedProxy() default ScopedProxyMode.DEFAULT;
/**
* Controls the class files eligible for component detection.
*
Consider use of {@link #includeFilters} and {@link #excludeFilters}
* for a more flexible approach.
*/
String resourcePattern() default ClassPathScanningCandidateComponentProvider.DEFAULT_RESOURCE_PATTERN;
/**
* Indicates whether automatic detection of classes annotated with {@code @Component}
* {@code @Repository}, {@code @Service}, or {@code @Controller} should be enabled.
*/
boolean useDefaultFilters() default true;
/**
* Specifies which types are eligible for component scanning.
*
Further narrows the set of candidate components from everything in {@link #basePackages}
* to everything in the base packages that matches the given filter or filters.
*
Note that these filters will be applied in addition to the default filters, if specified.
* Any type under the specified base packages which matches a given filter will be included,
* even if it does not match the default filters (i.e. is not annotated with {@code @Component}).
* @see #resourcePattern()
* @see #useDefaultFilters()
*/
Filter[] includeFilters() default {};
/**
* Specifies which types are not eligible for component scanning.
* @see #resourcePattern
*/
Filter[] excludeFilters() default {};
/**
* Specify whether scanned beans should be registered for lazy initialization.
*
Default is {@code false}; switch this to {@code true} when desired.
* @since 4.1
*/
boolean lazyInit() default false;
/**
* Declares the type filter to be used as an {@linkplain ComponentScan#includeFilters
* include filter} or {@linkplain ComponentScan#excludeFilters exclude filter}.
*/
@Retention(RetentionPolicy.RUNTIME)
@Target({})
@interface Filter {
/**
* The type of filter to use.
*
Default is {@link FilterType#ANNOTATION}.
* @see #classes
* @see #pattern
*/
FilterType type() default FilterType.ANNOTATION;
/**
* Alias for {@link #classes}.
* @see #classes
*/
@AliasFor("classes")
Class[] value() default {};
/**
* The class or classes to use as the filter.
*
The following table explains how the classes will be interpreted
* based on the configured value of the {@link #type} attribute.
*
* {@code FilterType} Class Interpreted As {@link FilterType#ANNOTATION ANNOTATION}
* the annotation itself {@link FilterType#ASSIGNABLE_TYPE ASSIGNABLE_TYPE}
* the type that detected components should be assignable to {@link FilterType#CUSTOM CUSTOM}
* an implementation of {@link TypeFilter}
* When multiple classes are specified, OR logic is applied
* — for example, "include types annotated with {@code @Foo} OR {@code @Bar}".
*
Custom {@link TypeFilter TypeFilters} may optionally implement any of the
* following {@link org.springframework.beans.factory.Aware Aware} interfaces, and
* their respective methods will be called prior to {@link TypeFilter#match match}:
*
* - {@link org.springframework.context.EnvironmentAware EnvironmentAware}
* - {@link org.springframework.beans.factory.BeanFactoryAware BeanFactoryAware}
*
- {@link org.springframework.beans.factory.BeanClassLoaderAware BeanClassLoaderAware}
*
- {@link org.springframework.context.ResourceLoaderAware ResourceLoaderAware}
*
* Specifying zero classes is permitted but will have no effect on component
* scanning.
* @since 4.2
* @see #value
* @see #type
*/
@AliasFor("value")
Class[] classes() default {};
/**
* The pattern (or patterns) to use for the filter, as an alternative
* to specifying a Class {@link #value}.
*
If {@link #type} is set to {@link FilterType#ASPECTJ ASPECTJ},
* this is an AspectJ type pattern expression. If {@link #type} is
* set to {@link FilterType#REGEX REGEX}, this is a regex pattern
* for the fully-qualified class names to match.
* @see #type
* @see #classes
*/
String[] pattern() default {};
}
}