org.springframework.context.annotation

Annotation Type ComponentScan

@Retention(value=RUNTIME)
 @Target(value=TYPE)
 @Documented
 @Repeatable(value=ComponentScans.class)
public @interface ComponentScan

Configures component scanning directives for use with @Configuration classes. Provides support parallel with Spring XML's <context:component-scan> element.

Either basePackageClasses() or basePackages() (or its alias value()) may be specified to define specific packages to scan. If specific packages are not defined, scanning will occur from the package of the class that declares this annotation.

Note that the <context:component-scan> element has an annotation-config attribute; however, this annotation does not. This is because in almost all cases when using @ComponentScan, default annotation config processing (e.g. processing @Autowired and friends) is assumed. Furthermore, when using AnnotationConfigApplicationContext, annotation config processors are always registered, meaning that any attempt to disable them at the @ComponentScan level would be ignored.

See @Configuration's Javadoc for usage examples.

Since:

3.1

Author:

Chris Beams, Juergen Hoeller, Sam Brannen

See Also:

Configuration

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
Class<?>[]	basePackageClasses Type-safe alternative to basePackages() for specifying the packages to scan for annotated components.
String[]	basePackages Base packages to scan for annotated components.
ComponentScan.Filter[]	excludeFilters Specifies which types are not eligible for component scanning.
ComponentScan.Filter[]	includeFilters Specifies which types are eligible for component scanning.
boolean	lazyInit Specify whether scanned beans should be registered for lazy initialization.
Class<? extends BeanNameGenerator>	nameGenerator The BeanNameGenerator class to be used for naming detected components within the Spring container.
String	resourcePattern Controls the class files eligible for component detection.
ScopedProxyMode	scopedProxy Indicates whether proxies should be generated for detected components, which may be necessary when using scopes in a proxy-style fashion.
Class<? extends ScopeMetadataResolver>	scopeResolver The ScopeMetadataResolver to be used for resolving the scope of detected components.
boolean	useDefaultFilters Indicates whether automatic detection of classes annotated with @Component @Repository, @Service, or @Controller should be enabled.
String[]	value Alias for basePackages().

Element Detail

value

@AliasFor(value="basePackages")
public abstract String[] value

Alias for basePackages().

Allows for more concise annotation declarations if no other attributes are needed — for example, @ComponentScan("org.my.pkg") instead of @ComponentScan(basePackages = "org.my.pkg").

Default:

{}

basePackages

@AliasFor(value="value")
public abstract String[] basePackages

Base packages to scan for annotated components.

value() is an alias for (and mutually exclusive with) this attribute.

Use basePackageClasses() for a type-safe alternative to String-based package names.

Default:

{}

basePackageClasses

public abstract Class<?>[] basePackageClasses

Type-safe alternative to 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.

Default:

{}

nameGenerator

public abstract Class<? extends BeanNameGenerator> nameGenerator

The BeanNameGenerator class to be used for naming detected components within the Spring container.

The default value of the BeanNameGenerator interface itself indicates that the scanner used to process this @ComponentScan annotation should use its inherited bean name generator, e.g. the default AnnotationBeanNameGenerator or any custom instance supplied to the application context at bootstrap time.

See Also:

AnnotationConfigApplicationContext.setBeanNameGenerator(BeanNameGenerator)

Default:

org.springframework.beans.factory.support.BeanNameGenerator.class

scopeResolver

public abstract Class<? extends ScopeMetadataResolver> scopeResolver

The ScopeMetadataResolver to be used for resolving the scope of detected components.

Default:

org.springframework.context.annotation.AnnotationScopeMetadataResolver.class

scopedProxy

public abstract ScopedProxyMode scopedProxy

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 scopeResolver().

See Also:

ClassPathBeanDefinitionScanner.setScopedProxyMode(ScopedProxyMode)

Default:

org.springframework.context.annotation.ScopedProxyMode.DEFAULT

resourcePattern

public abstract String resourcePattern

Controls the class files eligible for component detection.

Consider use of includeFilters() and excludeFilters() for a more flexible approach.

Default:

"**/*.class"

useDefaultFilters

public abstract boolean useDefaultFilters

Indicates whether automatic detection of classes annotated with @Component @Repository, @Service, or @Controller should be enabled.

Default:

true

includeFilters

public abstract ComponentScan.Filter[] includeFilters

Specifies which types are eligible for component scanning.

Further narrows the set of candidate components from everything in 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 @Component).

See Also:

resourcePattern(), useDefaultFilters()

Default:

{}

excludeFilters

public abstract ComponentScan.Filter[] excludeFilters

Specifies which types are not eligible for component scanning.

See Also:

resourcePattern()

Default:

{}

lazyInit

public abstract boolean lazyInit

Specify whether scanned beans should be registered for lazy initialization.

Default is false; switch this to true when desired.

Since:

4.1

Default:

false