Introduction to Spring - Spring Enterprise Recipes: A Problem Solution Approach - page 31

The @Component annotation is the basic stereotype for denoting components of general purposes.
Actually, there are other specific stereotypes denoting components in different layers. First, the
@Repository stereotype denotes a DAO component in the persistence layer.

package com.apress.springenterpriserecipes.sequence;

import org.springframework.stereotype.Repository;

@Repository
public class SequenceDaoImpl implements SequenceDao {
...
}

Then the @Service stereotype denotes a service component in the service layer.

package com.apress.springenterpriserecipes.sequence;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class SequenceService {

@Autowired
private SequenceDao sequenceDao;
...
}

There's another component stereotype, @Controller , which denotes a controller component in the
presentation layer.

Filtering Components to Scan
By default, Spring will detect all classes annotated with @Component , @Repository , @Service , @Controller ,
or your custom annotation type that is itself annotated with @Component . You can customize the scan by
applying one or more include/exclude filters.
Spring supports four types of filter expressions. The annotation and assignable types are for you
to specify an annotation type and a class/interface for filtering. The regex and aspectj types allow you to
specify a regular expression and an AspectJ pointcut expression for matching the classes. You can also
disable the default filters with the use-default-filters attribute.
For example, the following component scan includes all classes whose name contains the word Dao
or Service , and excludes the classes with the @Controller annotation:

<beans ...>
<context:component-scan base-package= ➥

"com.apress.springenterpriserecipes.sequence">
<context:include-filter type=" regex"
expression="com\.apress\.springenterpriserecipes\.sequence\..*Dao.*" />
<context:include-filter type=" regex"
expression="com\.apress\.springenterpriserecipes\.sequence\.. ➥

*Service.*" />