Spring Filter components in auto scanning
In this Spring auto component scanning tutorial, you learn about how to make Spring auto scan your components. In this article, we show you how to do component filter in auto scanning process.
1. Filter component – include
See following example to use Spring “filtering” to scan and register components’ name which matched defined “regex”, even the class is not annotated with @Component.
DAO layer
package com.mkyong.customer.dao;
public class CustomerDAO
{
@Override
public String toString() {
return "Hello , This is CustomerDAO";
}
}
Service layer
package com.mkyong.customer.services;
import org.springframework.beans.factory.annotation.Autowired;
import com.mkyong.customer.dao.CustomerDAO;
public class CustomerService
{
@Autowired
CustomerDAO customerDAO;
@Override
public String toString() {
return "CustomerService [customerDAO=" + customerDAO + "]";
}
}
Spring filtering.
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-2.5.xsd">
<context:component-scan base-package="com.mkyong" >
<context:include-filter type="regex"
expression="com.mkyong.customer.dao.*DAO.*" />
<context:include-filter type="regex"
expression="com.mkyong.customer.services.*Service.*" />
</context:component-scan>
</beans>
Run it
package com.mkyong.common;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.mkyong.customer.services.CustomerService;
public class App
{
public static void main( String[] args )
{
ApplicationContext context =
new ClassPathXmlApplicationContext(new String[] {"Spring-AutoScan.xml"});
CustomerService cust = (CustomerService)context.getBean("customerService");
System.out.println(cust);
}
}
Output
CustomerService [customerDAO=Hello , This is CustomerDAO]
In this XML filtering, all files’s name contains DAO or Service (*DAO.*, *Services.*) word will be detect and register in Spring container.
2. Filter component – exclude
On the other hand, you can also exclude specified components, to avoid Spring to detect and register it in Spring container.
Exclude those files annotated with @Service.
<context:component-scan base-package="com.mkyong.customer" >
<context:exclude-filter type="annotation"
expression="org.springframework.stereotype.Service" />
</context:component-scan>
Exclude those files name contains DAO word.
<context:component-scan base-package="com.mkyong" >
<context:exclude-filter type="regex"
expression="com.mkyong.customer.dao.*DAO.*" />
</context:component-scan>
Hi mkyong,
I think you forgot to put @Component in DAO and SERVICE class. Because as per tutorial “Spring Auto scanning components”, it should annotate to search components in base package.
Please confirm.
Thats why we are using includeFilter, lets say suppose we are working with 3rd party classes where we dont have any source code to modify the class and annotate with @Component, then we can use includeFilter
My experience is that autowiring and component scan doesn’t scale up to larger and more complex systems. It is nice for tutorials and small experiments, but having an explicit written application context is much more maintainable than some crappy magic.
ya..agreed with your point, personally i more prefer the mature Spring XML support 🙂
web site is very excellent for under standing the concept ….
so thank you sir