@Component @Repository @Service Complete Example
· in real life, at DAO and manager layer we often have separate classes and interfaces.
· Interface for defining the contract, and classes for defining the implementations of contracts. Where to use these annotations
Always use these annotations over concrete classes; not over interfaces.
· Working of all 3 are same
· But Using specific type of stereotype for specific type of Component is Recommended
@Component à Use in Bo, Bean Classes
@Repository à Use in DAO classes
@Service à Use in Service Layer classes
Example
StudentBo.java
package satya.bo;
import org.springframework.stereotype.Component;
@Component("bo")
public class StudentBo {
private int id;
private String name;
private String address;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public void getData(){
System.out.println("======STUDENT DATA ===========");
System.out.println(getId()+"\n"+getName()+"\n"+getAddress());
}
}
StudentDAO.java
package satya.dao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import satya.bo.StudentBo;
@Repository("dao")
public class StudentDAO {
@Autowired
StudentBo bo;
public void getData(){
bo.getData();
}
}
StudentService.java
package satya.service;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import satya.dao.StudentDAO;
@Service("service")
public class StudentService {
@Autowired
StudentDAO dao;
public void getData(){
dao.getData();
}
}
StudentMain.java
package satya;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import satya.bo.StudentBo;
import satya.service.StudentService;
public class StudentMain {
public static void main(String[] args) {
ApplicationContext context=new ClassPathXmlApplicationContext("satya/spring.xml");
StudentService ob = (StudentService)context.getBean("service");
ob.getData();
}
}
Spring.xml
<?xml version="1.0" encoding="UTF-8"?>
<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-3.2.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.2.xsd">
<!-- 1. Activate Annotations in XML -->
<context:annotation-config />
<context:component-scan base-package="satya.bo" />
<context:component-scan base-package="satya.dao" />
<context:component-scan base-package="satya.service"></context:component-scan>
<bean id="bo" class="satya.bo.StudentBo">
<property name="id" value="100"></property>
<property name="name" value="Satya"></property>
<property name="address" value="VIJAYAWADA"></property>
</bean>
</beans>
Output
======STUDENT DATA ===========
100
Satya
VIJAYAWADA