Skip to main content

Easy access to Spring ApplicationContext in any non bean class

Checkout the following class

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

/**
 *
 * @author intesar
 * Simple bean class which implements ApplicationContextAware interface
  */
@Component
public class SpringApplicationContextFactory implements ApplicationContextAware {

    static ApplicationContext ctx;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        ctx = applicationContext;
    }

    public static ApplicationContext getContext() {
        return ctx;
    }
}

When an ApplicationContext creates a class that implemetns the ApplicationContextAware interface, the class is provided with a reference to that ApplicationContext.

Note :    SpringApplicationContextFactory class can be declared using either Annotation or xml style

Usage : You might find this handy to access beans inside your Servlets, Portlets, or any other class which is not managed by Spring container

Sample Code :

SampleService service = (SampleService) SpringApplicationContextFactory.getContext().getBean("sampleServiceImpl");

Checkout Spring Documentation for more details

Comments

Unknown said…
Intesar,

Do you know of a course that teach the Spring framework at DePaul University?

Thanks!

Mohamed
SE
DePaul University
February 11, 2011 at 2:40 PM
Post a Comment

Popular posts from this blog

Access multiple Databases in JPA

According to JPA specification we can define multiple "persistence-unit" elements (i.e. like below) in persistence.xml file and can easily refer them inside Dao layers as this. public class PolarDaoImpl {     @PersistenceContext(unitName="PolarPU")     protected EntityManager entityManager; -- } public class BearDaoImpl {     @PersistenceContext(unitName="BearPU")     protected EntityManager entityManager; -- } Checkout sample persistence.xml <?xml version="1.0" encoding="UTF-8"?> <persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">     <!-- Database 1 -->     <persistence-unit name="PolarPU" transaction-type="RESOURCE_LOCAL">         <
3 comments
Read more

JPA 2 new feature @ElementCollection explained

@ElementCollection is new annotation introduced in JPA 2.0, This will help us get rid of One-Many and Many-One shitty syntax. Example 1: Stores list of Strings in an Entity @Entity public class Users implements Serializable {     private static final long serialVersionUID = 1L;     @Id     @GeneratedValue(strategy = GenerationType.AUTO)     private Long id;     @ElementCollection     private List<String> certifications = new ArrayList <String> ();     public Long getId() {         return id;     }     public void setId(Long id) {         this.id = id;     }     public List <String> getCertifications() {         return certifications;     }     public void setCertifications(List <String> certifications) {         this.certifications = certifications;     } .. }         Users u = new Users();         u.getCertifications().add("Sun Certified Java Programmer");         em.persist(u); Generated Tables    Users    Co
21 comments
Read more

Reuse JPA Entities as DTO

Note : Major design advantages of JPA Entities are they can detached and used across tiers and networks and later can by merged. Checkout this new way of querying entities in JPA 2.0 String ql = " SELECT new prepclass2.Employee (e.firstname, e.lastname) FROM Employee e "; List<Employee> dtos = em.createQuery(ql).getResultList(); The above query loads all Employee entities but with subset of data i.e. firstname, lastname. Employee entity looks like this. @Entity @Table(name="emp") public class Employee implements Serializable {     private static final long serialVersionUID = 1L;     @Id     @GeneratedValue(strategy = GenerationType.AUTO)     private Long id;     @Column     private String firstname;     @Column     private String lastname;     @Column     private String username;     @Column     private String street;     @Column     private String city;     @Column     private String state;     @Column     private String zipc
11 comments
Read more