Using ApplicationContextAware in Spring

In this chapter, we will show you a short hint about how you can access your Spring-ApplicationContext from everywhere in your Application. We’ll provide our beans with access to the ApplicationContext object by implementing the ApplicationContextAware interface. We’ll also use BeanNameAware interface to get the name of the bean configured in the Spring XML.

WHY ApplicationContextAware?

Imagine we have an application (e.g. a web or Swing-application) which we now want to be Spring-enabled. Ok, we add the Spring libraries(spring.jar) and the Configuration-file(spring.xml) and create our Spring-beans. But there are still some old class-files which you can’t use in this way. These files still need access to the Spring-Honeypot where all the goodies exist and you don’t want to redesign your application.

Popular Tutorials

First, create the class “ApplicationContextProvider (Triangle class)”. This class implements the ApplicationContextAware. A bean which implements the ApplicationContextAware-interface and is deployed into the context will be called back on the creation of the bean, using the interface’s setApplicationContext(…) method, and provided with a reference to the context, which may be stored for later interaction with the context.

In this tutorial, you will see an example of using ApplicationContextAware. The ApplicationContextAware is used when an object required.

Triangle.java

package com.dineshonjava.sdnext.contextAware.tutorial;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanNameAware;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

public class Triangle implements ApplicationContextAware, BeanNameAware
{
 private Point pointA;
 private Point pointB;
 private Point pointC;
 private ApplicationContext context = null;
 
 /**
  * @param pointA the pointA to set
  */
 public void setPointA(Point pointA) {
  this.pointA = pointA;
 }

 /**
  * @param pointB the pointB to set
  */
 public void setPointB(Point pointB) {
  this.pointB = pointB;
 }

 /**
  * @param pointC the pointC to set
  */
 public void setPointC(Point pointC) {
  this.pointC = pointC;
 }

 public void draw()
 {
System.out.println("PointA is ("+pointA.getX()+", "+pointA.getY()+")");
System.out.println("PointB is ("+pointB.getX()+", "+pointB.getY()+")");
System.out.println("PointC is ("+pointC.getX()+", "+pointC.getY()+")");
 }

 @Override
 public void setApplicationContext(ApplicationContext context) throws BeansException
 {
  this.context = context;
 }

 @Override
 public void setBeanName(String beanName)
 {
  System.out.println("Bean name is: "+beanName);
 }
}

Point.java

package com.dineshonjava.sdnext.contextAware.tutorial;

public class Point
{
 private int x;
 private int y;
 /**
  * @return the x
  */
 public int getX() {
  return x;
 }
 /**
  * @param x the x to set
  */
 public void setX(int x) {
  this.x = x;
 }
 /**
  * @return the y
  */
 public int getY() {
  return y;
 }
 /**
  * @param y the y to set
  */
 public void setY(int y) {
  this.y = y;
 }
}

spring.xml

<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.springframework.org/schema/beans" xsi:schemalocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
 <bean autowire="byName" class="com.dineshonjava.sdnext.contextAware.tutorial.Triangle" id="triangle"></bean>
  
<bean class="com.dineshonjava.sdnext.contextAware.tutorial.Point" id="pointA">
  <property name="x" value="0"></property>
  <property name="y" value="0"></property>
</bean>
  
<bean class="com.dineshonjava.sdnext.contextAware.tutorial.Point" id="pointB">
  <property name="x" value="-20"></property>
  <property name="y" value="0"></property>
</bean>
  
<bean class="com.dineshonjava.sdnext.contextAware.tutorial.Point" id="pointC">
   <property name="x" value="20"></property>
   <property name="y" value="0"></property>
</bean>
</beans>

DrawingApp.java

package com.sdnext.contextAware.tutorial;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * @author Dinesh Rajput
 *
 */
public class DrawingApp 
{
 /**
  * @param args
  */
 public static void main(String[] args) 
 {
ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
Triangle triangle = (Triangle) context.getBean("triangle");
triangle.draw();
 }
}

Output:

Jun 30, 2012 3:28:54 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@145d068: startup date [Sat Jun 30 15:28:54 IST 2012]; root of context hierarchy

Jun 30, 2012 3:28:55 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

INFO: Loading XML bean definitions from class path resource [spring.xml]

Jun 30, 2012 3:28:55 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons

INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@f11404: defining beans [triangle,pointA,pointB,pointC]; root of factory hierarchy

Bean name is: triangle
PointA is (0, 0)
PointB is (-20, 0)
PointC is (20, 0)

What is Need for Using ApplicationContextAware in Application?

In the previous chapter, we have seen that we create application context object via using a configuration file(spring.xml) but we did this only one time of the application context object using a configuration file (spring.xml) for an entire application.

If we done one time creating application context object and also one time creating triangle bean through the getBean() method because its have “singleton” scope and beans pointA, pointB & pointC are also populated along with triangle bean only one time when triangle bean is initialized even though pointA, pointB & pointC are the prototypes in scope.

After that, we can not create a new bean pointA, pointB & pointC objects without creating triangle bean in the Triangle class or anywhere else except the main app(DrawingApp.java).

And there is some situation we want to use application context object anywhere else like in bean class(in Triangle class). Suppose the Triangle bean need to application context object for some reasons.

Suppose If we want to create new beans pointA, pointB & pointC in triangle class then we have to declare pointA, pointB & pointC beans as prototype bean scope. Now we have to need to access an applicationContext object in the triangle bean class so because of this we are used ApplicationContextAware interface and this interface is implements by the Triangle bean class for accessing application context object from overriding the following method of the ApplicationContextAware interface.

@override
public void setApplicationContext(ApplicationContext context) throws BeansException
{
  this.context = context;
}

In Next Chapter, we will discuss Bean Definition Inheritance in Spring in Application.

Spring Related Topics you may like

7 Comments

Manish June 30, 2012

bhai kuch explain bhi kar diya hota hm jaise novice people ke liye.
why should we , when should we use this applicationcontextaware.
Dinesh Rajput June 30, 2012

Ok manish thanks for comment and next i will try to explain clearly ..:)
Anonymous June 30, 2012

good informative about the applicationcontextaware
manish July 1, 2012

yaar thanks ki koi baat hi ni hai tum kuch acha hi kar rahe ho
fdsa November 18, 2018

Bad english. Grammatical errors.
Dinesh Rajput December 6, 2018

Thanks for your feedback, I have corrected some of them.
infoj March 8, 2019

ApplicationContextAware interface can be used-

To inject prototype scoped bean in a singleton bean.
To access Spring bean from some other code which is not within the Spring container.

WHY ApplicationContextAware?

What is Need for Using ApplicationContextAware in Application?

Share this:

Related Posts

About The Author

Dinesh Rajput

7 Comments