Daily Archives: September 2, 2016

Application Listener

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Event Handling requires 3 Things

  1. Event Publisher
  2. Event Listener
  3. Event

CustomEvent.java(Event)

import org.springframework.context.ApplicationEvent;

public class CustomEvent extends ApplicationEvent
{
	public CustomEvent(Object source) 
        {
		super(source);
	}	

	public String toString()
	{
		return "Custom Message from Custom Event";
	}
}

CustomEventListener.java(Event Listener)

import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;

@Component
public class CustomEventListener implements ApplicationListener
{
	@Override
	public void onApplicationEvent(ApplicationEvent event) {		
		System.out.println(event.toString());
	}
}

Circle.java(Event Publisher)

import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;

@Component
public class Circle implements Shape, ApplicationEventPublisherAware
{			
	private ApplicationEventPublisher publisher;
	
	@Override
	public void drawShape() {	
		CustomEvent objCustEvent = new CustomEvent(this); 
		publisher.publishEvent(objCustEvent);
	}
	
	@Override
	public void setApplicationEventPublisher(ApplicationEventPublisher publisher) {
		this.publisher = publisher;
	}

	public ApplicationEventPublisher getPublisher() {
		return publisher;
	}

	public void setPublisher(ApplicationEventPublisher publisher) {
		this.publisher = publisher;
	}	
}

Spring Annotations 2

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Java Specification Request JSR 250

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-2.5.xsd
		http://www.springframework.org/schema/context 
		http://www.springframework.org/schema/context/spring-context-2.5.xsd">	
	<bean id="pointC" class="com.mugil.shapes.Point">
		<property name="x" value="20"/>
		<property name="y" value="0"/>
	</bean> 	
	<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
		<property name="location" value="constant.properties"></property>
	</bean>	
	<bean class="com.mugil.shapes.Circle" id="circleId">
	</bean>	
	<context:annotation-config/>
</beans>

circle.java

public class Circle implements Shape{		
	private Point center;
	
	@Override
	public void drawShape() {
		System.out.println("Shape of Circle ");
		System.out.println("Center of Cirlce "+ getCenter().getX() + " - " + getCenter().getY());
	}

	public Point getCenter() {
		return center;
	}

	@Resource(name="pointC")
	public void setCenter(Point center) {
		this.center = center;
	}
	
	@PostConstruct
	public void initilizeMe() 
	{
		System.out.println("Initialized");
	}
	
	@PreDestroy
	public void destroyMe() 
	{
		System.out.println("Derstroyed");
	}
}

If name is not specified after the @Resource it will look for same name matching bean in the spring.xml file.

@PostConstruct and @PreDestroy will be called when circle bean is initialized and destroyed

Defining Bean using Annotations
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-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.mugil.shapes"/>
</beans>

circle.java

@Component
public class Circle implements Shape
{	
.
.
}

drawingApp.java

public class DrawingApp {
	public static void main(String[] args)  {
		 AbstractApplicationContext objContext = new ClassPathXmlApplicationContext("spring1.xml");
		 objContext.registerShutdownHook();
		Shape objShape =  (Shape)objContext.getBean("circle");
.
.
}

Using MessageSource
spring.xml

<bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
		<property name="basenames">
			<list>
				<value>constant</value>
			</list>
		</property>
	</bean>

constant.properties

TestMessage=Mugil

DrawingApp.java

 AbstractApplicationContext objContext = new ClassPathXmlApplicationContext("spring1.xml");
System.out.println(objContext.getMessage("TestMessage", null, "Default Message", null));

Output

 Mugil

Using instance of Message Source in Bean Class
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-2.5.xsd
		http://www.springframework.org/schema/context 
		http://www.springframework.org/schema/context/spring-context-2.5.xsd">
<bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
		<property name="basenames">
			<list>
				<value>constant</value>
			</list>
		</property>
	</bean>
	<context:annotation-config/>
	<context:component-scan base-package="com.mugil.shapes"/>
</beans>

circle.java

@Component
public class Circle implements Shape{		
	private Point center;
	
	@Autowired
	private MessageSource messageSource;	
	
	@Override
	public void drawShape() {
		System.out.println("Shape of Circle ");		
		System.out.println(this.messageSource.getMessage("TestMessage", null, "Vannan", null));
	}

	public Point getCenter() {
		return center;
	}

	@Resource(name="pointC")
	public void setCenter(Point center) {
		this.center = center;
	}
	
	public MessageSource getMessageSource() {
		return messageSource;
	}

	public void setMessageSource(MessageSource messageSource) {
		this.messageSource = messageSource;
	}
	
}

this.messageSource.getMessage(“TestMessage”, null, “Vannan”, null)

Variable substitution in Message Source

circle.java

@Component
public class Circle implements Shape{		
	private Point center;
	
	@Autowired
	private MessageSource messageSource;
	
	
	@Override
	public void drawShape() {
		System.out.println("Center of Cirlce");		System.out.println(this.messageSource.getMessage("TestMessage2", new Object[]{center.getX(), center.getY()}, "Vannan", null));
	}
.
.
.
}

this.messageSource.getMessage(“TestMessage2”, new Object[]{center.getX(), center.getY()}, “Vannan”, null)

constant.properties

TestMessage=Mugil
TestMessage2=Center of Circle : ({0}, {1})