In this article, we will explore about event handling Spring application. Spring Framework also provide an another feature to promote loose coupling ,which is Application Event handling. Using Events, an Event publisher object can communicate with other objects without even knowing which object is listen.and event listener can work to event without knowing which object publish the events. Publisher Object that object ,who publish the event or call the event and Listener always listen the events that are occurs.
Circle.java
package com.dineshonjava.sdnext.eventHandling.tutorial; import javax.annotation.Resource; import org.springframework.context.ApplicationEventPublisher; import org.springframework.context.ApplicationEventPublisherAware; import org.springframework.context.MessageSource; import org.springframework.stereotype.Controller; /** * @author Dinesh Rajput * */ @Controller public class Circle implements ApplicationEventPublisherAware { private Point center; private ApplicationEventPublisher publisher; /** * @param center the center to set */ @Resource(name="pointB") public void setCenter(Point center) { this.center = center; } public void draw() { System.out.println("Circle is Drawn"); DrawEvent drawEvent = new DrawEvent(this); publisher.publishEvent(drawEvent); } @Override public void setApplicationEventPublisher(ApplicationEventPublisher publisher) { this.publisher = publisher; } }
Point.java
package com.dineshonjava.sdnext.eventHandling.tutorial; /** * @author Dinesh Rajput * */ 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; } }
MyEventListener.java
package com.dineshonjava.sdnext.eventHandling.tutorial; import org.springframework.context.ApplicationEvent; import org.springframework.context.ApplicationListener; import org.springframework.stereotype.Component; @Component public class MyEventListener implements ApplicationListener { @Override public void onApplicationEvent(ApplicationEvent event) { System.out.println(event.toString()); } }
DrawEvent.java
package com.dineshonjava.sdnext.eventHandling.tutorial; import org.springframework.context.ApplicationEvent; public class DrawEvent extends ApplicationEvent { /** * Dinesh Rajput */ private static final long serialVersionUID = 6973014356268900607L; public DrawEvent(Object source) { super(source); } public String toString() { return "Draw event occurred"; } }
spring.xml
<beans xmlns:context="http://www.springframework.org/schema/context" 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.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <context:annotation-config></context:annotation-config> <bean class="com.sdnext.dineshonjava.eventHandling.tutorial.Point" id="pointB"> <property name="x" value="10"></property> <property name="y" value="20"></property> </bean> <context:component-scan base-package="com.sdnext.dineshonjava.eventHandling.tutorial"></context:component-scan> </beans>
DrawingApp.java
package com.dieshonjava.sdnext.eventHandling.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"); Circle circle = (Circle)context.getBean("circle"); circle.draw(); } }
Circle is Drawn
Draw event occurred
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