Dinesh on Java

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In the previous chapter you have seen that how to inject on object been(point) to another bean(triangle) with using setter-injection methodology. Here we discuss same example with the concept of the injecting inner bean. Inner Bean means bean with in the bean i.e one bean(point) defined inside the another bean(triangle).

In the bean configuration file(spring.xml) there are four beans(ids are triangle, pointA, pointB and pointC) defined in the previous chapter suppose that beans (pointB and pointC) of the Point class are using only for triangle bean definition then there no need to defined the Point been in separately in the  bean configuration file(spring.xml) and pointA is the common point using by different shape as Circle, Rectangle etc si its defined separately in the  bean configuration file(spring.xml). The best idea at this situation we have to defined Point bean ‘s definition as inner bean definition with in the Triangle bean.

<bean class="com.dineshonjava.sdnext.innerBean.tutorial.Triangle" id="triangle">
   <property name="pointA" ref="pointA"></property>
   <property name="pointB">
      <bean class="com.dineshonjava.sdnext.innerBean.tutorial.Point">
  <property name="x" value="-20"></property>
  <property name="y" value="0"></property>
      </bean>
   </property>
   <property name="pointC">
      <bean class="com.dineshonjava.sdnext.innerBean.tutorial.Point">
 <property name="x" value="20"></property>
 <property name="y" value="0"></property>
      </bean>
   </property>
</bean>
<bean class="com.dineshonjava.sdnext.innerBean.tutorial.Point" id="pointA">
   <property name="x" value="0"></property>
   <property name="y" value="0"></property>
</bean>

Triangle.java

package com.dineshonjava.sdnext.innerBean.tutorial;

public class Triangle 
{
 private Point pointA;
 private Point pointB;
 private Point pointC;
 
 /**
  * @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()+")");
 }
}

Point.java

package com.dineshonjava.sdnext.innerBean.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 class="com.sdnext.innerBean.tutorial.Triangle" triangle="triangle" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:p="http://www.springframework.org/schema/p" xmlns:>
DrawingApp.java
package com.dineshonjava.sdnext.innerBean.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();
 }

}

 

Run the application and we get same output as previous


output:
Jun 23, 2012 12:30:25 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@ab50cd: startup date [Sat Jun 23 12:30:25 IST 2012]; root of context hierarchy
Jun 23, 2012 12:30:26 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [spring.xml]
Jun 23, 2012 12:30:26 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@14c1103: defining beans [triangle,zeroPoint,Point2,Point3]; root of factory hierarchy
PointA is (0, 0)

PointB is (-20, 0)

PointC is (20, 0)