Monday, July 22, 2013

13-Bean-Definition-Inheritance

In spring you can inherit the bean definition using keyword “parent”
      <bean id="parentTriangle" class="org.yash.watertechsol.Triangle">
            <property name="pointA" ref="pointA"></property>
      </bean>    
           
      <bean id="triangle" class="org.yash.watertechsol.Triangle" parent="parentTriangle">
            <property name="pointB" ref="pointB"></property>
            <property name="pointC" ref="pointC"></property>
      </bean>

If you don’t want to initialize your parent class just want to use as template, then you have property class “abstract=true”, in this case spring do not create beam for that id it can be only used as template. Child beans have to inherit this bean.

      <bean id="parentTriangle" class="org.yash.watertechsol.Triangle" abstract="true">
            <property name="pointA" ref="pointA"></property>
      </bean>    

You can also add list or collection classes in bean configuration.
      <bean id="parentTriangle" class="org.yash.watertechsol.Triangle" abstract="true">
            <property name="points">
                  <list>
                        <ref bean="pointA" />
                  </list>
            </property>
      </bean>    

You can merge parent list in child bean list. If you won’t merge then parent list over written by child bean.
      <bean id="parentTriangle" class="org.yash.watertechsol.Triangle" abstract="true">
            <property name="points">
                  <list>
                        <ref bean="pointA" />
                  </list>
            </property>
      </bean>
      <bean id="triangle" class="org.yash.watertechsol.Triangle" parent="parentTriangle">
            <property name="points">
                  <list merge="true">
                        <ref bean="pointB" />
                  </list>
            </property>      
      </bean>

Drawing.java
package org.yash.watertechsol;

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


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

Point.java
package org.yash.watertechsol;

public class Point {
      private int x;
      private int y;
     
      public int getX() {
            return x;
      }
      public void setX(int x) {
            this.x = x;
      }
      public int getY() {
            return y;
      }
      public void setY(int y) {
            this.y = y;
      }
}

Triangle.java
package org.yash.watertechsol;

import java.util.List;

public class Triangle {
     
      private List<Point> points;

      public void draw(){
           
            for(Point point:points){
                  System.out.println(point.getX() +", "+point.getY());
            }
      }

      public void setPoints(List<Point> points) {
            this.points = points;
      }

      public List<Point> getPoints() {
            return points;
      }
}

spring.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN" "http://www.springframework.org/dtd/spring-beans-2.0.dtd">

<beans>

      <bean id="parentTriangle" class="org.yash.watertechsol.Triangle" abstract="true">
            <property name="points">
                  <list>
                        <ref bean="pointA" />
                  </list>
            </property>
      </bean>    
           
      <bean id="triangle" class="org.yash.watertechsol.Triangle" parent="parentTriangle">
            <property name="points">
                  <list merge="true">
                        <ref bean="pointB" />
                  </list>
            </property>      
      </bean>

     
      <bean id ="pointA" class="org.yash.watertechsol.Point">
            <property name="x" value="0" />
            <property name="y" value="0" />
      </bean>
     
      <bean id ="pointB" class="org.yash.watertechsol.Point">
            <property name="x" value="-20" />
            <property name="y" value="0" />
      </bean>

      <bean id ="pointC" class="org.yash.watertechsol.Point">
            <property name="x" value="0" />
            <property name="y" value="20" />
      </bean>    
</beans>

*********************************************

Triangle.java
package org.yash.watertechsol;

public class Triangle {
     
      private Point pointA;
      private Point pointB;
      private Point pointC;
     
      public Point getPointA() {
            return pointA;
      }

      public void setPointA(Point pointA) {
            this.pointA = pointA;
      }

      public Point getPointB() {
            return pointB;
      }

      public void setPointB(Point pointB) {
            this.pointB = pointB;
      }

      public Point getPointC() {
            return pointC;
      }

      public void setPointC(Point pointC) {
            this.pointC = pointC;
      }

      public void draw(){
            System.out.println("Point A = (" + getPointA().getX()+", "+getPointA().getY()+")");
            System.out.println("Point B = (" + getPointB().getX()+", "+getPointB().getY()+")");
            System.out.println("Point C = (" + getPointC().getX()+", "+getPointC().getY()+")");
      }
}

spring.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN" "http://www.springframework.org/dtd/spring-beans-2.0.dtd">

<beans>

      <bean id="parentTriangle" class="org.yash.watertechsol.Triangle">
            <property name="pointA" ref="pointA"></property>
      </bean>    
           
      <bean id="triangle" class="org.yash.watertechsol.Triangle" parent="parentTriangle">
            <property name="pointB" ref="pointB"></property>
            <property name="pointC" ref="pointC"></property>
      </bean>

     
      <bean id ="pointA" class="org.yash.watertechsol.Point">
            <property name="x" value="0" />
            <property name="y" value="0" />
      </bean>
     
      <bean id ="pointB" class="org.yash.watertechsol.Point">
            <property name="x" value="-20" />
            <property name="y" value="0" />
      </bean>

      <bean id ="pointC" class="org.yash.watertechsol.Point">
            <property name="x" value="0" />
            <property name="y" value="20" />
      </bean>    

</beans>

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