In our Drawing Application class(DrawingApp.java) we are using draw() method of the Triangle class. As below-
ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml"); Triangle triangle = (Triangle) context.getBean("triangle"); triangle.draw();
Here Drawing Application knows that it using draw() method of Triangle bean. If we want to use the draw() method of the circle class then we have to write the following code in the Drawing Application-
ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml"); Circle circle= (Circle) context.getBean("circle"); circle.draw();
If want to use the true power of spring framework then we have to use the coding to interface technique. In coding to interface Drawing Application(DrawingApp.java) does not care about that the draw() method of which classes is called. Both classes just implements the Shape interface with one method draw(). And after that Drawing Class have the following code-
ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml"); Shape shape = (Shape) context.getBean("shape"); shape.draw();
Lets see the full running example about the Coding to interface.
Shape.java
package com.dineshonjava.sdnext.interfaceCoding.tutorial; public interface Shape { void draw(); }
Triangle.java
package com.dineshonjava.sdnext.interfaceCoding.tutorial; public class Triangle implements Shape { 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("Drawing Triangle"); 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()+")"); } }
Circle.java
package com.dineshonjava.sdnext.interfaceCoding.tutorial; public class Circle implements Shape { private Point center; /** * @param center the center to set */ public void setCenter(Point center) { this.center = center; } @Override public void draw() { System.out.println("Circle is drawn of center ("+center.getX()+", "+center.getY()+")"); } }
Point.java
package com.dineshonjava.sdnext.interfaceCoding.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:aop="http://www.springframework.org/schema/aop" xmlns:p="http://www.springframework.org/schema/p" xmlns:> If every thing is OK then run the following Drawing Application draw a shape using draw() method of shape interface. DrawingApp.javapackage com.dineshonjava.sdnext.interfaceCoding.tutorial; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; /** * @author Dinesh * */ public class DrawingApp { /** * @param args */ public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml"); Shape shape = (Shape) context.getBean("triangle"); shape.draw(); } }Its draw a triangle.
Output:Jul 8, 2012 7:02:58 PM org.springframework.context.support.AbstractApplicationContext prepareRefreshINFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@ab50cd: startup date [Sun Jul 08 19:02:57 IST 2012]; root of context hierarchyJul 8, 2012 7:02:58 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitionsINFO: Loading XML bean definitions from class path resource [spring.xml]Jul 8, 2012 7:02:59 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletonsINFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@14c1103: defining beans [triangle,circle,pointA,pointB,pointC,center]; root of factory hierarchyDrawing Triangle
PointA is (0, 0)
PointB is (-20, 0)
PointC is (20, 0)
If we want draw a circle the execute the following Drawing Application.
DrawingApp.javapackage com.dineshonjava.sdnext.interfaceCoding.tutorial; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; /** * @author Dinesh * */ public class DrawingApp { /** * @param args */ public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml"); Shape shape = (Shape) context.getBean("circle"); shape.draw(); } }
Its draw a circle.Output:Jul 8, 2012 7:05:11 PM org.springframework.context.support.AbstractApplicationContext prepareRefreshINFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@ab50cd: startup date [Sun Jul 08 19:05:11 IST 2012]; root of context hierarchyJul 8, 2012 7:05:11 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitionsINFO: Loading XML bean definitions from class path resource [spring.xml]Jul 8, 2012 7:05:11 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletonsINFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@14c1103: defining beans [triangle,circle,pointA,pointB,pointC,center]; root of factory hierarchyCircle is drawn of center (10, 10)
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