Working with Bean

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spring.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
    <bean id="triangleId" class="com.mugil.shapes.Triangle"/>
</beans>

Triangle.java

package com.mugil.shapes;

public class Triangle {
	private String type;
	
	public String getType() {
		return type;
	}

	public void setType(String type) {
		this.type = type;
	}

	public void drawShape()
	{
		System.out.println("Shape of Triangle");
	}
}

Reading value of Bean by Application Context and Bean Factory

public class Shape 
{
   public static void main(String[] args) 
   {
	ApplicationContext objContext = new ClassPathXmlApplicationContext("spring1.xml");
	Triangle objTriangle1 =  (Triangle)objContext.getBean("triangleId");
	objTriangle1.drawShape();
		
		
	BeanFactory  objBeanFactory = new XmlBeanFactory(new FileSystemResource("spring.xml"));
	Triangle objTriangle2 =  (Triangle)objBeanFactory.getBean("triangleId");
	objTriangle2.drawShape();
    }
}

Constructor Initialization
Triangle.java

package com.mugil.shapes;

public class Triangle 
{
	private String type;

        public Triangle(String ptype)
	{
		this.type = ptype;
	}
	
        public void drawShape()
	{
		System.out.println("Shape of Triangle");
	}
}

The Index Specifies which variable in the Bean is Initialized

<beans>
	<bean id="triangleId" class="com.mugil.shapes.Triangle">
		<constructor-arg index="0" value="Isolseles"/>
	</bean>
</beans>

Real World Dependency Injection
spring.xml

 
<beans>
	<bean id="triangleId" class="com.mugil.shapes.Triangle">
		<property name="pointA" ref="point1"/>
		<property name="pointB" ref="point2"/>
		<property name="pointC" ref="point3"/>
	</bean>
	
	<bean id="point1" class="com.mugil.shapes.Point">
		<property name="x" value="-20"/>
		<property name="y" value="0"/>
	</bean>
	<bean id="point2" class="com.mugil.shapes.Point">
		<property name="x" value="0"/>
		<property name="y" value="0"/>
	</bean>
	<bean id="point3" class="com.mugil.shapes.Point">
		<property name="x" value="20"/>
		<property name="y" value="0"/>
	</bean>
	
</beans>

Triangle.java

 
public class Triangle {
	private String type;
	private Point pointA;
	private Point pointB;
	private Point pointC;
	
	public String getType() {
		return type;
	}

	public void setType(String type) {
		this.type = type;
	}

	public void drawShape()
	{
		System.out.println("Shape of Triangle");
	}

	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;
	}
}

Point.java

 
package com.mugil.shapes;

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;
	}
}

Shape.java

 
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;

public class Shape 
{
    public static void main(String[] args) 
    {		
	BeanFactory  objBeanFactory = new XmlBeanFactory(new FileSystemResource("spring.xml"));
	Triangle objTriangle2 =  (Triangle)objBeanFactory.getBean("triangleId");
		
	System.out.println("The Refereeed Points are = ");
	System.out.println("Point A :" + objTriangle2.getPointA().getX() +" " + objTriangle2.getPointA().getY());
	System.out.println("Point B :" + objTriangle2.getPointB().getX() +" " + objTriangle2.getPointB().getY());
	System.out.println("Point C :" + objTriangle2.getPointC().getX() +" " + objTriangle2.getPointC().getY());		
	}
}

Incase the value of the bean wont be referred else where you can define the bean property simple as below

<beans>
	<bean id="triangleId" class="com.mugil.shapes.Triangle">
		<property name="pointA">
			<bean id="point1" class="com.mugil.shapes.Point">
				<property name="x" value="-20"/>
				<property name="y" value="0"/>
			</bean>			
		</property>
		<property name="pointB" ref="point2"/>
		<property name="pointC" ref="point3"/>
	</bean>

instead of 

<beans>
	<bean id="triangleId" class="com.mugil.shapes.Triangle">
		<property name="pointA" ref="point1"/>
		<property name="pointB" ref="point2"/>
		<property name="pointC" ref="point3"/>
	</bean>
	
	<bean id="point1" class="com.mugil.shapes.Point">
		<property name="x" value="-20"/>
		<property name="y" value="0"/>
	</bean>
.
.
.

Using Alias

<bean id="triangleId" class="com.mugil.shapes.Triangle" name="triangleName">
.
.
.
</bean>
<alias name="triangleId" alias="triangle-alias"/>

In Java we can refer either by name or by alias as below
Using Alias

.
.
Triangle objTriangle2 =  (Triangle)objBeanFactory.getBean("triangleName");
(or)
Triangle objTriangle2 =  (Triangle)objBeanFactory.getBean("triangle-alias");
.
.

Using List
Triangle.java

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

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

spring.xml

<beans>
	<bean id="triangleId" class="com.mugil.shapes.Triangle" name="triangleName">
		<property name="points">
			<list>
				<ref bean="point1"/>
				<ref bean="point2"/>
				<ref bean="point3"/>
			</list>		
		</property>		
	</bean>
	<bean id="point1" class="com.mugil.shapes.Point">
			<property name="x" value="-20"/>
			<property name="y" value="0"/>
	</bean>
	<bean id="point2" class="com.mugil.shapes.Point">
		<property name="x" value="0"/>
		<property name="y" value="0"/>
	</bean>
	<bean id="point3" class="com.mugil.shapes.Point">
		<property name="x" value="20"/>
		<property name="y" value="0"/>
	</bean>
</beans>

Shape.java

List<Point> arrPoints = objTriangle2.getPoints();
		
 for (Point objPoint : arrPoints) 
 {
   System.out.println("Point :" + objPoint.getX() +" " + objPoint.getY());
 }

Autowiring
Autowiring can be done based on name as below, byType and byConstructor.

<bean id="triangleId" class="com.mugil.shapes.Triangle" name="triangleName" autowire="byName">	
</bean>
<bean id="pointA" class="com.mugil.shapes.Point">
  <property name="x" value="-20"/>
  <property name="y" value="0"/>
</bean>
<bean id="pointB" class="com.mugil.shapes.Point">
  <property name="x" value="0"/>
  <property name="y" value="0"/>
</bean>
<bean id="pointC" class="com.mugil.shapes.Point">
  <property name="x" value="20"/>
  <property name="y" value="0"/>
</bean>

The Name of the instanceVariable in class should match the autowired xml bean Name.
Triangle.java

 
public class Triangle {	
	private Point pointA;
	private Point pointB;
	private Point pointC;
.        
.
}

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