Simple spEL using Annotation

 
 
 
 
 
 
 
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Just like JavaConfig being an alternate way to provide configuration metadata instead of xml files, Annotations can be used in place of xml metadata in spEL as well.

 

Step 1 : Create the POJOs, Candidate.java and Address.java

 
File : Candidate.java
 


package com.simpleCodeStuffs.spEL;

import org.springframework.beans.factory.annotation.Value;

import org.springframework.stereotype.Component;

@Component("elCandidate")
public class Candidate {

	@Value("Poorni")
	private String name;

	@Value("27")
	private int age;

	@Value("#{elAddress}")
	private Address addrs;

	@Value("#{elAddress.area}")
	private String area;

	public String getArea() {
		return area;
	}

	public void setArea(String area) {
		this.area = area;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public Address getAddrs() {
		return addrs;
	}

	public void setAddrs(Address addrs) {
		this.addrs = addrs;
	}

}

 

File : Address.java
 


package com.simpleCodeStuffs.spEL;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("elAddress")
public class Address {

	@Value("22/7")
	private String doorNo;

	@Value("MKM Street")
	private String street;

	@Value("Ambattur")
	private String area;

	public String getArea() {
		return area;
	}

	public void setArea(String area) {
		this.area = area;
	}

	public String getDoorNo() {
		return doorNo;
	}

	public void setDoorNo(String doorNo) {
		this.doorNo = doorNo;
	}

	public String getStreet() {
		return street;
	}

	public void setStreet(String street) {
		this.street = street;
	}
}

 

Step 2 : Enable auto component scanning in the xml file

 

File : elBeans.xml

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
	http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
	http://www.springframework.org/schema/context
	http://www.springframework.org/schema/context/spring-context-3.0.xsd">
	<context:component-scan base-package="com.simpleCodeStuffs.spEL" />


</beans>

 

Step 3 : Main class

 

File : MainClass.java


package com.simpleCodeStuffs.spEL;

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

public class MainClass {

	public static void main(String[] args) {

		ApplicationContext context = 
			      new ClassPathXmlApplicationContext("elBeans.xml");
		Candidate can = (Candidate) context.getBean("elCandidate");
		Address add = (Address) context.getBean("elAddress");

		System.out.println("Name  : " + can.getName());
		System.out.println("Age  : " + can.getAge());
		System.out.println("Area  : " + can.getArea());
		System.out.println("Address : " + can.getAddrs().getDoorNo());
		System.out.println("t " + add.getStreet());
		System.out.println("t  " + add.getArea());
	}

}

 

Step 4 :

 
Run the MainClass. The output is as follows
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spelAnnotationOutput
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Note that these are the values injected into the bean, through annotation.

 

Step 5 :

Make modification in the elBeans.xml
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Values injected from xml overrides the values from annotation[/box]
 

The bean ‘elCandidate’ is defined. The value for the property ‘€˜age’€™ is left out here.

 

File : elBeans.xml
 

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
	http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
	http://www.springframework.org/schema/context
	http://www.springframework.org/schema/context/spring-context-3.0.xsd">
	<context:component-scan base-package="com.simpleCodeStuffs.spEL" />
	
 	
 <bean id="elCandidate" class="com.simpleCodeStuffs.spEL.Candidate">
		<property name="name" value="Sandy" />
	
		<property name="addrs" value="#{elAddress}" />
			<property name="area" value="#{elAddress.area}" />
	</bean>
</beans>

 

Now, run the program again. The output is

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spelAnnotationOutputModified
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Note that, the value for the attribute ‘name’€™ provided through xml(Sandy) overrides the one provided through annotation(Poorni). The other values are taken from annotation as they have not been injected from xml.

 
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