Spring Annotation using @Resource

In the previous 2 articles, we have explored about Spring annotation that how it helps to reduce the complex XML configuration to simply annotating component classes to take it effects. With @Autowired<link> example we have seen it works similar to ‘byType’ autowiring mode and with @Qualifier example we solved the ambiguity problems when we got two beans registered with same data type

So question arises here, does Spring support ‘byName’ autowiring mode similar to byType with @Autowired annotation? Yes, with @Resource you can do it

Let’s see detailed example based on this annotation @Resource

Technology Used

  • Java 1.7
  • Eclipse Kepler IDE
  • Maven 3.0.4
  • Spring-4.0.0-RELEASE

Mavenize or download required jars

Add Spring-4.0.0 dependencies to the pom.xml

<dependency>
	<groupId>org.springframework</groupId>
	<artifactId>spring-core</artifactId>
	<version>${spring.version}</version>
</dependency>
<dependency>
	<groupId>org.springframework</groupId>
	<artifactId>spring-context</artifactId>
	<version>${spring.version}</version>
</dependency>

Folks who aren’t familiar with Maven concepts or don’t require maven for their project, can download the below jars individually from the spring site and include them in the classpath

  • spring-core-4.0.0-RELEASE
  • spring-context-4.0.0-RELEASE
  • spring-beans-4.0.0-RELEASE
  • spring-aop-4.0.0-RELEASE
  • spring-expression-4.0.0-RELEASE
  • commons-logging-1.1.1
  • aopalliance-1.0

Let’s see coding in action

 

Create simple Spring bean for Employee & Addess

Address class

Four simple properties with their setter/getter

Address.java

package com.spring.series.annotation;

public class Address {

	private String street;
	private String city;
	private String state;
	private String zipcode;

	/**
	 * getter's and setter's
	 */
	public String getStreet() {
		return street;
	}
	public void setStreet(String street) {
		this.street = street;
	}
	public String getCity() {
		return city;
	}
	public void setCity(String city) {
		this.city = city;
	}
	public String getState() {
		return state;
	}
	public void setState(String state) {
		this.state = state;
	}
	public String getZipcode() {
		return zipcode;
	}
	public void setZipcode(String zipcode) {
		this.zipcode = zipcode;
	}

	/**
	 * This method prints the address details
	 */
	public void printAddressDetail(){
		System.out.println("Address Street \t\t: " + street);
		System.out.println("Address City \t\t: " + city);
		System.out.println("Address State \t\t: " + state);
		System.out.println("Address Zip Code \t: " + zipcode);
	}
}

Employee class

Four simple properties and its setter/getter & one complex property named Address annotated with @Resource and in the parenthesis, we have informed the spring container which bean needs to injected into address property with ‘name’ attribute.

See the annotation above this line “private Address address;”

Employee.java

package com.spring.series.annotation;

import javax.annotation.Resource;

public class Employee {

	private String name;
	private int age;
	private String employeeCode;
	private String designation;

	// property address autowired using annotation
	@Resource(name="addressB")
	private Address address;

	/**
	 * getter's and setter's
	 */
	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 String getEmployeeCode() {
		return employeeCode;
	}
	public void setEmployeeCode(String employeeCode) {
		this.employeeCode = employeeCode;
	}
	public String getDesignation() {
		return designation;
	}
	public void setDesignation(String designation) {
		this.designation = designation;
	}
	public Address getAddress() {
		return address;
	}
	public void setAddress(Address address) {
		this.address = address;
	}

	/**
	 * This method prints the employee details
	 */
	public void printEmployeeDetail(){

		System.out.println("Employee Name \t\t: " + name);
		System.out.println("Employee Age \t\t: " + age);
		System.out.println("Employee Code \t\t: " + employeeCode);
		System.out.println("Employee Designation \t: " + designation);

		System.out.println("\nAutowired Address object & Printing Address details\n");

		// this loc invokes method of Address class & this object is injected during spring bean instantiation
		address.printAddressDetail();
	}
}

Create Spring Bean Configuration file (Spring XML)

Two simple beans employee & address are defined in the Spring configuration file with no explicit relationship between them because dependent address bean gets injected into the employee via @Resource(name=”exactBeanName”) annotation declared in the component class (i.e.; Employee.java)

SpringContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<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.xsd
	http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">

	<context:annotation-config />

	<!-- employee bean definition goes here -->
	<bean id="employee" class="com.spring.series.annotation.Employee">
		<property name="name" value="Mark" />
		<property name="age" value="32" />
		<property name="employeeCode" value="E10910" />
		<property name="designation" value="Software Architect" />
	</bean>

	<!-- address bean definition goes here -->
	<bean id="addressA" class="com.spring.series.annotation.Address">
		<property name="street" value="Spring Office St." />
		<property name="city" value="Columbus" />
		<property name="state" value="OHIO" />
		<property name="zipcode" value="43211" />
	</bean>

	<!-- address bean definition goes here -->
	<bean id="addressB" class="com.spring.series.annotation.Address">
		<property name="street" value="Spring Office St. B" />
		<property name="city" value="Columbus B" />
		<property name="state" value="OHIO B" />
		<property name="zipcode" value="43211 B" />
	</bean>

</beans>

Note: Name of the Spring Bean Configuration file can be anything (not necessary to have SpringContext.xml) and it’s your choice. But, in the enterprise application keep these file names appropriate to the business context. So that it will increase the readability of the application.

Project Structure in Eclipse (Package Explorer view)

SpringAnnotationResource

Test the Application that’s exactly …. Run it!

Let’s test using ApplicationContext

Simple test class – self descriptive

TestEmployee.java

package com.spring.series.annotation;

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

public class TestEmployee {

	public static void main(String[] args) {
		testAnnotation();
	}

	private static void testAnnotation(){

		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("com/spring/series/annotation/SpringContext.xml");
		Employee employee = (Employee) applicationContext.getBean("employee");

		System.out.println("\nSpring Annoatation with @Resource \n");

		// invoke print() method of Employee class
		employee.printEmployeeDetail();
	}
}

Output in console

Spring Annoatation with @Resource 

Employee Name 		: Mark
Employee Age 		: 32
Employee Code 		: E10910
Employee Designation 	: Software Architect

Autowired Address object & Printing Address details

Address Street 		: Spring Office St. B
Address City 		: Columbus B
Address State 		: OHIO B
Address Zip Code 	: 43211 B

In the next article, we will implement an example based on @Required annotation which enforces to inject properties into bean otherwise throwing error

Download project

Spring Annotation using @Resource (3kB)

Happy Coding !!
Happy Learning !!