A simple application to demonstrate how to use Java based configuration in Spring Framework without using XML based configuration.
The following steps / classes are taken for this simple application to work.
1. A simple POJO bean as Address
2. A simple POJO bean as Employee having being injected by Address object.
3. Java Based Configuration class replacing Spring Configuration XML.
4. A simple Spring xml file having components scan tag
5. Test class for running the example
Note : To run above example application classpath must include all Spring Jars and CGLIB jar [cglib-nodep-x.x.x.jar]
Output of the program :
The following steps / classes are taken for this simple application to work.
1. A simple POJO bean as Address
package com.hubberspot.spring.configuration;
public class Address {
private String street;
private String city;
private String state;
public Address() {
}
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 void initialize() {
System.out.println("Initialization of Address ... ");
}
public void destroy() {
System.out.println("Destruction of Address ... ");
}
}
2. A simple POJO bean as Employee having being injected by Address object.
package com.hubberspot.spring.configuration;
import javax.inject.Inject;
// Create a POJO class Employee which has a
// Address Object reference as instance variable
public class Employee {
private String name;
private int age;
@Inject
private Address address;
public Employee() {
}
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 getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public void init() {
System.out.println("Initialization of Employee ... ");
}
public void clean() {
System.out.println("Destruction of Employee ... ");
}
}
3. Java Based Configuration class replacing Spring Configuration XML.
package com.hubberspot.spring.configuration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
// @Configuration makes this Java class as configuration
// for the Spring Framework. It declares two beans here
// instead of providing it in spring configuration file
// we can provide it in Java class
@Configuration
public class EmployeeConfiguration {
// @Bean registers Address as a Spring bean
@Bean(initMethod="initialize", destroyMethod= "destroy")
public Address address() {
Address address = new Address();
address.setStreet("Town Hall Street");
address.setCity("Pune");
address.setState("Maharashtra");
return address;
}
// @Bean registers Employee as a Spring bean
@Bean(initMethod="init", destroyMethod= "clean")
public Employee employee() {
Employee employee = new Employee();
employee.setName("Jonty");
employee.setAge(28);
employee.setAddress(address());
return employee;
}
}
4. A simple Spring xml file having components scan tag
|
5. Test class for running the example
package com.hubberspot.spring.configuration;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Test {
public static void main(String[] args) {
// ApplicationContext is a Spring interface which
// provides with the configuration for an application.
// It provides us with all the methods that BeanFactory
// provides. It loads the file resources in a older
// and generic manner. It helps us to publish events to the
// listener registered to it. It also provides quick support
// for internationalization. It provides us with the object
// requested, it reads the configuration file and provides
// us with the necessary object required.
// Since we are using Java based configuration method so instead
// of using concrete implementation of ApplicationContext
// which is ClassPathXmlApplicationContext we are using
// AnnotationConfigApplicationContext to load and register
// annotated configuration classes. Instead of xml we provide
// name of the java configuration Class object (instance of this Class)
AbstractApplicationContext context =
new AnnotationConfigApplicationContext(EmployeeConfiguration.class);
context.registerShutdownHook();
// In order to get a object instantiated for a particular bean
// we call getBean() method of ClassPathXmlApplicationContext
// passing it the id for which the object is to be needed.
// Here getBean() returns an Object. We need to cast it back
// to the Employee object. Without implementing new keyword we
// have injected object of Employee just by reading an xml
// configuration file.
Employee employee = (Employee)context.getBean("employee");
if(employee.getAddress()==null){
System.out.println("The Employee Name : " + employee.getName());
System.out.println("The Employee Age : " + employee.getAge());
System.out.println("The Employee Address : " + "is not provided");
}
else{
System.out.println("The Employee Name : " + employee.getName());
System.out.println("The Employee Age : " + employee.getAge());
System.out.println("The Employee Address : " +
employee.getAddress().getStreet() + " " +
employee.getAddress().getCity() + " " +
employee.getAddress().getState());
}
}
}
Note : To run above example application classpath must include all Spring Jars and CGLIB jar [cglib-nodep-x.x.x.jar]
Output of the program :