AddInstanceToContext,java

package harschware.sandbox.scratch;

import org.springframework.beans.factory.FactoryBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.Arrays;
import java.util.Objects;

/**
 * Demonstrates wrapping a java object as a Spring bean
 */
public class AddInstanceToContext {

    private static Car theCar = new Car("chevy");

    /**
     * Main entry point into program
     *
     * @param args: list of args
     */
    public static void main(String[] args) {
        ApplicationContext ctx = createSpringContext(theCar);

        System.out.println(Arrays.asList(ctx.getBeanDefinitionNames()));

        SwappableBeans.Person personFromXml = (SwappableBeans.Person) ctx.getBean("personFromXml");
        System.out.println("Person = " + personFromXml);

        Car chevy = (Car) ctx.getBean("carFromXml");
        System.out.println("Car = " + chevy);
        System.out.println("Are the cars equal? " + theCar.equals(chevy));

        theCar.setType("Toyota");
        System.out.println("Was type changed? " + chevy);

    }

    public static ApplicationContext createSpringContext(final Car car) {
        CarHolder carHolder = new CarHolder(car);

        ApplicationContext context = new ClassPathXmlApplicationContext("scratch/applicationContext-addBean.xml");
        return context;
    } // end static method

    public static class Car {
        String type;

        public Car(String type) {
            this.type = type;
        }

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

        @Override
        public String toString() {
            final StringBuilder sb = new StringBuilder("Car{");
            sb.append("type='").append(type).append('\'');
            sb.append('}');
            return sb.toString();
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            Car car = (Car) o;
            return Objects.equals(type, car.type);
        }

        @Override
        public int hashCode() {
            return Objects.hash(type);
        }
    } // end class


    public static class CarFactory implements FactoryBean<Car> {

        @Override
        public Car getObject() throws Exception {
            return CarHolder.getCar();
        }

        @Override
        public Class<?> getObjectType() {
            return Car.class;
        }

        @Override
        public boolean isSingleton() {
            return true;
        }

    } // end class

    public static class CarHolder {
        static Car car;

        public CarHolder(Car ctx) {
            this.car = ctx;
        }

        public static Car getCar() {
            if (car == null) {
                throw new IllegalStateException("CarHolder not initialized");
            }
            return car;
        }
    } // end class

} // end class

applicationContext-addBean.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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

    <!--https://stackoverflow.com/questions/12800769/replace-spring-bean-in-one-context-with-mock-version-from-another-context-->
    <bean id="personFromXml" class="harschware.sandbox.scratch.SwappableBeans.Person">
        <constructor-arg index="0" value="Tim"/>
        <constructor-arg index="1" type="java.lang.Integer" value="46"/>
    </bean>

    <bean id="carFromXml" class="harschware.sandbox.scratch.AddInstanceToContext$CarFactory" />
</beans>