Java/Spring/IoC Singleton

Achieving Singleton in IoC

/*
Pro Spring
By Rob Harrop
Jan Machacek
ISBN: 1-59059-461-4
Publisher: Apress
*/

///////////////////////////////////////////////////////////////////////////////////////
//File: beans.xml
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
    
    <!-- non-singleton examples -->
    <bean id="nonSingleton" class="java.lang.String" singleton="true">
        <constructor-arg>
            <value>Value</value>
        </constructor-arg>
    </bean>
</beans>

///////////////////////////////////////////////////////////////////////////////////////
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;
public class NonSingleton {
    public static void main(String[] args) {
        BeanFactory factory = new XmlBeanFactory(new FileSystemResource(
                "build/beans.xml"));
        
        String s1 = (String)factory.getBean("nonSingleton");
        String s2 = (String)factory.getBean("nonSingleton");
        
        System.out.println("Identity Equal?: " + (s1 ==s2));
        System.out.println("Value Equal:? " + s1.equals(s2));
        System.out.println(s1);
        System.out.println(s2);
    }
}

Non Singleton

/*
Pro Spring
By Rob Harrop
Jan Machacek
ISBN: 1-59059-461-4
Publisher: Apress
*/

///////////////////////////////////////////////////////////////////////////////////////
//File: beans.xml
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
    
    <!-- non-singleton examples -->
    <bean id="nonSingleton" class="java.lang.String" singleton="false">
        <constructor-arg>
            <value>Value</value>
        </constructor-arg>
    </bean>
</beans>

///////////////////////////////////////////////////////////////////////////////////////
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;
public class NonSingleton {
    public static void main(String[] args) {
        BeanFactory factory = new XmlBeanFactory(new FileSystemResource(
                "build/beans.xml"));
        
        String s1 = (String)factory.getBean("nonSingleton");
        String s2 = (String)factory.getBean("nonSingleton");
        
        System.out.println("Identity Equal?: " + (s1 ==s2));
        System.out.println("Value Equal:? " + s1.equals(s2));
        System.out.println(s1);
        System.out.println(s2);
    }
}