Java/Spring/IoC Init Beans

Init Interface

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

///////////////////////////////////////////////////////////////////////////////////////
//File: initInterface.xml
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
    <bean id="simpleBean1" class="SimpleBeanWithInterface" init-method="myInit">
        <property name="name">
            <value>Rob Harrop</value>
        </property>
        <property name="age">
            <value>100</value>
        </property>
    </bean>
    <bean id="simpleBean2" class="SimpleBeanWithInterface">
        <property name="age">
            <value>100</value>
        </property>
    </bean>
    <bean id="simpleBean3" class="SimpleBeanWithInterface">
        <property name="name">
            <value>Rob Harrop</value>
        </property>
    </bean>
</beans>

///////////////////////////////////////////////////////////////////////////////////////
import org.springframework.beans.factory.BeanCreationException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;
public class SimpleBeanWithInterface implements InitializingBean {
    private static final String DEFAULT_NAME = "Luke Skywalker";
    private String name = null;
    private int age = Integer.MIN_VALUE;
    public void setName(String name) {
        this.name = name;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public void myInit() {
        System.out.println("My Init");
    }
    public void afterPropertiesSet() throws Exception {
        System.out.println("Initializing bean");
        if (name == null) {
            System.out.println("Using default name");
            name = DEFAULT_NAME;
        }
        if (age == Integer.MIN_VALUE) {
            throw new IllegalArgumentException(
                    "You must set the age property of any beans of type " + SimpleBean.class);
        }
    }
    public String toString() {
        return "Name: " + name + "\nAge: " + age;
    }
    public static void main(String[] args) {
        BeanFactory factory = new XmlBeanFactory(new FileSystemResource(
                "build/initInterface.xml"));
        SimpleBeanWithInterface simpleBean1 = getBean("simpleBean1", factory);
        SimpleBeanWithInterface simpleBean2 = getBean("simpleBean2", factory);
        SimpleBeanWithInterface simpleBean3 = getBean("simpleBean3", factory);
    }
    private static SimpleBeanWithInterface getBean(String beanName,
            BeanFactory factory) {
        try {
            SimpleBeanWithInterface bean = (SimpleBeanWithInterface) factory.getBean(beanName);
            System.out.println(bean);
            return bean;
        } catch (BeanCreationException ex) {
            System.out.println("An error occured in bean configuration: "
                    + ex.getMessage());
            return null;
        }
    }
}
///////////////////////////////////////////////////////////////////////////////////////
import org.springframework.beans.factory.BeanCreationException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;
public class SimpleBean {
    private static final String DEFAULT_NAME = "Luke Skywalker";
    private String name = null;
    private int age = Integer.MIN_VALUE;
    public void setName(String name) {
        this.name = name;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public void init() {
        System.out.println("Initializing bean");
       if (name == null) {
            System.out.println("Using default name");
            name = DEFAULT_NAME;
        }
        if (age == Integer.MIN_VALUE) {
            throw new IllegalArgumentException(
                    "You must set the age property of any beans of type " + SimpleBean.class);
        }
    }
    public String toString() {
        return "Name: " + name + "\nAge: " + age;
    }
    public static void main(String[] args) {
        BeanFactory factory = new XmlBeanFactory(new FileSystemResource(
                "build/initMethod.xml"));
        SimpleBean simpleBean1 = getBean("simpleBean1", factory);        
        SimpleBean simpleBean2 = getBean("simpleBean2", factory);
        SimpleBean simpleBean3 = getBean("simpleBean3", factory);
    }
    private static SimpleBean getBean(String beanName, BeanFactory factory) {
        try {
            SimpleBean bean =(SimpleBean) factory.getBean(beanName);
            System.out.println(bean);
            return bean;
        } catch (BeanCreationException ex) {
            System.out.println("An error occured in bean configuration: "
                    + ex.getMessage());
            return null;
        }
    }
}

Lazy Init Demo

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

///////////////////////////////////////////////////////////////////////////////////////
//File: lazy.xml
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
    <bean id="destructiveBean" class="DestructiveBeanWithInterface">
        <property name="filePath">
            <value>c:/test.txt</value>
        </property>
    </bean>
    <bean id="shutdownHook" class="ShutdownHookBean" lazy-init="false"/>
</beans>

///////////////////////////////////////////////////////////////////////////////////////
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;
public class DestructiveBeanWithInterface implements InitializingBean,
        DisposableBean {
    private InputStream is = null;
    public String filePath = null;
    public void afterPropertiesSet() throws Exception {
        System.out.println("Initializing Bean");
        if (filePath == null) {
            throw new IllegalArgumentException(
                    "You must specify the filePath property of " + DestructiveBean.class);
        }
        is = new FileInputStream(filePath);
    }
    public void destroy() {
        System.out.println("Destroying Bean");
        if (is != null) {
            try {
                is.close();
                is = null;
            } catch (IOException ex) {
                System.err.println("WARN: An IOException occured"
                        + " trying to close the InputStream");
            }
        }
    }
    public void setFilePath(String filePath) {
        this.filePath = filePath;
    }
}

///////////////////////////////////////////////////////////////////////////////////////
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
public class ShutdownHookBean implements BeanFactoryAware,
        Runnable {
    private ConfigurableListableBeanFactory factory;
    public void setBeanFactory(BeanFactory factory) throws BeansException {
        if (factory instanceof ConfigurableListableBeanFactory) {
            this.factory = (ConfigurableListableBeanFactory) factory;
            Runtime.getRuntime().addShutdownHook(new Thread(this));
        }
    }
    public void run() {
        if (factory != null) {
            System.out.println("Destroying Singletons");
            factory.destroySingletons();
            System.out.println("Singletons Destroyed");
        }
    }
}
///////////////////////////////////////////////////////////////////////////////////////
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;
public class DestructiveBean implements InitializingBean {
    private InputStream is = null;
    public String filePath = null;
    public void afterPropertiesSet() throws Exception {
        System.out.println("Initializing Bean");
        if (filePath == null) {
            throw new IllegalArgumentException(
                    "You must specify the filePath property of " + DestructiveBean.class);
        }
        is = new FileInputStream(filePath);
    }
    public void destroy() {
        System.out.println("Destroying Bean");
        if (is != null) {
            try {
                is.close();
                is = null;
            } catch (IOException ex) {
                System.err.println("WARN: An IOException occured"
                        + " trying to close the InputStream");
            }
        }
    }
    public void setFilePath(String filePath) {
        this.filePath = filePath;
    }
}
///////////////////////////////////////////////////////////////////////////////////////
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
public class LazyInitDemo {
    public static void main(String[] args) {
        ApplicationContext ctx = new FileSystemXmlApplicationContext(
                "build/lazy.xml");
        DestructiveBeanWithInterface bean = (DestructiveBeanWithInterface) ctx
                .getBean("destructiveBean");
    }
}

SimpleBean Init Method

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

///////////////////////////////////////////////////////////////////////////////////////
//File: initMethod.xml
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
    <bean id="simpleBean1" class="SimpleBean" init-method="init">
        <property name="name">
            <value>Joe Wang</value>
        </property>
        <property name="age">
            <value>100</value>
        </property>
    </bean>
    <bean id="simpleBean2" class="SimpleBean" init-method="init">
        <property name="age">
            <value>100</value>
        </property>
    </bean>
    <bean id="simpleBean3" class="SimpleBean" init-method="init">
        <property name="name">
            <value>Joe Wang</value>
        </property>
    </bean>
</beans>
///////////////////////////////////////////////////////////////////////////////////////
import org.springframework.beans.factory.BeanCreationException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;
public class SimpleBean {
    private static final String DEFAULT_NAME = "Luke Skywalker";
    private String name = null;
    private int age = Integer.MIN_VALUE;
    public void setName(String name) {
        this.name = name;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public void init() {
        System.out.println("Initializing bean");
       if (name == null) {
            System.out.println("Using default name");
            name = DEFAULT_NAME;
        }
        if (age == Integer.MIN_VALUE) {
            throw new IllegalArgumentException(
                    "You must set the age property of any beans of type " + SimpleBean.class);
        }
    }
    public String toString() {
        return "Name: " + name + "\nAge: " + age;
    }
    public static void main(String[] args) {
        BeanFactory factory = new XmlBeanFactory(new FileSystemResource(
                "build/initMethod.xml"));
        SimpleBean simpleBean1 = getBean("simpleBean1", factory);        
        SimpleBean simpleBean2 = getBean("simpleBean2", factory);
        SimpleBean simpleBean3 = getBean("simpleBean3", factory);
    }
    private static SimpleBean getBean(String beanName, BeanFactory factory) {
        try {
            SimpleBean bean =(SimpleBean) factory.getBean(beanName);
            System.out.println(bean);
            return bean;
        } catch (BeanCreationException ex) {
            System.out.println("An error occured in bean configuration: "
                    + ex.getMessage());
            return null;
        }
    }
}