Some help required for understanding spring lifecycle

[Rahul Shivsharan]

my LifeCycleBean.java file as follows,

package com.jal;
import org.springframework.beans.factory.BeanNameAware;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.InitializingBean; 
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.BeanFactory;

public class LifeCycleBean implements BeanNameAware,BeanFactoryAware,BeanPostProcessor,InitializingBean,DisposableBean{
	
	private String studentName;
	
	public LifeCycleBean(){
		System.out.println("1> LifeCycleBean is initialised.... ");
	}
	
	@Override
	public void setBeanName(String name){
		System.out.println("3> set Bean Name "+name);
	}
	
	@Override
	public void setBeanFactory(BeanFactory beanFactory){
		System.out.println("4> Set Bean Factory ");
	}

	@Override
	public Object postProcessAfterInitialization(Object bean, String beanName){
		System.out.println("7> Post process after initialisation ");
		return null;
	}

	@Override	
	public Object postProcessBeforeInitialization(Object bean, String beanName){
		System.out.println("5> Post process before initialisation ");	
		return null;
	} 
 	
	@Override
	public void afterPropertiesSet(){
		System.out.println("6> After properties set ");
	} 
 
	@Override
	public void destroy(){
		System.out.println("9> Bean is being Destroyed ");	
	}
	
	public void setStudentName(String studentName){
		System.out.println("2> in setter of StudentName ");
		this.studentName = studentName;
	}
	
	public String getStudentName(){
		return this.studentName;
	}
 
} 

my bean-cfg.xml file as follows,

<?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">
		<bean id="contractEmp" class="com.impl.ContractEmpl" />
		<bean id="permanentEmp" class="com.impl.PermanentEmpl" />
		<bean id="logBean" class="com.jal.LoggerChk" />
		<bean id="dms" class="com.jal.ConnectionDMS" />
		
		<bean id="emplServiceObj" class="com.service.EmployeeService">
			<property name="emp" ref="contractEmp" />
		</bean>					
		
		<bean id="init-pojo" class="com.jal.LifeCycleBean">
			<property name="studentName" value="David Serverkartha Sankulichit" />
		</bean>
</beans>							

my MainPractise02.java file were main method is present , is as follows,

package com.main;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.beans.factory.BeanFactory; 
import com.jal.LifeCycleBean;
public class MainPractise02{
	public static void main(String [] args){
		BeanFactory beanFactory = null;
		LifeCycleBean myObj = null;
		try{
			beanFactory = new ClassPathXmlApplicationContext("bean-cfg.xml");
			myObj = (LifeCycleBean) beanFactory.getBean("init-pojo");
			System.out.println(" ----> "+myObj.getStudentName());
		}catch(Exception e){
			System.out.println(e);
		}
	}
}

now the ouput on command prompt as follows,

D:\Rahul S Shivsharan\Practise\Spring Project>ant run -DclassnameParam=com.main.MainPractise02
Buildfile: D:\Rahul S Shivsharan\Practise\Spring Project\build.xml

run:
     [java] Aug 23, 2011 7:22:52 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh
     [java] INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1ab5d6d: startup date [Tue Aug 23 19:22:52 IST 2011]; root of context hierarchy
     [java] Aug 23, 2011 7:22:52 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
     [java] INFO: Loading XML bean definitions from class path resource [bean-cfg.xml]
     [java] 1> LifeCycleBean is initialised....
     [java] 2> in setter of StudentName
     [java] 3> set Bean Name init-pojo
     [java] 4> Set Bean Factory
     [java] 6> After properties set
     [java] Aug 23, 2011 7:22:53 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
     [java] INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@67564: defining beans [contractEmp,permanentEmp,logBean,dms,emplServiceObj,init-p
ojo]; root of factory hierarchy
     [java]  ContractEmpl initialised
     [java] 5> Post process before initialisation
     [java]  PermanentEmpl initialised
     [java] 5> Post process before initialisation
     [java]  LoggerChk initialised...
     [java] 5> Post process before initialisation
     [java]  ConnectionDMS initialised...
     [java] 5> Post process before initialisation
     [java]  EmployeeService initialised...
     [java]  in setter of Empoyee...
     [java] 5> Post process before initialisation
     [java]  ----> David Serverkartha Sankulichit
     [echo] Java running completed

BUILD SUCCESSFUL
Total time: 1 second

D:\Rahul S Shivsharan\Practise\Spring Project>

my questions are,

why method postProcessBeforeInitialization() is called everytime whenever other beans declared in bean-cfg.xml are initialised ?,
why methods postProcessAfterInitialization() and destroy() were not called ?

wiating for your reply

[Mark Spritzler]

1) You are using BeanFactory instead of your instance variable being ApplicationContext, probably why the post of the BeanPostProcessor doesn't get called.

2) a BeanPostProcessor will always receive every bean declared in your configuration because that is what BeanPostProcessors are about, they post process all your beans. Basically they get passed the entire Map of beans and loops through them all to see if they need to do something to that bean.

Mark

[Rahul Shivsharan]

i didn't understood the first point,

Are you saying that as i'm using BeanFactory thats the reason postProcessesAfterinitialisation() and destroy() methods are not getting called ?

Can you explain me , please

[Mark Spritzler]

Rahul Shivsharan wrote:i didn't understood the first point,

Are you saying that as i'm using BeanFactory thats the reason postProcessesAfterinitialisation() and destroy() methods are not getting called ?

Can you explain me , please

The BeanFactory is the older way to use Spring, it used to be the Spring Container that was used. Then Spring introduced the ApplicationContext, which added new features including more steps into the Initialization Phase, which is what you are looking at. The BeanPostProcessor step was not part of the BeanFactory initialization lifecycle. But it is with ApplicationContext. ApplicationContext is a Bean Factory plus more.

The destroy method only gets called when you call close() on the ApplicationContext, and that method is only on the ConfigurableApplicationContext interface, so you would have to cast your ApplicationContext to that type, then call close().

Mark

[Rahul Shivsharan]

I changed the code as you said but still it gives a nullpointer exception,

I did the changes in file MainPractise04.java ,

package com.main;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.context.ApplicationContext;
import com.inter.Performer; 


public class MainPractise04{
	public static void main(String [] args){
		ApplicationContext applicationContext = null;
		Performer myObj = null;
		//beanFactory = new ClassPathXmlApplicationContext("bean-prac-cfg.xml");
		applicationContext = new ClassPathXmlApplicationContext("bean-cfg.xml");
		myObj = (Performer) applicationContext.getBean("jgl-pojo");			
		myObj.perform();		
	}
}

and the command prompt shows

D:\Rahul S Shivsharan\Practise\Spring Project>ant run -DclassnameParam=com.main.MainPractise04
Buildfile: D:\Rahul S Shivsharan\Practise\Spring Project\build.xml

run:
     [java] Aug 25, 2011 11:23:06 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh
     [java] INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@ad8bfd: startup date [Thu Aug 25 11:23:06 IST
     [java] Aug 25, 2011 11:23:06 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
     [java] INFO: Loading XML bean definitions from class path resource [bean-cfg.xml]
     [java] 1> LifeCycleBean is initialised....
     [java] 2> in setter of StudentName
     [java] 3> set Bean Name init-pojo
     [java] 4> Set Bean Factory
     [java] 6> After properties set
     [java] Aug 25, 2011 11:23:06 AM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
     [java] INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@6afc53: defining beans
pojo,jgl-pojo]; root of factory hierarchy
     [java]  ContractEmpl initialised
     [java] 5> Post process before initialisation
     [java]  PermanentEmpl initialised
     [java] 5> Post process before initialisation
     [java]  LoggerChk initialised...
     [java] 5> Post process before initialisation
     [java]  ConnectionDMS initialised...
     [java] 5> Post process before initialisation
     [java]  EmployeeService initialised...
     [java]  in setter of Empoyee...
     [java] 5> Post process before initialisation
     [java] 2> JUGGLER INSTATIATED....
     [java] 5> Post process before initialisation
     [java] java.lang.NullPointerException
     [java]     at org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:194)
     [java]     at org.apache.tools.ant.taskdefs.Java.run(Java.java:771)
     [java]     at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:221)
     [java]     at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:135)
     [java]     at org.apache.tools.ant.taskdefs.Java.execute(Java.java:108)
     [java]     at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
     [java]     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     [java]     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
     [java]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
     [java]     at java.lang.reflect.Method.invoke(Method.java:601)
     [java]     at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
     [java]     at org.apache.tools.ant.Task.perform(Task.java:348)
     [java]     at org.apache.tools.ant.Target.execute(Target.java:390)
     [java]     at org.apache.tools.ant.Target.performTasks(Target.java:411)
     [java]     at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
     [java]     at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
     [java]     at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
     [java]     at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
     [java]     at org.apache.tools.ant.Main.runBuild(Main.java:809)
     [java]     at org.apache.tools.ant.Main.startAnt(Main.java:217)
     [java]     at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280)
     [java]     at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109)
     [java] Caused by: java.lang.NullPointerException
     [java]     at com.main.MainPractise04.main(Unknown Source)
     [java]     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     [java]     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
     [java]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
     [java]     at java.lang.reflect.Method.invoke(Method.java:601)
     [java]     at org.apache.tools.ant.taskdefs.ExecuteJava.run(ExecuteJava.java:217)
     [java]     at org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:152)
     [java]     ... 21 more
     [java] Java Result: -1
     [echo] Java running completed

BUILD SUCCESSFUL
Total time: 1 second

D:\Rahul S Shivsharan\Practise\Spring Project>

as you can see the class Juggler.java is initialised, its sop in constructor is printed, so why spring container is not able to call the method perform(),
it throws nullpointer exception

[Rahul Shivsharan]

i removed the try catch and did changes as you said,

my changed file MainPractise04.java,

package com.main;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.context.ApplicationContext;
import com.inter.Performer; 


public class MainPractise04{
	public static void main(String [] args){
		ApplicationContext applicationContext = null;
		Performer myObj = null;
		//beanFactory = new ClassPathXmlApplicationContext("bean-prac-cfg.xml");
		applicationContext = new ClassPathXmlApplicationContext("bean-cfg.xml");
		myObj = (Performer) applicationContext.getBean("jgl-pojo");			
		myObj.perform();		
	}
}

but still it gives an exception as nullpointer

D:\Rahul S Shivsharan\Practise\Spring Project>ant run -DclassnameParam=com.main.MainPractise04
Buildfile: D:\Rahul S Shivsharan\Practise\Spring Project\build.xml

run:
     [java] Aug 25, 2011 11:23:06 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh
     [java] INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@ad8bfd: startup date [Thu Aug 25 11:23:06 IST 2011]; root
     [java] Aug 25, 2011 11:23:06 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
     [java] INFO: Loading XML bean definitions from class path resource [bean-cfg.xml]
     [java] 1> LifeCycleBean is initialised....
     [java] 2> in setter of StudentName
     [java] 3> set Bean Name init-pojo
     [java] 4> Set Bean Factory
     [java] 6> After properties set
     [java] Aug 25, 2011 11:23:06 AM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
     [java] INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@6afc53: defining beans [contractEm
pojo,jgl-pojo]; root of factory hierarchy
     [java]  ContractEmpl initialised
     [java] 5> Post process before initialisation
     [java]  PermanentEmpl initialised
     [java] 5> Post process before initialisation
     [java]  LoggerChk initialised...
     [java] 5> Post process before initialisation
     [java]  ConnectionDMS initialised...
     [java] 5> Post process before initialisation
     [java]  EmployeeService initialised...
     [java]  in setter of Empoyee...
     [java] 5> Post process before initialisation
     [java] 2> JUGGLER INSTATIATED....
     [java] 5> Post process before initialisation
     [java] java.lang.NullPointerException
     [java]     at org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:194)
     [java]     at org.apache.tools.ant.taskdefs.Java.run(Java.java:771)
     [java]     at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:221)
     [java]     at org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:135)
     [java]     at org.apache.tools.ant.taskdefs.Java.execute(Java.java:108)
     [java]     at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
     [java]     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     [java]     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
     [java]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
     [java]     at java.lang.reflect.Method.invoke(Method.java:601)
     [java]     at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
     [java]     at org.apache.tools.ant.Task.perform(Task.java:348)
     [java]     at org.apache.tools.ant.Target.execute(Target.java:390)
     [java]     at org.apache.tools.ant.Target.performTasks(Target.java:411)
     [java]     at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
     [java]     at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
     [java]     at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
     [java]     at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
     [java]     at org.apache.tools.ant.Main.runBuild(Main.java:809)
     [java]     at org.apache.tools.ant.Main.startAnt(Main.java:217)
     [java]     at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280)
     [java]     at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109)
     [java] Caused by: java.lang.NullPointerException
     [java]     at com.main.MainPractise04.main(Unknown Source)
     [java]     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     [java]     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
     [java]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
     [java]     at java.lang.reflect.Method.invoke(Method.java:601)
     [java]     at org.apache.tools.ant.taskdefs.ExecuteJava.run(ExecuteJava.java:217)
     [java]     at org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:152)
     [java]     ... 21 more
     [java] Java Result: -1
     [echo] Java running completed

BUILD SUCCESSFUL
Total time: 1 second

D:\Rahul S Shivsharan\Practise\Spring Project>

you can see, the bean Juggler is getting initialised the sop is printed,
so than why spring container is not able to invoke method perform() ?

[Mark Spritzler]

Sorry, looking at your code again.

@Override  
    public Object postProcessAfterInitialization(Object bean, String beanName){  
        System.out.println("7> Post process after initialisation ");  
        return null;  
    }  
  
    @Override     
    public Object postProcessBeforeInitialization(Object bean, String beanName){  
        System.out.println("5> Post process before initialisation ");      
        return null;  
    }   

I would have both those methods return bean and not null. So you basically nulled it out yourself.

So instead use

@Override  
    public Object postProcessAfterInitialization(Object bean, String beanName){  
        System.out.println("7> Post process after initialisation ");  
        return bean;  
    }  
  
    @Override     
    public Object postProcessBeforeInitialization(Object bean, String beanName){  
        System.out.println("5> Post process before initialisation ");      
        return bean;  
    }   

Also, get rid of those first two lines in your main method. You don't need to have

ApplicationContext context = null;

Just combine it with your instantiation of those two objects.

so just

public class MainPractise04{  
    public static void main(String [] args){   
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("bean-cfg.xml");  
        Performer myObj = (Performer) applicationContext.getBean("jgl-pojo");           
        myObj.perform();          
    }  
}

Mark