Download Spring(bean life cycle management) and more Study notes Applications of Computer Sciences in PDF only on Docsity!
07 - Spring Bean Life Cycle
TOC
- 06 - Spring Bean Scopes
- 08 - Spring BeanPost Processors
7.1 Overview of Spring Bean Life Cycle
Life of traditional java objects starts on calling new operator which instantiates the object
and finalize() method is getting called when the object is eligible for garbage collection.
Life cycle of Spring beans are different as compared to traditional java objects.
Spring framework provides the following ways which can be used to control the lifecycle
of bean:
1. InitializingBean and DisposableBean callback interfaces
2. Bean Name, bean factory and Application Context Aware interfaces for specific
behavior
3. custom init() and destroy() methods in bean configuration file
For annotation based configurations -
@PostConstruct and @PreDestroy annotations
Below diagram shows the complete lifecycle methods (from instantiate to Ready To use
Following diagram shows the method calling at the time of destruction.
7.2 InitializingBean and DisposbleBean callback interfaces
@Override public void destroy() throws Exception { System.out.println("destroy method of person bean is called !! "); } @Override
public void afterPropertiesSet() throws Exception { called !! ");System.out.println("afterPropertiesSet method^ of^ person^ bean is } public String getName() { return name; } public void setName(String name) { this.name = name; } }
b) Create a beans.xml file in src directory to define the PersonBean
<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">
c) Create TestPersonBean class which will just loads the beans.xml and test the person
bean life cycle
import org.springframework.context.ApplicationContext; import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; public class TestPersonBean { public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml"); ("personBean");PersonBean bean =^ (PersonBean)context.getBean System.out.println(bean.getName()); ((AbstractApplicationContext) context).registerShutdownHook (); }
We can configure the default init-method and destroy-method which will be applied on
all the beans .They are useful when we have a pattern of defining common method
names such as init() and destroy() for all your beans consistently.
7.4.1 Example
Write and example to show the init-method and destroy-method
Solution
a)Write a class CustomLifeCycleMehodBean
public class CustomLifeCycleMethodBean { private String name;
public CustomLifeCycleMethodBean() { System.out.println("Constructor of bean is called !! "); }
public void customDestroy() throws Exception {
called !! ");^ System.out.println("custom^ destroy method^ of^ bean^ is
public void customInit() throws Exception { System.out.println("custom Init method of bean is called !! "); }
public String getName() { return name; }
public void setName(String name) { this.name = name; }
b) Create a beans.xml file in src directory to define the CustomMethodLifeCycleBean
d)Run the Program
You will see below output and custom life cycle methods are getting called
7.4.2 – Example
Write an example to demonstrate global init and destroy methods
Solution
a)Write a class CustomGlobalLifeCycleMehodBean
public class CustomGlobalLifeCycleMehodBean { public CustomGlobalLifeCycleMehodBean() { System.out.println("Constructor of bean is called !! "); } public void globalCustomDestroy() throws Exception { called !! ");System.out.println("global^ custom^ destroy^ method^ of^ bean^ is } public void globalCustomInit() throws Exception { System.out.println("global custom Init method of bean is called !! ");
b) Create a beans.xml file in src directory to define the
CustomGlobalMethodLifeCycleBean
c) Create TestCustomMethodLifeCycleBean class which will just loads the beans.xml
and test the custom methods life cycle
import org.springframework.context.ApplicationContext; import org.springframework.context.support.AbstractApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext;
public class TestCustomGlobalMethodLifeCycleBean {
