Spring InitializingBean Example
October 26, 2021
InitializingBean example. The InitializingBean is an interface containing afterPropertiesSet() method. A bean can use it to perform a task required after the bean properties are set. The BeanFactory invokes afterPropertiesSet() method once the bean properties are initialized. The InitializingBean can be used to validate our properties value or to initialize any task.
Note: The alternative of
InitializingBean is @PostConstruct Annotation.
Maven File
Find the Maven file used in our example.pom.xml
<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.5.5</version> <relativePath /> </parent> <properties> <java.version>16</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> </dependencies>
Implement InitializingBean
TheInitializingBean has following method.
void afterPropertiesSet() throws Exception
BeanFactory invokes the above method once BeanFactory has set all bean properties and satisfied BeanFactoryAware, ApplicationContextAware etc.
Find the code to use
InitializingBean. We are creating a class that is implementing InitializingBean and defining its afterPropertiesSet() method.
Book.java
package com.concretepage;
import org.springframework.beans.factory.InitializingBean;
public class Book implements InitializingBean {
private String bookName;
@Override
public void afterPropertiesSet() {
System.out.println("---Do initialization task---");
if (bookName != null) {
System.out.println("Book Name:" + bookName);
}
}
public String getBookName() {
return bookName;
}
public void setBookName(String bookName) {
this.bookName = bookName;
}
}
<?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.xsd">
<bean id="book" class="com.concretepage.Book">
<property name="bookName" value="Mahabharat"/>
</bean>
</beans>
Run Application
To test the application, run the following main method.
SpringDemo.java
package com.concretepage;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SpringDemo {
public static void main(String[] args) {
AbstractApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
}
}
Find the output.
09:25:02.670 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Invoking afterPropertiesSet() on bean with name 'book'
---Do initialization task---
Book Name:Mahabharat
09:25:02.670 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Finished creating instance of bean 'book'
Reference
Interface InitializingBean
Download Source Code
package com.concretepage;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SpringDemo {
public static void main(String[] args) {
AbstractApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
}
}
09:25:02.670 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Invoking afterPropertiesSet() on bean with name 'book' ---Do initialization task--- Book Name:Mahabharat 09:25:02.670 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Finished creating instance of bean 'book'
