BeanPostProcessor provides a way to perform some operations before creating a spring bean and immediately after creating spring bean. So you can add some logic before and after creating the bean.
Follow steps to implement spring bean post processors –
- Implements BeanPostProcessor in Processor class.
- Overrides methods provided by BeanPostProcessor and add some logic whatever you want in postProcessBeforeInitialization and postProcessAfterInitialization
- Create bean for the class who implement BeanPostProcessor in .xml file
Lets Implement
Project structure be like below image
add a dependency on pom.xml file –
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.3.4.RELEASE</version>
</dependency>
bean class “Greetings.java”
package com.spring.core;
public class Greetings {
private String message;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public void init() {
System.out.println("Init");
}
public void destroy() {
System.out.println("Destroy");
}
}
Processor.java
package com.spring.core;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
public class Processor implements BeanPostProcessor {
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
System.out.println("After Process Initialization Bean - "+bean+" and Name - "+beanName);
return bean;
}
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
System.out.println("Before Process Initialization Bean - "+bean+" and Name - "+beanName);
return bean;
}
}
beans.xml file is in classpath
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN" "http://www.springframework.org/dtd/spring-beans-2.0.dtd"> <beans default-init-method="init" default-destroy-method="destroy"> <bean id="greet" class="com.spring.core.Greetings"> <property name="message" value="Hello One"></property> </bean> <bean id="processor" class="com.spring.core.Processor"></bean> </beans>
Main class
package com.spring.core;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Application {
public static void main(String[] args) {
AbstractApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
Greetings greet = (Greetings) context.getBean("greet");
System.out.println(greet.getMessage());
context.registerShutdownHook();
}
}
Output –
Dec 28, 2016 12:31:32 PM org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@300ffa5d: startup date [Wed Dec 28 12:31:32 IST 2016]; root of context hierarchy Dec 28, 2016 12:31:32 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions INFO: Loading XML bean definitions from class path resource [beans.xml] Before Process Initialization Bean - com.spring.core.Greetings@14bf9759 and Name - greet Init After Process Initialization Bean - com.spring.core.Greetings@14bf9759 and Name - greet Hello One Dec 28, 2016 12:31:32 PM org.springframework.context.support.ClassPathXmlApplicationContext doClose INFO: Closing org.springframework.context.support.ClassPathXmlApplicationContext@300ffa5d: startup date [Wed Dec 28 12:31:32 IST 2016]; root of context hierarchy Destroy
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