Gracefully Shutdown Spring Application Container
This tutorial shows you how to register a shutdown hook with the JVM in a non-web application context. By default the ApplicationContext does not have a shutdown hook and does not have any exposed methods to configure this. These methods are all encapsulated in the ConfigurableApplicationContext. This interface exposes a couple of extra configuration and lifecycle management methods like close(); and registerShutdownHook();. When you call the registerShutdownHook() method, this registers a shutdown hook with the JVM and ensures a graceful shutdown and calls the relevant destroy methods on your singleton beans.
Adding init and destroy methods
This spring managed bean has a init and a destroy method. These methods will be called when the bean is created and destroyed.
package com.memorynotfound.spring.core.lifecycle;
public class Logger {
public void init(){
System.out.println("- - - initializing logger bean");
}
public void destroy(){
System.out.println("- - - destroying logger bean");
}
}Configuring the bean
We configure the initializing and destruction methods using xml configuration. The init-method method registers an initialization method that will be called when the bean is created. The destroy-method method registers a destruction method that will be called before the JVM is shutdown. The lifecycle methods will only be invoked on a singleton bean.
<?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 class="com.memorynotfound.spring.core.lifecycle.Logger"
init-method="init"
destroy-method="destroy"/>
</beans>Register a Shutdown hook with the JVM
The ConfigurableApplicationContext exposes the close() and registerShutdownHook() methods. You can explicitly call the close() method. Or call the registerShutdownHook() method. Both must be used in a non-web application context. These methods will call the registered destruction methods of singleton beans before the JVM is closed.
package com.memorynotfound.spring.core.lifecycle;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Run {
public static void main(String... args) throws InterruptedException {
ConfigurableApplicationContext context = new ClassPathXmlApplicationContext("app-config.xml");
// implicit shutdown hook
context.registerShutdownHook();
// or explicit close method
context.close();
}
}Output
As you can see, the destruction method of our singleton bean is called.
- - - initializing logger bean
- - - destroying logger bean
