Skip to main content

Spring boot application events

Spring boot provides an easy and quick way to implement the event listeners. Spring boot generates multiple events during it's application lifecycle. We will see the below events which are provided by spring application under "org.springframework.boot.context.event" Java package. Thanks to spring that we don't need to focus on writing the listeners but the business logics which we want to execute during a specific event and to do that we just need to annotate our business method with @EventListener.

  • ApplicationContextInitializedEvent

Event published when a SpringApplication is starting up and the ApplicationContext is prepared and ApplicationContextInitializers have been called but before any bean definitions are loaded.

Implementation and code example

  • ApplicationEnvironmentPreparedEvent

Event published when a SpringApplication is starting up and the Environment is first available for inspection and modification.

Implementation and code example

  • ApplicationFailedEvent

Event published by a SpringApplication when it fails to start.

Implementation and code example

  • ApplicationPreparedEvent

Event published as when a SpringApplication is starting up and the ApplicationContext is fully prepared but not refreshed. The bean definitions will be loaded and the Environment is ready for use at this stage.
For implementation you can refer any of the other events defined here, for example:- ApplicationReadyEvent or ApplicationStartedEvent in below sections.

  • ApplicationReadyEvent

Event published as late as conceivably possible to indicate that the application is ready to service requests. The source of the event is the SpringApplication itself, but beware of modifying its internal state since all initialization steps will have been completed by then.

Implementation and code example

  • ApplicationStartedEvent

Event published once the application context has been refreshed but before any application and command line runners have been called.

Implementation and code example

  • ApplicationStartingEvent

Event published as early as conceivably possible as soon as a SpringApplication has been started - before the Environment or ApplicationContext is available, but after the ApplicationListeners have been registered. The source of the event is the SpringApplication itself, but beware of using its internal state too much at this early stage since it might be modified later in the lifecycle.

Implementation and code example





Comments

Popular Posts

Setting up kerberos in Mac OS X

Kerberos in MAC OS X Kerberos authentication allows the computers in same domain network to authenticate certain services with prompting the user for credentials. MAC OS X comes with Heimdal Kerberos which is an alternate implementation of the kerberos and uses LDAP as identity management database. Here we are going to learn how to setup a kerberos on MAC OS X which we will configure latter in our application. Installing Kerberos In MAC we can use Homebrew for installing any software package. Homebrew makes it very easy to install the kerberos by just executing a simple command as given below. brew install krb5 Once installation is complete, we need to set the below export commands in user's profile which will make the kerberos utility commands and compiler available to execute from anywhere. Open user's bash profile: vi ~/.bash_profile Add below lines: export PATH=/usr/local/opt/krb5/bin:$PATH export PATH=/usr/local/opt/krb5/sbin:$PATH export LDFLAGS=...

Why HashMap key should be immutable in java

HashMap is used to store the data in key, value pair where key is unique and value can be store or retrieve using the key. Any class can be a candidate for the map key if it follows below rules. 1. Overrides hashcode() and equals() method.   Map stores the data using hashcode() and equals() method from key. To store a value against a given key, map first calls key's hashcode() and then uses it to calculate the index position in backed array by applying some hashing function. For each index position it has a bucket which is a LinkedList and changed to Node from java 8. Then it will iterate through all the element and will check the equality with key by calling it's equals() method if a match is found, it will update the value with the new value otherwise it will add the new entry with given key and value. In the same way it check for the existing key when get() is called. If it finds a match for given key in the bucket with given hashcode(), it will return the value other...

Singleton class in java

What is Singleton class Singleton is a design technique which gaurantees that there will be only instance of a class globally. Such classes are required when we need to create some objects which are memory/ resource extensive and we can't afford many such objects. Using singleton We can maintain single object per JVM per classloader. Classloader could be different in different hierarchy and in such case we may have more than one instances of singleton but we can avoid it by loading it at appropriate classloader. For example in an ear application there could be multiple web modules and each one of them will have their own singleton instance. Sometimes it may be a need but sometimes it could be a flaw which can be resolved by loading it either at ear level or web module level as per requirement. Implementing singleton class There are two different ways to implement singleton in java. Using singleton design pattern In this pattern we can create singleton either using lazy...

Microservices with Spring Boot - complete tutorial

In this tutorial we are going to learn how to develop microservices using spring boot with examples. Main focus of this tutorial is on learning by doing hands-on. Before hands-on we will first understand what is microservices and related terminologies like DDD, 12-Factors App, Dev Ops. What is a Microservice In simple terms microservice is a piece of software which has a single responsibility and can be developed, tested & deployed independently. In microservices we focus on developing independent and single fully functioning modules. Opposite to microservice, with monolithic application it focuses on all the functionality or modules in a single application. So when any changes required to monolithic application it has to deploy and test the complete application while with microservice it has to develop and deploy only affected component which is a small service. It saves lot of development and deployment time in a large application. It's basically an architectural style ...