CODEWITHSUNDEEP
javaspringspring-bootspring-mvc
SiriusBits
SiriusBits

Reputation: 790

Spring Boot - Correct way to run code during / before app startup?

There seem to be differing opinions on implementing logic in a Spring Boot web application on startup. But no consensus on "best practice" or a preferred way over others etc.

I have the following code that implements the ApplicationRunner Interface on startup (with some dummy output):

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class AppStartupRunner implements ApplicationRunner {

    public static int counter;

    @Override
    public void run(ApplicationArguments args) throws Exception {
        log.info("Application started with option names : {}",
                args.getOptionNames());
        log.info("Increment counter");
        counter++;
    }
}

Is this method considered "proper" (for lack of a better term)? My intention is to run some code to fetch values on startup from a database, store them in using Ehcache, and a few other "initializing" bits.

This seems hackish, so not sure if there is a cleaner or more appropriate way to go about this.

Upvotes: 8

Views: 3886

Answers (1)

LppEdd
LppEdd

Reputation: 21134

ApplicationRunner and CommandLineRunner are the correct interfaces to implement to execute business logic which require injected dependencies at start-up. There is not much difference between the two.

CommandLineRunner will give you access to the raw String array of parameters passed at startup.
ApplicationRunner will give you a more structured ApplicationArguments, but that's all.

You can have multiple start-up runners, and you can even order them.

This seems hackish

No, it's not. ApplicationRunner and CommandLineRunner JavaDoc

Interface used to indicate that a bean should run when it is contained within a SpringApplication.

Upvotes: 5

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