Java – Running code after Spring Boot starts

javaspringspring-boot

I want to run code after my spring-boot app starts to monitor a directory for changes.

I have tried running a new thread but the @Autowired services have not been set at that point.

I have been able to find ApplicationPreparedEvent, which fires before the @Autowired annotations are set. Ideally I would like the event to fire once the application is ready to process http requests.

Is there a better event to use, or a better way of running code after the application is live in spring-boot?

Best Answer

It is as simple as this:

@EventListener(ApplicationReadyEvent.class)
public void doSomethingAfterStartup() {
    System.out.println("hello world, I have just started up");
}

Tested on version 1.5.1.RELEASE

Related Solutions

Java – What’s the difference between @Component, @Repository & @Service annotations in Spring

From Spring Documentation:

The @Repository annotation is a marker for any class that fulfils the role or stereotype of a repository (also known as Data Access Object or DAO). Among the uses of this marker is the automatic translation of exceptions, as described in Exception Translation.

Spring provides further stereotype annotations: @Component, @Service, and @Controller. @Component is a generic stereotype for any Spring-managed component. @Repository, @Service, and @Controller are specializations of @Component for more specific use cases (in the persistence, service, and presentation layers, respectively). Therefore, you can annotate your component classes with @Component, but, by annotating them with @Repository, @Service, or @Controller instead, your classes are more properly suited for processing by tools or associating with aspects.

For example, these stereotype annotations make ideal targets for pointcuts. @Repository, @Service, and @Controller can also carry additional semantics in future releases of the Spring Framework. Thus, if you are choosing between using @Component or @Service for your service layer, @Service is clearly the better choice. Similarly, as stated earlier, @Repository is already supported as a marker for automatic exception translation in your persistence layer.

Annotation	Meaning
`@Component`	generic stereotype for any Spring-managed component
`@Repository`	stereotype for persistence layer
`@Service`	stereotype for service layer
`@Controller`	stereotype for presentation layer (spring-mvc)

Java – Why does this code using random strings print “hello world”

The other answers explain why, but here is how.

Given an instance of Random:

Random r = new Random(-229985452)

The first 6 numbers that r.nextInt(27) generates are:

and the first 6 numbers that r.nextInt(27) generates given Random r = new Random(-147909649) are:

Then just add those numbers to the integer representation of the character ` (which is 96):

8  + 96 = 104 --> h
5  + 96 = 101 --> e
12 + 96 = 108 --> l
12 + 96 = 108 --> l
15 + 96 = 111 --> o

23 + 96 = 119 --> w
15 + 96 = 111 --> o
18 + 96 = 114 --> r
12 + 96 = 108 --> l
4  + 96 = 100 --> d

Best Answer

Related Solutions

Java – What’s the difference between @Component, @Repository & @Service annotations in Spring

Java – Why does this code using random strings print “hello world”

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