Running code after Spring Boot starts

Question

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

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Providing an example for Dave Syer answer  which worked like a charm    Component public class CommandLineAppStartupRunner implements CommandLineRunner       private static final Logger logger   LoggerFactory getLogger CommandLineAppStartupRunner class         Override     public void run String   args  throws Exception           logger info  Application started with command-line arguments        n To kill this application  press Ctrl   C    Arrays toString args

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You can extend a class using ApplicationRunner   override the run   method and add the code there    import org springframework boot ApplicationRunner    Component public class ServerInitializer implements ApplicationRunner         Override     public void run ApplicationArguments applicationArguments  throws Exception              code goes here

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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

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Best way to execute block of code after Spring Boot application started is using PostConstruct annotation Or also you can use command line runner for the same   1  Using PostConstruct annotation   Configuration public class InitialDataConfiguration         PostConstruct     public void postConstruct             System out println  Started after Spring boot application                 2  Using command line runner bean   Configuration public class InitialDataConfiguration         Bean     CommandLineRunner runner             return args - gt                System out println  CommandLineRunner running in the UnsplashApplication class

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just implement CommandLineRunner for spring boot application  You need to implement run method   public classs SpringBootApplication implements CommandLineRunner        Override         public void run String    arg0  throws Exception              write your logic here

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I really like the suggestion for usage of the EventListener annotation by  cahen  https   stackoverflow com a 44923402 9122660  since it is very clean  Unfortunately I could not get this to work in a Spring   Kotlin setup  What does work for Kotlin is adding the class as a method parameter     EventListener  fun doSomethingAfterStartup event  ApplicationReadyEvent        System out println  hello world  I have just started up

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you can use  Component  RequiredArgsConstructor  Component  Slf4j public class BeerLoader implements CommandLineRunner         declare        Override     public void run String    args  throws Exception             some code here

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Use a SmartInitializingSingleton bean in spring   4 1   Bean public SmartInitializingSingleton importProcessor         return    - gt            doStuff                As alternative a CommandLineRunner bean can be implemented or annotating a bean method with  PostConstruct

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ApplicationReadyEvent is really only useful if the task you want to perform is not a requirement for correct server operation  Starting an async task to monitor something for changes is a good example   If  however your server is in a  not ready  state until the task is completed then it s better to implement SmartInitializingSingleton because you ll get the callback before your REST port has been opened and your server is open for business   Don t be tempted to use  PostConstruct for tasks that should only happen once ever  You ll get a rude surprise when you notice it being called multiple times

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Best way you use CommandLineRunner or ApplicationRunner The only difference between is run   method CommandLineRunner accepts array of string and ApplicationRunner accepts  ApplicationArugument

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With spring configuration     Configuration public class ProjectConfiguration       private static final Logger log       LoggerFactory getLogger ProjectConfiguration class        EventListener ApplicationReadyEvent class     public void doSomethingAfterStartup         log info  hello world  I have just started up

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Have you tried ApplicationReadyEvent   Component public class ApplicationStartup  implements ApplicationListener lt ApplicationReadyEvent gt                This event is executed as late as conceivably possible to indicate that       the application is ready to service requests           Override   public void onApplicationEvent final ApplicationReadyEvent event            here your code          return         Code from  http   blog netgloo com 2014 11 13 run-code-at-spring-boot-startup  This is what the documentation mentions about the startup events       Application events are sent in the following order  as your application runs  An ApplicationStartedEvent is sent at the start of a run  but before any processing except the registration of listeners and initializers  An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context is known  but before the context is created  An ApplicationPreparedEvent is sent just before the refresh is started  but after bean definitions have been loaded  An ApplicationReadyEvent is sent after the refresh and any related callbacks have been processed to indicate the application is ready to service requests  An ApplicationFailedEvent is sent if there is an exception on startup

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Try    Configuration  EnableAutoConfiguration  ComponentScan public class Application extends SpringBootServletInitializer         SuppressWarnings  resource       public static void main final String   args            ConfigurableApplicationContext context   SpringApplication run Application class  args            context getBean Table class  fillWithTestdata        lt -- here

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The  Spring Boot  way is to use a CommandLineRunner  Just add beans of that type and you are good to go  In Spring 4 1  Boot 1 2  there is also a SmartInitializingBean which gets a callback after everything has initialized  And there is SmartLifecycle  from Spring 3

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Why not just create a bean that starts your monitor on initialization  something like    Component public class Monitor        Autowired private SomeService service       PostConstruct     public void init               start your monitoring in here           the init method will not be called until any autowiring is done for the bean

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Try this one and it will run your code when the application context has fully started     Component public class OnStartServer implements ApplicationListener lt ContextRefreshedEvent gt          Override     public void onApplicationEvent ContextRefreshedEvent arg0                       EXECUTE YOUR CODE HERE

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