Best way to initialize beans in a spring context after running the application?

Question

I need to initialize beans in a Spring context after starting my application; I am currently initializing beans in a class with the @Configuration annotation as follows:

@Configuration
public class AppConfig {
   @Inject
   @Bean
   public BeanA init(param1, param2, etc...) {
       --- Code to construct bean A ---
   }

   @Inject
   @Bean
   public BeanB init(param1, param2, etc...) {
       --- Code to construct bean B ---
   }
}

But some beans I need to initialize after the application starts, so my approach creates a class that listens for the ApplicationReadyEvent event in Spring and puts the code in the beans initialization in this class.

@Configuration
class ApplicationStartingListener implements ApplicationListener<ApplicationReadyEvent>{
    ---- Code to init bean here ----

    @Override
    public void onApplicationEvent(ApplicationReadyEvent event) {
        --- If I put init bean code in here, is it correct? ----
    }
}

Is this the best way? Or are there other better solutions?

Answer 1

init beans, Spring .

• @PostConstruct: , bean, .
• @Bean(init-method="somInitMehotd"): Spring bean bean, @PostConstruct, @PostConstruct . .
• ApplicationListener: , , . : MyAppListener ApplicationListener<ContextRefreshedEvent>, MyAppListener onApplicationEvent, ContextRefreshedEvent

Spring

4. : CommandLineRunner ApplicationRunner, ApplicationContext, beans .

5. Spring : Spring , , . - ApplicationReadyEvent, , . , ApplicationListener, ApplicationReadyEvent .

:

MyBean , , , Thread.sleep, , .

import javax.annotation.PostConstruct;
public class MyBean {

    private String myVar="";

    public MyBean(){

    }

    @PostConstruct
    public void postConstructInit(){

        this.myVar="Post init called";
        print();

    }

    public void beanInit(){

        this.myVar="Bean init called";
        print();
    }

    public void contextInit(){

        this.myVar="Context init called";
        print();
    }

    public void runnerInit(){

        this.myVar="Runner init called";
        print();
    }

    public void bootListenerInit(){

        this.myVar="Boot init called";
        print();
    }



    public void print(){
        System.out.println(this.myVar);
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

ContextRefreshListener, ContextRefreshedEvent .

public class ContextRefreshListener implements ApplicationListener<ContextRefreshedEvent> {
    @Override
    public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
        contextRefreshedEvent.getApplicationContext().getBean(MyBean.class).contextInit();

    }
}

BootListener ApplicationReadyEvent, Spring Application.

public class MyBootListener implements ApplicationListener<ApplicationReadyEvent> {
    @Override
    public void onApplicationEvent(ApplicationReadyEvent applicationReadyEvent) {
        applicationReadyEvent.getApplicationContext().getBean(MyBean.class).bootListenerInit();
    }
}

, Spring

@SpringBootApplication
public class StackoverflowBootApplication {


    public static void main(String[] args) {

        SpringApplication.run(StackoverflowBootApplication.class, args);

    }

    @Bean(name = "myBean", initMethod = "beanInit")
    public MyBean getMyBean(){
        return new MyBean();
    }


    @Bean
    public ContextRefreshListener getContextRefreshedListener(){return new ContextRefreshListener();}


    @Bean
    public MyBootListener getBootListener(){return new MyBootListener();}

    @Bean
    public CommandLineRunner getRunner(ApplicationContext ctx){
        return (args) -> {
            ctx.getBean(MyBean.class).runnerInit();
        };
    }

}

:

Post init called
Bean init called
Context init called
Runner init called 
Boot init called

Post init called

@PostConstruct
public void init(){
    this.initByPostconstruct="Post init called";

Bean init called initMethod

@Bean(name = "myBean", initMethod = "beanInit")
public MyBean getMyBean(){
    return new MyBean();
}
}

Context init called ContextRefreshedEvent

public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
    contextRefreshedEvent.getApplicationContext().getBean(MyBean.class).contextInit();

}

Runner init called CommandLineRunner

@Bean
public CommandLineRunner getRunner(ApplicationContext ctx){
    return (args) -> {
        ctx.getBean(MyBean.class).runnerInit();
    };
}

Boot init called ApplicationReadyEvent

   public void onApplicationEvent(ApplicationReadyEvent applicationReadyEvent) {
        applicationReadyEvent.getApplicationContext().getBean(MyBean.class).bootListenerInit();
    }

Spring, , Spring Framework.