Java EE 7 containers: initialize bean at startup without adding it to beans.xml?

问题

Is there any bean type or Java EE annotation to get a bean initialized at container startup without adding the bean to beans.xml?

回答1:

Yes, there is.
This is what I use when I need a singleton, application scoped bean started on deploy:

import javax.ejb.Singleton;
import javax.ejb.Startup;
import javax.enterprise.context.ApplicationScoped;
import javax.inject.Named;
import javax.annotation.PostConstruct;

@Named( "myBean" )
@ApplicationScoped
@Startup
@Singleton
public class MyBean {
    @PostConstruct
    public void postConstruct() {}
}

The postConstruct method is added if you need any code to be executed besides initialization.

回答2:

You can use a Singleton bean as shown in Initializing Singleton Session Beans:

import javax.ejb.Singleton;
import javax.ejb.Startup;

@Startup
@Singleton
public class StartupBean {

}

来源：https://stackoverflow.com/questions/46750356/java-ee-7-containers-initialize-bean-at-startup-without-adding-it-to-beans-xml