无法在 Spring 引导应用程序中刷新现有的 singleton bean

Question

I have a configuration defined in my spring boot applocation as follows:

@Configuration
public class RuleEngineConfiguration {

  private final DatabaseRuleLoader databaseRuleLoader;

  public RuleEngineConfiguration(
      DatabaseRuleLoader databaseRuleLoader) {
    this.databaseRuleLoader = databaseRuleLoader;
  }

  @Bean
  public RuleEngineManager ruleEngine() {
    return RuleEngineManagerFactory.getRuleEngineManager(this.databaseRuleLoader);
  }

Now I would like to refresh RuleEngineManager bean in my spring boot application on creating/update of a row in a given table in DB with refresh function as defined below:

public void refresh() {
    databaseRuleLoader.refresh(); <---THIS RELOADS ROWS FROM DB
    BeanDefinitionRegistry registry = (BeanDefinitionRegistry) applicationContext
        .getAutowireCapableBeanFactory();
    RuleEngineManager ruleEngineManager = RuleEngineManagerFactory
        .getRuleEngineManager(databaseRuleLoader);
    registry.removeBeanDefinition("ruleEngine");
    ((SingletonBeanRegistry) registry).registerSingleton("ruleEngine", ruleEngineManager);
  }

And in my application, where I need RuleEngineManager bean, I am getting the bean as follows:

((RuleEngineManager) applicationContext.getBean("ruleEngine"))

Even though the refresh function is getting executed every time, I am creating/updating any rows in DB, but, I am not seeing any changes. It seems the existing RuleEnginemanager bean is getting injected as a dependency. I am not able to figure out what I am missing here.

Could anyone please help here? Thanks.

Answer 1

What I was suggesting is to use a factory (design pattern)... for example in this way:

// you already have this class
public class RuleEngineManagerFactory{ 
   private DatabaseRuleLoader databaseRuleLoader;
   private RuleEngineManager ruleEngineManager;
   public RuleEngineManagerFactory(DatabaseRuleLoader databaseRuleLoader) {
     this.databaseRuleLoader = databaseRuleLoader;
   }
   public RuleEngineManager getRuleEngineManager(){
     if(this.ruleEngineManager == null){
         ruleEngineManager = new RuleEngineManager(this.databaseRuleLoader);
     }
     return this.ruleEngineManager;
   }
   public void refresh(){
      ruleEngineManager = new RuleEngineManager(this.databaseRuleLoader);
   }
}

In this way, you will inject RuleEngineManagerFactory wherever you need, and you can refresh the RuleEngineManager ... so you will have to have a singleton for the factory of the manager, and not for the manager itself