看线上代码用了观察者模式，那叫一个优雅，但有隐患

import org.springframework.context.ApplicationEvent;

public class CustomEvent extends ApplicationEvent {
    private final String message;

    public CustomEvent(Object source, String message) {
        super(source);
        this.message = message;
    }

    public String getMessage() {
        return message;
    }
}

import lombok.extern.slf4j.Slf4j;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class CustomEventListenerNo1 implements ApplicationListener<CustomEvent> {

    @Override
    public void onApplicationEvent(CustomEvent event) {
        log.info(" Received custom event - {} ", event.getMessage());
//        throw new RuntimeException("报错了No1");
    }

}

import lombok.extern.slf4j.Slf4j;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class CustomEventListenerNo2 implements ApplicationListener<CustomEvent> {

    @Override
    public void onApplicationEvent(CustomEvent event) {
        log.info(" Received custom event - {} ", event.getMessage());
//        throw new RuntimeException("报错了No2");
    }

}

@Component
public class CustomEventListener {
    @EventListener
    public void handleCustomEvent(CustomEvent event) {
        log.info(" Received custom event - {} ", event.getMessage());
    }
}

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class CustomEventRunner implements CommandLineRunner {

    private final CustomEventPublisher customEventPublisher;

    @Autowired
    public CustomEventRunner(CustomEventPublisher customEventPublisher) {
        this.customEventPublisher = customEventPublisher;
    }

    @Override
    public void run(String... args) throws Exception {
        String msg = "Hello, this is a custom event!";
        log.info(" begin to publish {} ", msg);
        customEventPublisher.publish(msg);
        log.info(" end to publish {} ", msg);
    }


}

2024-10-24 21:42:29.979  INFO 46572 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 80 (http) with context path ''
2024-10-24 21:42:29.992  INFO 46572 --- [           main] com.tree.thrive.TopTreeApplication       : Started TopTreeApplication in 2.946 seconds (JVM running for 8.911)
2024-10-24 21:42:29.994  INFO 46572 --- [           main] c.t.thrive.adapter.log.LogAppenderInit   : --- LogAppenderInit start ---
2024-10-24 21:42:29.995  INFO 46572 --- [           main] c.t.thrive.adapter.log.LogAppenderInit   : --- LogAppenderInit end ---
2024-10-24 21:42:29.995  INFO 46572 --- [           main] c.t.t.business.event.CustomEventRunner   :  begin to publish Hello, this is a custom event! 
2024-10-24 21:42:29.995  INFO 46572 --- [           main] c.t.t.b.event.CustomEventListenerNo1     :  Received custom event - Hello, this is a custom event! 
2024-10-24 21:42:29.995  INFO 46572 --- [           main] c.t.t.b.event.CustomEventListenerNo2     :  Received custom event - Hello, this is a custom event! 
2024-10-24 21:42:29.995  INFO 46572 --- [           main] c.t.t.business.event.CustomEventRunner   :  end to publish Hello, this is a custom event!

  @Override
  public void multicastEvent(final ApplicationEvent event, @Nullable ResolvableType eventType) {
    ResolvableType type = (eventType != null ? eventType : resolveDefaultEventType(event));
    Executor executor = getTaskExecutor();
    for (ApplicationListener<?> listener : getApplicationListeners(event, type)) {
      if (executor != null) {
        executor.execute(() -> invokeListener(listener, event));
      }
      else {
        invokeListener(listener, event);
      }
    }
  }

@Component
public class AsyncCustomEventListener {
    @Async
    @EventListener
    public void handleCustomEvent(CustomEvent event) {
        // 异步处理事件
    }
}

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