How to configure Async and Sync Event publishers using spring

Question

I am trying to implement an event framework using spring events.I came to know that the default behavior of spring event framework is sync. But during spring context initial

Answer 1

no, you can't do that, the spring initApplicationEventMulticaster just init only one, and the BeanName must be applicationEventMulticaster. so you just can choose one of below Executor:

- org.springframework.core.task.SyncTaskExecutor

- org.springframework.core.task.SimpleAsyncTaskExecutor

- your own Executor: org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor

any way, you can modify org.springframework.context.event.SimpleApplicationEventMulticaster to add your logic, then you can control whether need to Sync/Async

    /**
 * Initialize the ApplicationEventMulticaster.
 * Uses SimpleApplicationEventMulticaster if none defined in the context.
 * @see org.springframework.context.event.SimpleApplicationEventMulticaster
 */
protected void initApplicationEventMulticaster() {
    ConfigurableListableBeanFactory beanFactory = getBeanFactory();
    if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
        this.applicationEventMulticaster =
                beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
        if (logger.isDebugEnabled()) {
            logger.debug("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
        }
    }
    else {
        this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
        beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
        if (logger.isDebugEnabled()) {
            logger.debug("Unable to locate ApplicationEventMulticaster with name '" +
                    APPLICATION_EVENT_MULTICASTER_BEAN_NAME +
                    "': using default [" + this.applicationEventMulticaster + "]");
        }
    }
}