如何使用spring配置Async和Sync Event发布者

Question

我试图使用spring事件实现一个事件框架.我发现spring事件框架的默认行为是sync.但是在spring上下文初始化期间,如果它找到一个id为applicationEventMulticaster的bean,它会表现为异步.

现在我想在我的应用程序中同时拥有同步和异步事件发布者,因为某些事件需要同步发布.我尝试使用SysncTaskExecutor配置同步事件多播器,但我无法找到将其注入我的AsyncEventPublisher的applicationEventPublisher属性的方法.我的弹簧配置文件如下

<bean id="taskExecutor" class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor" destroy-method="shutdown">
        <property name="corePoolSize" value="5" />
        <property name="maxPoolSize" value="10" />
        <property name="WaitForTasksToCompleteOnShutdown" value="true" />
    </bean>  

    <bean id="syncTaskExecutor" class="org.springframework.core.task.SyncTaskExecutor" />

    <bean id="customEventPublisher" class="x.spring.event.CustomEventPublisher" />
    <bean id="customEventHandler" class="x.spring.event.CustomEventHandler" />  
    <bean id="eventSource" class="x.spring.event.EventSource" /> 
    <bean id="responseHandler" class="x.spring.event.ResponseHandler" /> 
    <bean id="syncEventSource" class="x.spring.event.syncEventSource" /> 


    <bean id="applicationEventMulticaster" class="org.springframework.context.event.SimpleApplicationEventMulticaster">
        <property name="taskExecutor" ref="taskExecutor" />         
    </bean>    

    <bean id="syncApplicationEventMulticaster" class="org.springframework.context.event.SimpleApplicationEventMulticaster">
        <property name="taskExecutor" ref="syncTaskExecutor" />         
    </bean>    

有人可以帮我从这里出去吗 ？

Answer 1

我只需要自己解决这个问题。默认情况下，事件是异步发送的，除非您实现了标记接口，在我的例子中，我将其称为 SynchronousEvent。您的配置中也需要一个“执行器”（我省略了我的，因为它是相当定制的）。

@EnableAsync
@SpringBootConfiguration
public class BigFishConfig {

    @Autowired AsyncTaskExecutor executor;

    @Bean
    public ApplicationEventMulticaster applicationEventMulticaster() {
        log.debug("creating multicaster");
        return new SimpleApplicationEventMulticaster() {
            @Override
            public void multicastEvent(final ApplicationEvent event, @Nullable ResolvableType eventType) {
                ResolvableType type = eventType != null ? eventType : ResolvableType.forInstance(event);
                if (event instanceof PayloadApplicationEvent 
                        && ((PayloadApplicationEvent<?>) event).getPayload() instanceof SynchronousEvent) 
                    getApplicationListeners(event, type).forEach(l -> invokeListener(l, event));
                else 
                    getApplicationListeners(event, type).forEach(l -> executor.execute(() -> invokeListener(l, event)));
            }
        };
    }
...

Answer 2

不，你不能这样做，spring的initApplicationEventMulticaster只是init了一个，并且BeanName必须是applicationEventMulticaster。所以你只需选择以下执行器之一：

- org.springframework.core.task.SyncTaskExecutor

- org.springframework.core.task.SimpleAsyncTaskExecutor

- 你自己的执行器：org.springframework.scheduling.concurrent.ThreadPoolTask​​Executor

不管怎样，你可以修改 org.springframework.context.event.SimpleApplicationEventMulticaster 添加你的逻辑，然后你可以控制是否需要同步/异步

    /**
 * 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 + "]");
        }
    }
}