序
本文主要介绍下如何在spring中进行发布时间以及接收事件
定义事件
public class DemoEvent extends ApplicationEvent {
private String message;
public DemoEvent(Object source, String message) {
super(source);
this.message = message;
}
public String getMessage() {
return message;
}
}
发布事件
@Autowired
private ApplicationEventPublisher applicationEventPublisher;
@GetMapping("/send-event")
public Object sendEvent(@RequestParam String msg){
DemoEvent demoEvent = new DemoEvent(this,msg);
applicationEventPublisher.publishEvent(demoEvent);
LOGGER.info("finish publish event");
return "success";
}
这里在mvc中发布,仅仅是为了演示。
接收事件(默认同步
)
@Component
public class DemoEventListener implements ApplicationListener<DemoEvent>{
private static final Logger LOGGER = LoggerFactory.getLogger(DemoEventListener.class);
@Override
public void onApplicationEvent(DemoEvent demoEvent) {
LOGGER.info("receive event:{}",demoEvent.getMessage());
}
}
这里是同步接收
异步处理事件
@Configuration
public class AsyncEventConfig {
@Bean(name = "applicationEventMulticaster")
public ApplicationEventMulticaster simpleApplicationEventMulticaster() {
SimpleApplicationEventMulticaster eventMulticaster
= new SimpleApplicationEventMulticaster();
eventMulticaster.setTaskExecutor(new SimpleAsyncTaskExecutor());
return eventMulticaster;
}
}
加上这个配置就ok了,不然要注意,这里自己new的task executor,要优雅关闭的话,需要自己shutdown
SimpleApplicationEventMulticaster
spring-context-4.3.11.RELEASE-sources.jar!/org/springframework/context/event/SimpleApplicationEventMulticaster.java
@Override
public void multicastEvent(ApplicationEvent event) {
multicastEvent(event, resolveDefaultEventType(event));
}
@Override
public void multicastEvent(final ApplicationEvent event, ResolvableType eventType) {
ResolvableType type = (eventType != null ? eventType : resolveDefaultEventType(event));
for (final ApplicationListener<?> listener : getApplicationListeners(event, type)) {
Executor executor = getTaskExecutor();
if (executor != null) {
executor.execute(new Runnable() {
@Override
public void run() {
invokeListener(listener, event);
}
});
}
else {
invokeListener(listener, event);
}
}
}
private ResolvableType resolveDefaultEventType(ApplicationEvent event) {
return ResolvableType.forInstance(event);
}
可以看到,使用applicationEventMulticaster的时候,如果有线程池,则用线程池异步执行;否则则知直接调用listener的执行方法同步执行。
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