增加hasListener判断

hsweb-core/src/main/java/org/hswebframework/web/event/DefaultAsyncEvent.java

@@ -10,7 +10,10 @@ public class DefaultAsyncEvent implements AsyncEvent {
     @Getter
     private Mono<Void> async = Mono.empty();
 
+    private boolean hasListener;
+
     public synchronized void async(Publisher<?> publisher) {
+        hasListener = true;
         this.async = async.then(Mono.from(publisher).then());
     }
 
@@ -21,4 +24,8 @@ public class DefaultAsyncEvent implements AsyncEvent {
 
         return this.async;
     }
+
+    public boolean hasListener() {
+        return hasListener;
+    }
 }