提交：测试回调只会调用一次，没问题；

lib/amap_navigation_widget.dart

@@ -54,6 +54,7 @@ class _MapNavigationState extends State<AMapNavigationWidget> {
   _connectStreams() {
     print("---_connectStreams---");
     if (widget.onMapClosed != null) {
+      print("------ _connectStreams listen ----- ");
       _methodChannel.onMapClosed().listen((MapClosedEvent e) => widget.onMapClosed!());
     }
   }
@@ -63,7 +64,8 @@ class _MapNavigationState extends State<AMapNavigationWidget> {
     print("------_handleMethodCall ----- ");
     switch (call.method) {
       case 'navigationClosed':
-        _methodChannel.getMapEventStreamController().add(MapClosedEvent(""));
+        print("------ navigationClosed ----- ");
+        _methodChannel.getMapEventStreamController().add(MapClosedEvent("退出"));
         break;
     }
   }