树叶云鸿蒙OS教程：鸿蒙OS WLAN消息通知

场景介绍

WLAN 消息通知（Notification）是 HarmonyOS 内部或者与应用之间跨进程通讯的机制，注册者在注册消息通知后，一旦符合条件的消息被发出，注册者即可接收到该消息并获取消息中附带的信息。

接口说明

开发步骤

1. 构建消息通知接收者 WifiEventSubscriber。

1. 注册 WLAN 变化消息。

1. WifiEventSubscriber 接收并处理 WLAN 广播消息。

   // 构建消息接收者/注册者
   class WifiEventSubscriber extends CommonEventSubscriber {
       WifiEventSubscriber (CommonEventSubscribeInfo info) {
           super(info);
       }

    
       @Override
       public void onReceiveEvent(CommonEventData commonEventData) {
           if (WifiEvents.EVENT_ACTIVE_STATE.equals(commonEventData.getIntent().getAction())) {
               // 获取附带参数
               IntentParams params = commonEventData.getIntent().getParams();
               if (params == null) {
                   return;
               }
               int wifiState= (int) params.getParam(WifiEvents.PARAM_ACTIVE_STATE);

               
               if (wifiState== WifiEvents.STATE_ACTIVE) { // 处理WLAN被打开消息
                   HiLog.info(LABEL, false, "Receive WifiEvents.STATE_ACTIVE %{public}d", wifiState);
               } else if (wifiState == WifiEvents.STATE_INACTIVE) { // 处理WLAN被关闭消息  
                   HiLog.info(LABEL, false, "Receive WifiEvents.STATE_INACTIVE %{public}d", wifiState);
               } else { // 处理WLAN异常状态
                   HiLog.info(LABEL, false, "Unknown wifi state");
               }
           }
       }
   }

    
   // 注册消息
   MatchingSkills match = new MatchingSkills();
   // 增加获取WLAN状态变化消息
   filter.addEvent(WifiEvents.EVENT_ACTIVE_STATE);
   CommonEventSubscribeInfo subscribeInfo = new CommonEventSubscribeInfo(match);
   subscribeInfo.setPriority(100); 
   WifiEventSubscriber subscriber = new WifiEventSubscriber(subscribeInfo);

    
   try {
       CommonEventManager.subscribeCommonEvent(subscriber);
   } catch (RemoteException e) {
       HiLog.warn(LABEL, false, "subscribe in wifi events failed!");
   }