After Flutter1.12 upgrade What is the problem? The type of inventory (attached document to learn)

I have seen the official update log small partners are aware of the new version flutterand Androidthe native interaction there are some changes, mainly in the following sections

1. Custom Plugin class need to implement FlutterPluginthe interface, and implement the following two methods

       @Override
      public void onAttachedToEngine(@NonNull FlutterPluginBinding flutterPluginBinding) { //注册，等同于原来的registerWith
      final MethodChannel channel = new  MethodChannel(flutterPluginBinding.getFlutterEngine().getDartExecutor(), "flutter_wx");
      channel.setMethodCallHandler(new FlutterWxPlugin());
  }

       @Override
        public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
  }

2. Get Flutterdata (method name) needed to achieve the passed MethodCallHandler(and previous versions of the same)

      @Override
      public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
      Log.d(TAG, "onMethodCall:" + activity);
      Toast.makeText(activity, "TestActivity", Toast.LENGTH_SHORT).show();
      if (call.method.equals("getPlatformVersion")) {
        result.success("Android " + android.os.Build.VERSION.RELEASE);
      } else {
        result.notImplemented();
      }
  }

3. Now there is a demand that is needed onMethodCallto obtain activity object methods, the new version provides us with a new interface to make me a better deal Pluginand Activitysome interactive, so we implement ActivityAwarethis interface, the following method overrides, in onAttachedToActivitythe we can binding.getActivity()get the current activityobject, and then assign the global variables we define, this time the question is, we onMethodCallget in the way activityof value is alwaysnull

      @Override
  public void onAttachedToActivity(ActivityPluginBinding binding) {
      Log.d(TAG, "onAttachedToActivity");
      this.activity = binding.getActivity();
  }

  @Override
  public void onDetachedFromActivityForConfigChanges() {

  }

  @Override
  public void onReattachedToActivityForConfigChanges(ActivityPluginBinding binding) {

  }

  @Override
  public void onDetachedFromActivity() {

  }

4. Solution, modified onAttachedToEnginemethod channel.setMethodCallHandler(new FlutterWxPlugin())is channel.setMethodCallHandler(this);

   @Override
      public void onAttachedToEngine(@NonNull FlutterPluginBinding flutterPluginBinding) { //注册，等同于原来的registerWith
      final MethodChannel channel = new  MethodChannel(flutterPluginBinding.getFlutterEngine().getDartExecutor(), "flutter_wx");
      channel.setMethodCallHandler(this);//修改此处为this
  }

5. Summary, the specific cause of the problem has not been studied fine, when the Pluginmethod of replication will be performed twice at initialization time. We look forward to the official solution.

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