Flutter EventChannel无法向Dart端传输安卓分享数据问题

已成功将应用加入安卓分享面板，原生侧能正常捕获分享的文本或图片Uri（日志可查），但EventChannel始终无法把数据传到Dart端。MainActivity和AndroidManifest配置已完成，相关代码如下：

MainActivity代码 #

class MainActivity: FlutterActivity() {


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        Log.i("TAG123","onCreate")
        onSharedIntent()
    }

    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        Log.i("TAG123","configure flutter engine")


    }

    private fun onSharedIntent() {
        val receivedAction: String? = intent.action
        val receivedType: String? = intent.type
        if (receivedAction == Intent.ACTION_SEND) {

            // check mime type
            if (receivedType?.startsWith("text/") == true) {
                val receivedText: String? = intent.getStringExtra(Intent.EXTRA_TEXT)
                if (receivedText != null) {
                    //do your stuff
                    Log.e("TAG123", receivedText.toString())
                    if(flutterEngine?.dartExecutor?.binaryMessenger != null){
                        Log.i("TAG123","flutter engine not null")
                    }
                    Log.e("TAG123", "here")
                    EventChannel(
                        flutterEngine!!.dartExecutor.binaryMessenger,
                        "sharePlatform"
                    ).setStreamHandler(object : EventChannel.StreamHandler {

                        override fun onListen(arguments: Any, events: EventSink) {
                            Log.e("TAG123", "here123")
                            events.success(receivedText)
                        }

                        override fun onCancel(arguments: Any) {
                            Log.e("TAG123", "here123456")
                        }
                    })
                } else {
                    Log.e("TAG123", "no data")
                }
            } else if (receivedType?.startsWith("image/") == true) {
//                val receiveUri: Uri? = intent.getParcelableExtra(Intent.EXTRA_STREAM) as Uri?

                val receiveUri = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
                    intent.getParcelableExtra(Intent.EXTRA_STREAM, Uri::class.java)
                } else {
                    intent.getParcelableExtra(Intent.EXTRA_STREAM) as Uri?
                }

                if (receiveUri != null) {
                    Log.e("TAG123", receiveUri.toString())
                    if(flutterEngine?.dartExecutor?.binaryMessenger != null){
                        Log.i("TAG123","flutter engine not null")
                    }
                    EventChannel(
                        flutterEngine!!.dartExecutor.binaryMessenger,
                        "sharePlatform"
                    ).setStreamHandler(object : EventChannel.StreamHandler {

                        override fun onListen(arguments: Any, events: EventSink) {
                            Log.e("TAG123", "here123")
                            events.success(receiveUri)
                        }

                        override fun onCancel(arguments: Any) {
                            Log.e("TAG123", "here123456")
                        }
                    })
                } else {
                    Log.e("TAG123", "no image data")
                }
            }
        } else if (receivedAction == Intent.ACTION_MAIN) {
            Log.e("TAG123", "onSharedIntent: nothing shared")
        }
    }

}

AndroidManifest配置 #

<intent-filter>
                <action android:name="android.intent.action.SEND" />

                <category android:name="android.intent.category.DEFAULT" />
                <data android:mimeType="image/*" />
                <data android:mimeType="text/*" />
            </intent-filter>

Dart代码 #

class _MyHomePageState extends State<MyHomePage> {
  var data = "";
  final _eventChannel = const EventChannel('sharePlatform');

  @override
  void initState() {
    super.initState();

    _eventChannel.receiveBroadcastStream().distinct().map((dynamic event) {
      debugPrint("TAG123Flutter $event");
      setState(() {
        data = event;
      });
      // return event;
    });
  }......

核心问题点 #

1. EventChannel初始化时机不对：onCreate调用onSharedIntent时，Flutter Engine还没完成初始化（configureFlutterEngine在onCreate之后执行），此时设置的StreamHandler无法被Dart端监听。
2. Uri无法直接传递：原生Uri对象不能直接通过EventChannel序列化传给Dart，必须转成字符串。
3. Dart端未正确订阅流：map只是数据转换操作，不会触发流订阅，必须调用listen才能生效。

修复步骤 #

1. 调整原生侧代码逻辑

把EventChannel的配置移到configureFlutterEngine中，先缓存分享数据，等Engine初始化完成后再传递：

class MainActivity: FlutterActivity() {
    private var sharedData: Any? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        Log.i("TAG123","onCreate")
        // 先缓存分享数据
        sharedData = getSharedContent()
    }

    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        Log.i("TAG123","configure flutter engine")
        
        // 初始化EventChannel并设置StreamHandler
        EventChannel(flutterEngine.dartExecutor.binaryMessenger, "sharePlatform")
            .setStreamHandler(object : EventChannel.StreamHandler {
                override fun onListen(arguments: Any?, events: EventSink) {
                    Log.e("TAG123", "onListen triggered")
                    sharedData?.let { data ->
                        // Uri转字符串传递
                        val sendData = if (data is Uri) data.toString() else data
                        events.success(sendData)
                    } ?: events.error("NO_DATA", "无分享数据", null)
                }

                override fun onCancel(arguments: Any?) {
                    Log.e("TAG123", "onCancel triggered")
                }
            })
    }

    // 提取分享数据的独立方法
    private fun getSharedContent(): Any? {
        val receivedAction = intent.action
        val receivedType = intent.type
        if (receivedAction == Intent.ACTION_SEND) {
            return when {
                receivedType?.startsWith("text/") == true -> {
                    intent.getStringExtra(Intent.EXTRA_TEXT)?.also {
                        Log.e("TAG123", "收到文本: $it")
                    }
                }
                receivedType?.startsWith("image/") == true -> {
                    val receiveUri = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
                        intent.getParcelableExtra(Intent.EXTRA_STREAM, Uri::class.java)
                    } else {
                        intent.getParcelableExtra(Intent.EXTRA_STREAM) as Uri?
                    }
                    receiveUri?.also {
                        Log.e("TAG123", "收到图片Uri: $it")
                    }
                }
                else -> null
            }
        }
        Log.e("TAG123", "无分享内容")
        return null
    }

    // 处理应用后台唤起的情况
    override fun onNewIntent(intent: Intent?) {
        super.onNewIntent(intent)
        this.intent = intent
        sharedData = getSharedContent()
        // 重新设置StreamHandler传递新数据
        flutterEngine?.let { engine ->
            EventChannel(engine.dartExecutor.binaryMessenger, "sharePlatform")
                .setStreamHandler(object : EventChannel.StreamHandler {
                    override fun onListen(arguments: Any?, events: EventSink) {
                        sharedData?.let { data ->
                            val sendData = if (data is Uri) data.toString() else data
                            events.success(sendData)
                        } ?: events.error("NO_DATA", "无分享数据", null)
                    }

                    override fun onCancel(arguments: Any?) {}
                })
        }
    }
}

2. 修复Dart端流订阅

确保调用listen触发订阅，同时添加取消订阅的逻辑避免内存泄漏：

class _MyHomePageState extends State<MyHomePage> {
  var data = "";
  final _eventChannel = const EventChannel('sharePlatform');
  StreamSubscription? _dataSubscription;

  @override
  void initState() {
    super.initState();
    _startListeningSharedData();
  }

  void _startListeningSharedData() {
    _dataSubscription = _eventChannel.receiveBroadcastStream()
        .distinct()
        .listen((dynamic event) {
          debugPrint("TAG123Flutter $event");
          setState(() {
            data = event.toString();
          });
        }, onError: (error) {
          debugPrint("接收分享数据出错: $error");
        });
  }

  @override
  void dispose() {
    _dataSubscription?.cancel();
    super.dispose();
  }
  // ... 其他页面代码
}

内容的提问来源于stack exchange，提问作者BraveEvidence