如何为两个片段和一个 activity 创建共享 webSocket？

Question

现在我的应用程序只有一个 activity，它完全支持带有侦听器的 WS 操作并创建新的 webSocket 实例。我想把它分解成一个 activity，它就像是几个片段的支架。

一开始我想在 activity 中创建 webSocket，然后在片段上使用创建的 webSocket。我使用 okHttp3 websockets。一般来说，我可以创建一个单独的 viewModel，我将在其中初始化 websocket，但我还需要在 WS 创建期间传递监听器：

val loggingInterceptor: HttpLoggingInterceptor = HttpLoggingInterceptor()
            .setLevel(HttpLoggingInterceptor.Level.BODY)


val client = OkHttpClient.Builder()
            .addInterceptor(AuthToken(this))
            .addInterceptor(loggingInterceptor)
            .build()

val request = Request.Builder()
            .url(
                BuildConfig.CHAT_URL + UtilsClass.userInfo.applicant?.id + "/"
            )
            .addHeader("Sec-WebSocket-Protocol","android")
            .build()


val ws = client.newWebSocket(request, listener) <---- here

另一方面，我需要为不同的片段设置不同的监听器。 .newWebSocket(... 的调用将创建一个新的 webSocket 实例，这对我不利。但是当我将拥有一个共享的 webSocket 侦听器时，我将需要处理我等待信息的片段。也可能我决定做错了，这不会好。

Answer 1

要使用此解决方案，您必须熟悉这些基础知识

MVVM 架构
Kotlin 流程（响应式编程）

首先，创建一个密封数据class来处理socket事件：

sealed class SocketEvent {
    object OpenEvent : SocketEvent()
    data class CloseEvent(val code: Int, val reason: String) : SocketEvent()
    data class Error(val error: Throwable) : SocketEvent()
    data class StringMessage(val content: String) : SocketEvent()
}

其次，您必须创建一个视图模型 class 来保存网络套接字对象，如下所示：

class SocketViewModel : ViewModel() {


    private lateinit var client: OkHttpClient
    private lateinit var socket: WebSocket

    private fun attachWebSocketListener(webListener: WebSocketListener) {
        client = OkHttpClient()
        val request = Request.Builder().url("http://195.201.167.116:9502").build()
        socket = client.newWebSocket(request, webListener)
    }

    suspend fun socketEventsFlow(): Flow<SocketEvent?> = callbackFlow {
        Timber.tag("soxum").d("opening socket")
        val socketListener = object : WebSocketListener() {
            override fun onMessage(webSocket: WebSocket, text: String) {
                trySendBlocking(SocketEvent.StringMessage(text))
            }

            override fun onOpen(webSocket: WebSocket, response: Response) {
                trySendBlocking(SocketEvent.OpenEvent)
            }

            override fun onClosed(webSocket: WebSocket, code: Int, reason: String) {
                trySendBlocking(SocketEvent.CloseEvent(code, reason))
            }

            override fun onFailure(webSocket: WebSocket, t: Throwable, response: Response?) {
                trySendBlocking(SocketEvent.Error(t))
                cancel("", t)
            }
        }
        attachWebSocketListener(socketListener)
        awaitClose { socket.cancel() }
    }.flowOn(Dispatchers.IO).shareIn(viewModelScope, SharingStarted.Lazily)
}

在您的片段初始视图模型中，您的视图模型取决于父视图模型 activity :

 class FirstFragment : Fragment() {

    private val viewModel by activityViewModels<SocketViewModel>()


    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {

        lifecycleScope.launch {
            viewLifecycleOwner.repeatOnLifecycle(Lifecycle.State.STARTED) {
                viewModel.socketEventsFlow.collectLatest {
                    // TODO get event and do what you want to to
                }
            }
        }
        return inflater.inflate(
            R.layout.fragment_first,
            container,
            false
        )

    }
    
}

activity代码：

class MainActivity : AppCompatActivity() {

    private val viewModel by viewModels<SocketViewModel>()

    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        lifecycleScope.launch {
            lifecycle.repeatOnLifecycle(Lifecycle.State.STARTED) {
                viewModel.socketEventsFlow.collectLatest {
                    // TODO get event and do what you want to to
                }
            }
        }
     }
}

如何为两个片段和一个 activity 创建共享 webSocket？

How to create shared webSocket for two fragments and one activity?

android

websocket

android-fragments