Deusnominus's questions

我正在尝试构建一个 android 服务，该服务可继续从与 ble 信标交互的 jetpack compose 应用程序进行蓝牙低功耗扫描。我现在的目标只是在将应用程序置于后台后启动我的前台服务。我的代码编译后，跟踪进程的日志语句会正常显示在我的 logcat 中，但服务进程在启动时就结束了，并且通知永远不会出现在状态栏上。

这是我的蓝牙服务类代码

@AndroidEntryPoint
class BluetoothScanService : Service() {

    @Inject lateinit var bluetoothUtils: BluetoothUtils
    @Inject lateinit var sharedDataManager: SharedDataManager
    @Inject lateinit var bleScanCallback: BleScanCallback

    override fun onCreate() {
        super.onCreate()
        // Initialize your BluetoothUtils, SharedDataManager, and ScanCallback here
        Log.i("foreground", "Inside onCreate in Bluetooth Service")

        val notification = createForegroundNotification()
        startForeground(1, notification)

        Log.i("foreground", "BluetoothUtils: $bluetoothUtils")
    }

    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
        if (intent == null) {
            Log.e("foreground", "Received null intent in onStartCommand")
            return START_NOT_STICKY // or return an appropriate value
        }



        Log.i("foreground", "Inside onStartCommand in Bluetooth Service")
        // Start the Bluetooth scan in the foreground service
        bluetoothUtils.startScanning(bleScanCallback)

        return START_NOT_STICKY
    }

    private fun createForegroundNotification(): Notification {
        val channelId = "BluetoothScanChannel"
        val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

        // Create notification channel for Android 8.0 and above
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            val channel = NotificationChannel(
                channelId,
                "Bluetooth Scan",
                NotificationManager.IMPORTANCE_DEFAULT
            )
            notificationManager.createNotificationChannel(channel)
        }

        // Create the notification
        val notification = NotificationCompat.Builder(this, channelId)
            .setContentTitle("Bluetooth Scanning")
            .setContentText("Bluetooth scanning is running in the background.")
            //.setSmallIcon(R.drawable.ic_bluetooth)
            .build()

        return notification
    }

    override fun onBind(intent: Intent?): IBinder? {
        return null
    }
} 

这就是我从 MainActivity 中的 onPause() 和 onResume() 调用服务的方式（我只有一个活动，因为我正在使用 Jetpack 组合。我的应用程序中的每个屏幕都是可组合的）。

   override fun onPause(){
        super.onPause()
        Log.i("foreground", "Inside onPause in MainActivity")
        val intent = Intent(this, BluetoothScanService::class.java)
        Log.i("foreground", "the intent ${intent}")

        startService(intent)

    }
    override fun onResume() {
        super.onResume()
        Log.i("foreground", "Inside onResume in MainActivity")
        val intent = Intent(this, BluetoothScanService::class.java)
        stopService(intent)

    }

这是我的 logcat 结果

2025-01-21 13:49:32.544 32677-32677 foreground              com.myApp.bleApp              I  Inside onPause in MainActivity
2025-01-21 13:49:32.545 32677-32677 foreground              com.myApp.bleApp              I  the intent Intent { cmp=com.myApp.bleApp/.common.foregroundServices.BluetoothScanService }
2025-01-21 13:49:32.590 32677-32677 foreground              com.myApp.bleApp              I  Inside onCreate in Bluetooth Service
2025-01-21 13:49:32.691 32677-32677 foreground              com.myApp.bleApp              I  BluetoothUtils: com.myApp.bleApp.hardware.bluetooth.BluetoothUtils@7da3008
2025-01-21 13:49:32.693 32677-32677 foreground              com.myApp.bleApp              I  Inside onStartCommand in Bluetooth Service
---------------------------- PROCESS ENDED (32677) for package com.myApp.bleApp ----------------------------

如果我使用 return START_STICKY 而不是 return START_NOT_STICKY，进程仍会结束，但它会以空意图重新启动，并且通知会出现在我的状态栏中。这些是我的 logcat 结果

2025-01-21 13:51:45.677  1960-1960  foreground              com.myApp.bleApp              I  Inside onPause in MainActivity
2025-01-21 13:51:45.678  1960-1960  foreground              com.myApp.bleApp              I  the intent Intent { cmp=com.myApp.bleApp/.common.foregroundServices.BluetoothScanService }
2025-01-21 13:51:45.739  1960-1960  foreground              com.myApp.bleApp              I  Inside onCreate in Bluetooth Service
2025-01-21 13:51:45.809  1960-1960  foreground              com.myApp.bleApp              I  BluetoothUtils: com.myApp.bleApp.hardware.bluetooth.BluetoothUtils@eaa3f16
2025-01-21 13:51:45.811  1960-1960  foreground              com.myApp.bleApp              I  Inside onStartCommand in Bluetooth Service
---------------------------- PROCESS ENDED (1960) for package com.myApp.bleApp ----------------------------
---------------------------- PROCESS STARTED (2496) for package com.myApp.bleApp ----------------------------
2025-01-21 13:51:49.731  2496-2496  foreground              com.myApp.bleApp              I  Inside onCreate in Bluetooth Service
2025-01-21 13:51:49.741  2496-2496  foreground              com.myApp.bleApp              I  BluetoothUtils: com.myApp.bleApp.hardware.bluetooth.BluetoothUtils@861bce1
2025-01-21 13:51:49.742  2496-2496  foreground              com.myApp.bleApp              E  Received null intent in onStartCommand

这是进程结束时出现的错误

致命异常：主进程：com.myApp.bleApp，PID：7298 java.lang.StackOverflowError：堆栈大小 8188KB 位于 com.myapp.bleApp.hardware.bluetooth.bleScanner.BleScanCallback.onScanFailed（BleScanCallback.kt：237）

这就是我的 bleScanCallback 类中的 onScanFailed(errorCode) 发生错误的地方

    override fun onScanFailed(errorCode: Int) {
        super.onScanFailed(errorCode)
        // Handle scan failure
        onScanFailed(errorCode)
    }

我现在唯一想要发生的事情是当应用程序在后台时服务保持活动状态，并且我希望看到通知出现在状态栏中。我该如何解决这个问题？

我正在按照“https://developer.paypal.com/docs/checkout/advanced/android/”添加正确的依赖项以在我的 jetpack compose android 应用程序中使用 paypal，但我收到此错误：“原因：org.gradle.api.internal.artifacts.ivyservice.DefaultLenientConfiguration$ArtifactResolveException：无法解析配置'：app:debugRuntimeClasspath'的所有文件。”

在我开始玩 build.gradle 文件之前，一切都很顺利。

我在 build.gradle 应用文件中添加了以下几行代码：

    implementation("com.paypal.android:card-payments:CURRENT-VERSION-SNAPSHOT")
    implementation("com.paypal.sdk:paypal-android-sdk:2.16.0")

我按照 paypal 网站对项目 build.gradle 文件的要求进行了操作，但收到此错误“Build file 'C:\Users\FookY\AndroidStudioProjects\PaymentProcessing\build.gradle.kts' line: 9

构建配置为优先使用设置存储库而不是项目存储库，但构建文件“build.gradle.kts”添加了存储库“MavenRepo”，因此我将 settings.gradle 文件更改为：

pluginManagement {
    repositories {
        google {
            content {
                includeGroupByRegex("com\\.android.*")
                includeGroupByRegex("com\\.google.*")
                includeGroupByRegex("androidx.*")
            }
        }
        mavenCentral()
        gradlePluginPortal()
    }
}

dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        google()
        mavenCentral()
        maven("https://oss.sonatype.org/content/repositories/snapshots/")
    }
}

rootProject.name = "PaymentProcessing"
include(":app")

现在我收到这个错误

Caused by: org.gradle.api.internal.artifacts.ivyservice.DefaultLenientConfiguration$ArtifactResolveException: Could not resolve all files for configuration ':app:debugRuntimeClasspath'.

我只想理清依赖关系，以便能够使用 paypal sdk。我该如何实现这一点？

我在我的应用程序中创建了一个房间数据库，我可以使用我编写的函数向其中添加数据，但我无法检索它们。 我的目标只是保存用户名和电子邮件，并在修改它们时检索它们，以便我可以在我的 UI 中显示更改。 问题是我的函数不检索信息，只是返回默认值，如 null 或空字符串。

这是我的实体：

@Entity
data class Info(
    val email: String,
    val userName: String,
    @PrimaryKey(autoGenerate = true)
    val id: Int = 0,
)

这是我的道：

interface InfoDao {
    @Upsert
    suspend fun upsertInfo(info: Info)

    @Delete
    suspend fun deleteInfo(info: Info)

    @Query("SELECT userName FROM info LIMIT 1")
    fun getUsernameAsLiveData(): LiveData<String>

    @Query("SELECT email FROM info LIMIT 1")
    fun getEmailAsLiveData(): LiveData<String>
}

我的存储库：

class Repo(
    private val db: InfoDatabase,
) {
    fun openDatabase() {
        db.openHelper.writableDatabase
    }

    suspend fun upsertInfo(info: Info) {
        db.dao.upsertInfo(info)
    }

    suspend fun deleteInfo(info: Info) {
        db.dao.deleteInfo(info)
    }

    fun getUsername(): LiveData<String> {
        val usernameLiveData = db.dao.getUsernameAsLiveData()
        return usernameLiveData
    }

    fun getEmail(): LiveData<String> = db.dao.getEmailAsLiveData()
}

我的视图模型：

class RoomViewModel(
    private val repo: Repo,
) : ViewModel() {
    private val _isOpen = MutableStateFlow(false)
    val isOpen: StateFlow<Boolean> = _isOpen

    private val _usernameState = MutableLiveData<String?>()
    val usernameState: LiveData<String?> = _usernameState

    private val _emailState = MutableLiveData<String?>()
    val emailState: LiveData<String?> = _emailState

    fun openDatabase() {
        viewModelScope.launch {
            repo.openDatabase()
            _isOpen.value = true
        }
    }

    suspend fun fetchData() {
        viewModelScope.launch {
            if (!isOpen.value) {
                repo.openDatabase()
            }

            val username = repo.getUsername().value
            _usernameState.value = username

            val email = repo.getEmail().value
            _emailState.value = email
        }
    }

    suspend fun upsertInfo(info: Info) {
        viewModelScope.launch {
            repo.upsertInfo(info)
        }
    }
}

我的可组合项：

@Composable
fun DeviceScreen(
    navController: NavHostController,
    lifecycleOwner: LifecycleOwner,
    roomViewModel: RoomViewModel,
) {
    val username by roomViewModel.usernameState.observeAsState()
    val email by roomViewModel.emailState.observeAsState()

    LaunchedEffect(Unit) {
        roomViewModel.openDatabase() // before this my roomDatabase was closed
    }

    LaunchedEffect(roomViewModel.isOpen) {
        roomViewModel.fetchData()
    }
}

我原本希望在 logcat 中看到正常的电子邮件和用户名，也许是一个可以使用的列表，但我得到的只是 null 或空字符串。我到处都放了日志语句，试图找出问题所在。起初我以为是因为我的数据库在数据库检查器中关闭了，但我解决了这个问题，现在它已经打开了。我可以看到我创建的虚拟用户名和电子邮件，但仍然无法访问它们。我尝试过将其转换为流程或简单字符串，但没有成功。我完全没有主意了。

我从另一个应用程序复制粘贴的代码，它执行完全相同的操作并且有效。我的代码中的 log.i() 语句显示信息发生了变化，但我的谷歌地图可组合项不会使用从 viewModel.getRestaurantList() 收到的新列表重新组合。我发现唯一可疑的是按钮内的 Log.i() 始终为空，即使视图模型中的函数内的另一个 Log.i() 显示列表已由函数 getRestaurantList 更新视图模型。这是相关代码：

充当屏幕的可组合项：

@Composable
fun SearchScreen(
    myName: String,
    navController: NavController,
    context: Context = LocalContext.current,
) {
    val viewModel: LocationViewModel = LocationViewModel(context)
    var user: User = User(myName, 1, 0.0, 0.0)
    ...
}

搜索屏幕中的可组合项可以工作但不会更新（地图加载并且我可以导航，但是单击按钮后基于收到的列表的标记不会出现）：

ComposeMapDemo(
    restaurantList = viewModel.restaurantListResponse,
    myName,
    onMarkerClick = { marker, restaurant -> navController.navigate(route = ... },
)

调用函数更新餐厅列表的按钮：

Button(onClick = {
    //this log statement is always empty, no matter how often I click on the button
    Log.i("Tag", "restaurantList inside button" + viewModel.restaurantListResponse.toString())
    viewModel.getRestaurantList(restaurant)
}) {
    Text(text = "Scan")
}

视图模型：

class LocationViewModel(val context: Context) : ViewModel() {
    var restaurantListResponse: List<Restaurant> by mutableStateOf(listOf())

    fun getRestaurantList(restaurant: Restaurant) {
        viewModelScope.launch {
            try {
                restaurantListResponse = getRestaurantsListRequest(restaurant)
                //this Log.i shows that restaurantListResponse updates
                Log.i(
                    "Tag",
                    "inside the getRestaurantList function of viewmodel" + restaurantListResponse.toString()
                )
            } catch (e: Exception) {
                errorMessage = e.message.toString()
            }
        }
    }
}

谷歌地图可组合项的详细信息（我认为不相关）：

@Composable
fun ComposeMapDemo(
    restaurantList: List<Restaurant>,
    myName: String?,
    onMarkerClick: (Marker, restaurant) -> Boolean,
) {
    val currentOnMarkerClick by rememberUpdatedState(onMarkerClick)
    val cameraPositionState = rememberCameraPositionState()
    val markerState = rememberMarkerState()

    SideEffect {
        if (restaurantList.isEmpty()) return@SideEffect
        val restaurant = restaurantList[0]
        val lat = restaurant?.latitude ?: return@SideEffect
        val lng = restaurant?.longitude ?: return@SideEffect
        val latlng = LatLng(lat, lng)
        markerState.position = latlng
        cameraPositionState.position = CameraPosition.fromLatLngZoom(latlng, 500f)
    }

    GoogleMap(
        modifier = Modifier
            .fillMaxHeight(0.5F)
            .fillMaxWidth(0.75F),
        cameraPositionState = cameraPositionState
    ) {

        for (restaurant in restaurantList) {
            if (restaurant.open == false) {
                continue

            } else {
                Marker(
                    icon = BitmapDescriptorFactory
                        .defaultMarker(BitmapDescriptorFactory.HUE_AZURE),
                    state = MarkerState(restaurant.position),
                    title = "${restaurant.name}",
                    onClick = { currentOnMarkerClick(it, restaurant) },
                )
            }
        }
    }
}

我有这个帖子请求，在 kotlin Android Studio 中使用改造

@POST("/registerUser.php")
    suspend fun createPost(
        @Body user: User
    ):Response<User>

数据类 User 是

data class User(
    //val id: Int?,
    val username:String?,
    val address: String?
)

如果我检查用户的内容

val user = User("Kilo", "Old")
Log.d("TAG", "$user")
RetrofitInstance.api.createPost(user) <----- This makes the @POST

我明白了

User(username=Kilo, address=Old)

那么我在服务器端收到了什么？它将所有内容都转换为 json 还是只是传递 User(username=Kilo, address=Old)？