基于Kotlin Multiplatform实现静态文件服务器（四）

Android前台服务

Android前台服务用于执行用户可察觉的操作。

前台服务显示状态栏通知，让用户知道您的 应用正在前台执行任务并消耗系统资源。

文件服务启动和停止

在JVM上，通过守护线程来启动文件服务。

class DesktopServerViewModel : ServerViewModel, ViewModel() {...override fun startFileServer(httpServerConfig: HttpFileServerConfig?) {startServerDaemon(httpServerConfig)}override fun stopFileServer() {stopServerDaemon()}
}actual fun getMsgViewModel(): ServerViewModel = DesktopServerViewModel()

class ServerDaemon(private val httpServerConfig: HttpFileServerConfig) : Thread() {override fun run() {bootStrapServer.startServer(httpServerConfig)}companion object {private lateinit var serverDaemon: ServerDaemonfun startServerDaemon(httpServerConfig: HttpFileServerConfig?) {httpServerConfig ?: run {LogTool.e("不能加载配置文件")return}serverDaemon = ServerDaemon(httpServerConfig).also {it.isDaemon = trueit.name = "Server-daemon-thread"}.apply {start()}}fun stopServerDaemon() {try {bootStrapServer.stopServer()if (serverDaemon.isAlive) {serverDaemon.interrupt()}} catch (e: InterruptedException) {e.printStackTrace()}}}
}

在Android中，为了避免由于界面退出或锁屏后被系统杀死进程导致文件服务中断，使用前台服务实现。

@Suppress("DEPRECATION")
class AndroidServerViewModel : ViewModel(), ServerViewModel {...@RequiresApi(VERSION_CODES.O)override fun startFileServer(httpServerConfig: HttpFileServerConfig?) {FileServerApp.app.startForegroundService(fileServerIntent.also { //启动前台服务it.putExtra("serverPort", httpServerConfig?.serverPort)it.putExtra("fileDirectory", httpServerConfig?.fileDirectory)})}override fun stopFileServer() {FileServerApp.app.stopService(fileServerIntent) // 停止前台服务。}...private companion object {...val fileServerIntent = Intent().also {it.setClass(FileServerApp.app.applicationContext, FileServerService::class.java)}}
}actual fun getMsgViewModel(): ServerViewModel = AndroidServerViewModel()

创建FileServerService，并声明为前台服务。声明前台服务，需要在AndroidManifest.xml中声明，并申请权限。 权限相关可参阅https://blog.csdn.net/luckyion/article/details/141305213

class FileServerService : Service() {override fun onBind(intent: Intent): IBinder? = null@RequiresApi(Build.VERSION_CODES.O)override fun onCreate() {super.onCreate()getSystemService(NotificationManager::class.java).apply {if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {createNotificationChannel(NotificationChannel(MY_CHANNEL_ID,MY_CHANNEL_NAME,NotificationManager.IMPORTANCE_HIGH))}}try {startForeground(MY_NOTIFICATION_ID, getNotification(this))LogTool.i("startForeground")} catch (e: Exception) {e.printStackTrace()}}override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {LogTool.i("onStartCommand")startServer(HttpFileServerConfig(intent?.getIntExtra("serverPort", 80)!!,intent.getStringExtra("fileDirectory")!!))return super.onStartCommand(intent, flags, startId)}private fun startServer(httpServerConfig: HttpFileServerConfig) {LogTool.i("startServer")startServerDaemon(httpServerConfig) // 启动文件服务线程}private fun stopServer() {stopServerDaemon()  // 停止文件服务线程}override fun onDestroy() {stopServer()super.onDestroy()}@RequiresApi(Build.VERSION_CODES.O)private fun getNotification(context: Context) = // 前台服务通知，创建前台服务，必须发送一个通知。Notification.Builder(context, MY_CHANNEL_ID).setShowWhen(true).setSmallIcon(R.drawable.explore).setContentTitle("服务服务器").setContentText("服务已启动").also {if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {it.setChannelId(MY_CHANNEL_ID)}}.build()private companion object {private const val MY_CHANNEL_ID = "File-server-foreground-service-channel"private const val MY_CHANNEL_NAME = "File-server-foreground-service-channel-name"private const val MY_NOTIFICATION_ID = 10086}
}