Android开发：基于 Kotlin 协程的设备指令控制工具类设计与实现

在安卓开发中，设备控制是一个常见的需求。本文将介绍如何使用 Kotlin 协程实现一个高效、健壮的设备指令控制工具类。该工具类支持指令队列、重试机制、状态管理等功能，并适配安卓平台，确保生命周期管理和主线程安全性。通过本文，你将学习到如何设计一个可扩展的工具类，并将其集成到安卓项目中。

库引入

在 build.gradle 文件中添加以下依赖：

dependencies {implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.6.0" // Kotlin 协程implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.6.0" // 安卓协程支持implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.4.1" // ViewModel 支持implementation "androidx.lifecycle:lifecycle-runtime-ktx:2.4.1" // Lifecycle 支持
}

完整代码

1. 工具类代码

import kotlinx.coroutines.*
import kotlinx.coroutines.channels.Channel
import kotlinx.coroutines.flow.MutableSharedFlow
import kotlinx.coroutines.flow.asSharedFlow/*** 指令发送工具类（适配安卓平台）** @param sendCommand 发送指令的函数，返回指令是否成功* @param config 工具类配置*/
class CommandSender(private val sendCommand: suspend (Command) -> Response,private val config: CommandSenderConfig = CommandSenderConfig()
) {// 指令队列private val commandChannel = Channel<Command>(capacity = Channel.UNLIMITED)// 指令状态流private val _commandStateFlow = MutableSharedFlow<CommandState>(replay = 1)val commandStateFlow = _commandStateFlow.asSharedFlow()// 协程作用域（使用 SupervisorJob）private val scope = CoroutineScope(config.dispatcher + SupervisorJob())// 是否正在运行private var isRunning = trueinit {// 启动指令处理协程scope.launch {for (command in commandChannel) {if (!isRunning) break // 如果工具类已关闭，停止处理sendCommandWithRetry(command)}}}/*** 添加指令到队列*/fun addCommand(command: Command) {if (!isRunning) throw IllegalStateException("CommandSender is already closed")scope.launch {commandChannel.send(command)}}/*** 发送指令并重试*/private suspend fun sendCommandWithRetry(command: Command, retryCount: Int = 0, currentDelay: Long = config.retryDelay) {log("Sending command: ${command.id}, retryCount: $retryCount")val response = try {sendCommand(command)} catch (e: Exception) {log("Command ${command.id} failed with exception: ${e.message}")Response(command.id, false)}if (response.isSuccess) {log("Command ${command.id} succeeded")_commandStateFlow.emit(CommandState.Success(command))} else if (retryCount < config.maxRetries - 1) {log("Retrying command: ${command.id}")delay(currentDelay)sendCommandWithRetry(command, retryCount + 1, currentDelay * 2) // 指数退避} else {log("Command ${command.id} failed after ${config.maxRetries} retries")_commandStateFlow.emit(CommandState.Failed(command))}}/*** 清理资源*/fun cleanup() {isRunning = falsescope.cancel("CommandSender is shutting down")commandChannel.close()log("CommandSender resources cleaned up")}/*** 日志记录*/private fun log(message: String) {println("CommandSender: $message") // 替换为实际日志工具}
}/*** 工具类配置*/
data class CommandSenderConfig(val maxRetries: Int = 3,val retryDelay: Long = 300,val dispatcher: CoroutineDispatcher = Dispatchers.IO
)/*** 指令数据类*/
data class Command(val id: String, val data: String, val priority: Int = 0)/*** 指令响应数据类*/
data class Response(val commandId: String, val isSuccess: Boolean)/*** 指令状态密封类*/
sealed class CommandState {data class Pending(val command: Command, val retryCount: Int = 0) : CommandState()data class Success(val command: Command) : CommandState()data class Failed(val command: Command, val error: Throwable? = null) : CommandState()data class Timeout(val command: Command) : CommandState()data class Cancelled(val command: Command) : CommandState()
}

2. 在 `ViewModel` 中使用工具类

import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import kotlinx.coroutines.flow.SharedFlow
import kotlinx.coroutines.launchclass DeviceControlViewModel : ViewModel() {// 创建 CommandSender 实例private val commandSender = CommandSender(sendCommand = { command ->// 模拟发送指令并接收回码delay(100) // 模拟网络延迟Response(command.id, Math.random() > 0.5) // 随机返回成功或失败})// 暴露指令状态流val commandStateFlow: SharedFlow<CommandState> = commandSender.commandStateFlow/*** 添加指令*/fun addCommand(command: Command) {viewModelScope.launch {commandSender.addCommand(command)}}/*** 清理资源*/override fun onCleared() {super.onCleared()commandSender.cleanup()}
}

3. 在 `Activity` 或 `Fragment` 中观察状态

import android.os.Bundle
import androidx.activity.viewModels
import androidx.appcompat.app.AppCompatActivity
import androidx.lifecycle.lifecycleScope
import kotlinx.coroutines.flow.collectclass DeviceControlActivity : AppCompatActivity() {private val viewModel: DeviceControlViewModel by viewModels()override fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)// 监听指令状态lifecycleScope.launch {viewModel.commandStateFlow.collect { state ->when (state) {is CommandState.Success -> {// 更新 UI：指令成功println("Command ${state.command.id} succeeded")}is CommandState.Failed -> {// 更新 UI：指令失败println("Command ${state.command.id} failed")}else -> {}}}}// 添加指令viewModel.addCommand(Command("1", "Turn on"))viewModel.addCommand(Command("2", "Turn off"))}
}