我的应用程序正在后台检查未读电子邮件，问题是我需要在上次检查电子邮件时保存和检索 lastCheckedDate，以便我只能显示新收到的电子邮件。
为了从数据存储中检索数据，我使用 observeLastCheckedDate() 并且我必须使用处理程序调用它，因为如果我没有得到：
java.lang.IllegalStateException：无法在后台线程上调用观察
函数 observeLastCheckedDate() 被调用，但是当它完成时（更新 lastCheckedDate），workManager 任务已经完成了未更新的 var lastchecked 日期。
在主类中，我通过创建和调用回调来避免这个问题，但在这里不起作用（它使整个应用程序冻结），所以我们需要等待该函数完成或获取一些从数据存储中检索数据的新方法。
class WorkerMan(private val mContext: Context, workerParameters: WorkerParameters) :
CoroutineWorker(mContext, workerParameters) {
private lateinit var settingsManager: SettingsManager
var lastCheckedDate: Long = 0
@SuppressLint("RestrictedApi", "CheckResult")
val email = inputData.getString("email")
val password = inputData.getString("password")
val token = inputData.getString("token")
fun saveLastCheckedDate(lastCheckedDate: Long) {
GlobalScope.launch {
settingsManager.storeLastCheckedDate(lastCheckedDate)
}
}
private fun observeLastCheckedDate() {
settingsManager.lastCheckedDateFlow.asLiveData().observe(
ProcessLifecycleOwner.get(),
{
lastCheckedDate = it
println("LASTCHECKEDDATE LOADED")
}
)
}
@SuppressLint("RestrictedApi", "WrongThread")
override suspend fun doWork(): Result {
withContext(Dispatchers.IO) {
settingsManager = SettingsManager(getApplicationContext())
var messageCounter = 0;
val handler = Handler(Looper.getMainLooper())
handler.post {
observeLastCheckedDate()
}
println("**************************************************************************")
println("**************************************************************************")
println("WorkManager: Work called")
println("WorkManager email: " + email)
println("WorkManager: Last Checked Moment : " + lastCheckedDate.toString())
println("WorkManager: Current Moment : " + Instant.now().toEpochMilli())
println("**************************************************************************")
println("**************************************************************************")
try {
val session = Session.getDefaultInstance(Properties())
val store = session.getStore("imaps")
store.connect(
"mail.metropolitan.ac.rs",
993,
email,
password
)
val inbox = store.getFolder("INBOX")
inbox.open(Folder.READ_ONLY)
val messages = inbox.search(
FlagTerm(Flags(Flags.Flag.SEEN), false)
)
Arrays.sort(
messages
) { m1: Message, m2: Message ->
try {
return@sort m2.sentDate.compareTo(m1.sentDate)
} catch (e: MessagingException) {
throw RuntimeException(e)
}
}
// println("- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ")
// println("WorkManager Started")
// println("WorkMananager email: " + email)
// val current = LocalTime.now()
// println("WorkMananager time: " + current)
// println("Messages amount: " + messages.size)
// println("- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ")
for (message in messages) {
Thread.sleep(1000)
messageCounter++
if (message.receivedDate.toInstant().toEpochMilli() >= lastCheckedDate) {
Thread.sleep(1000)
println("=====================================================")
println("NOTIFIKACIJA")
var title = ""
for (element in message.from) {
title += element.toString().substringAfter("<").substringBefore(">")
title += " "
}
println("Title :" + title)
println("Subject :" + message.subject)
println("Datum i vreme : " + message.receivedDate)
title.replace("[", "")
title.replace("]", "")
send(token, message.subject, title)
}
if (messageCounter > 10) {
break
}
}
saveLastCheckedDate(Instant.now().toEpochMilli())
println("=====================================================")
Log.d("WorkManager", "Job finished")
} catch (e: Exception) {
Log.d("WorkManager error", "doWork not executed")
Log.d("WorkManager error", "error: ")
Log.d("WorkManager error", e.printStackTrace().toString())
} catch (e: NetworkOnMainThreadException) {
Log.d("WorkManager error", "doWork not executed")
Log.d("WorkManager error", "NetworkOnMainThreadException: ")
Log.d("WorkManager error", e.toString())
}
}
return Result.Success();
}
}
fun send(to: String?, body: String?, title: String?): String? {
try {
val apiKey =
"***************************************"
val url = URL("https://fcm.googleapis.com/fcm/send")
val conn = url.openConnection() as HttpURLConnection
conn.doOutput = true
conn.requestMethod = "POST"
conn.setRequestProperty("Content-Type", "application/json")
conn.setRequestProperty("Authorization", "key=$apiKey")
conn.doOutput = true
val message = JSONObject()
message.put("to", to)
message.put("priority", "high")
val notification = JSONObject()
notification.put("title", title)
notification.put("body", body)
message.put("notification", notification)
val os = conn.outputStream
os.write(message.toString().toByteArray())
os.flush()
os.close()
val responseCode = conn.responseCode
println("\nSending 'POST' request to URL : $url")
println("Post parameters : $message")
println("Response Code : $responseCode")
println("Response Code : " + conn.responseMessage)
val `in` = BufferedReader(InputStreamReader(conn.inputStream))
var inputLine: String?
val response = StringBuffer()
while (`in`.readLine().also { inputLine = it } != null) {
response.append(inputLine)
}
`in`.close()
println(response.toString())
return response.toString()
} catch (e: Exception) {
Log.d("WorkManager error", "send not executed")
Log.d("WorkManager error", "error: ")
Log.d("WorkManager error", e.printStackTrace().toString())
} catch (e: NetworkOnMainThreadException) {
Log.d("WorkManager error", "send() not executed")
Log.d("WorkManager error", "NetworkOnMainThreadException: ")
Log.d("WorkManager error", e.toString())
}
return "error"
}
数据存储类：
class SettingsManager(context: Context) {
private val dataStore = context.createDataStore(name = "user_settings_preferencess")
companion object {
val ENABLE_NOTIFICATIONS = preferencesKey<Int>("ENABLE_NOTIFICATIONS")
val ENABLE_MAIL_NOTIFICATIONS = preferencesKey<Int>("ENABLE_MAIL_NOTIFICATIONS")
val LAST_CHECKED_DATE = preferencesKey<Long>("LAST_CHECKED_DATE")
}
//Store user data
suspend fun storeNotifications(enableNotifications: Int) {
dataStore.edit {
it[ENABLE_NOTIFICATIONS] = enableNotifications
}
}
suspend fun storeMailNotifications(enableMailNotifications: Int) {
dataStore.edit {
it[ENABLE_MAIL_NOTIFICATIONS] = enableMailNotifications
}
}
suspend fun storeLastCheckedDate(lastCheckedDate: Long) {
dataStore.edit {
it[LAST_CHECKED_DATE] = lastCheckedDate
}
}
val lastCheckedDateFlow: Flow<Long> = dataStore.data.map {
it[LAST_CHECKED_DATE] ?: 0
}
val enableNotificationsFlow: Flow<Int> = dataStore.data.map {
it[ENABLE_NOTIFICATIONS] ?: 1
}
val enableMailNotificationsFlow: Flow<Int> = dataStore.data.map {
it[ENABLE_MAIL_NOTIFICATIONS] ?: 1
}
}