创建跨时区同步倒计时器的Android教程

import java.time.LocalDateTime
import java.time.ZoneId
import java.time.ZonedDateTime
import java.time.format.DateTimeFormatter
import java.util.Date
import java.util.Locale

fun countdownTimer(endDate: Date): Long {
    // 1. 定义 PST 时区
    val pstZoneId = ZoneId.of("America/Los_Angeles")

    // 2. 获取当前时间，并转换为 PST 时区
    val now = LocalDateTime.now(ZoneId.systemDefault()) //获取当前设备所在时区时间
    val nowInPST: ZonedDateTime = now.atZone(pstZoneId)

    // 3. 将结束时间转换为 PST 时区
    val endDateInPST: ZonedDateTime = endDate.toInstant().atZone(pstZoneId)

    // 4. 计算剩余时间（毫秒）
    return endDateInPST.toInstant().toEpochMilli() - nowInPST.toInstant().toEpochMilli()
}

fun formatCountdown(millisUntilFinished: Long): String {
    val seconds = (millisUntilFinished / 1000).toInt() % 60
    val minutes = (millisUntilFinished / (1000 * 60) % 60).toInt()
    val hours = (millisUntilFinished / (1000 * 60 * 60) % 24).toInt()
    val days = (millisUntilFinished / (1000 * 60 * 60 * 24)).toInt()

    return String.format(Locale.getDefault(), "%d days, %02d hours, %02d minutes, %02d seconds", days, hours, minutes, seconds)
}

// 示例用法
fun main() {
    // 假设从服务器获取的结束时间 (Date 对象)
    val endDateString = "Wed Nov 30 12:00:00 PST 2022"
    val formatter = DateTimeFormatter.ofPattern("EEE MMM dd HH:mm:ss z yyyy", Locale.US)
    val zonedDateTime = ZonedDateTime.parse(endDateString, formatter)
    val endDate = Date.from(zonedDateTime.toInstant()) // Convert ZonedDateTime to Date

    val remainingTimeMillis = countdownTimer(endDate)
    val formattedTime = formatCountdown(remainingTimeMillis)
    println("Remaining time: $formattedTime")
}