Time 如何将UNIX时间戳转换为Kotlin中的UInt8数组？

我需要将UNIX时间戳转换为Kotlin中的

ByteArray

。问题是，当我使用下面的代码执行此操作时，我会得到一个类似于

C1F38E05

（hex）的结果，它远远高于当前的历元时间

internal fun Int.toByteArray(): ByteArray {
    return byteArrayOf(
            this.ushr(24).toByte(),
            this.ushr(16).toByte(),
            this.ushr(8).toByte(),
            this.toByte()
    )
}

val timeUTC = System.currentTimeMillis().toInt().toByteArray()

---

正确的方法是什么？

系统。currentTimeMillis（）

返回一个

Long

，因此必须为

Long

实现

toByteArray

，如下所示：

fun Long.toByteArray(): ByteArray {                     
    val result = ByteArray(8)                           
    result[7] = (this and 0xFF).toByte()                
    result[6] = ((this ushr 8) and 0xFF).toByte()       
    result[5] = ((this ushr 16) and 0xFF).toByte()      
    result[4] = ((this ushr 24) and 0xFF).toByte()      
    result[3] = ((this ushr 32) and 0xFF).toByte()      
    result[2] = ((this ushr 40) and 0xFF).toByte()      
    result[1] = ((this ushr 48) and 0xFF).toByte()      
    result[0] = ((this ushr 56) and 0xFF).toByte()      
    return result                                       
}    

如果无符号字节需要此选项，请使用：

fun Long.toByteArray(): UByteArray {
    val result = UByteArray(8)
    result[7] = (this and 0xFF).toUByte()
    result[6] = ((this ushr 8) and 0xFF).toUByte()
    result[5] = ((this ushr 16) and 0xFF).toUByte()
    result[4] = ((this ushr 24) and 0xFF).toUByte()
    result[3] = ((this ushr 32) and 0xFF).toUByte()
    result[2] = ((this ushr 40) and 0xFF).toUByte()
    result[1] = ((this ushr 48) and 0xFF).toUByte()
    result[0] = ((this ushr 56) and 0xFF).toUByte()
    return result
}

这可以像以下示例中那样使用：

fun main() {
    val timeUTC = System.currentTimeMillis().toByteArray()    
    println(timeUTC.map { byte -> byte.toString(16).toUpperCase() }.joinToString(""))
}

---

如果需要32位值，则需要将时间转换为秒

fun Int.toByteArray() = byteArrayOf(
    this.toByte(),
    (this ushr 8).toByte(),
    (this ushr 16).toByte(),
    (this ushr 24).toByte()
)

val timeUTC = (System.currentTimeMillis() / 1000).toInt().toByteArray()

---

和0xFF

有什么意义？在强制转换为字节时，最左边的位将被截断。