问将DynamoDB专用JSON文本转换为普通JSON

EN

// convert dynamodb json map to normal json map
@Suppress("unchecked_cast")
internal fun Map<String, Any>.toSimpleMapValue(): Map<String, Any> {
    return this.mapValues { (_, v) ->
        (v as Map<String, Any>).toSimpleValue()
    }
}

@Suppress("unchecked_cast", "implicit_cast_to_any")
private fun Map<String, Any>.toSimpleValue() : Any {
    require(this.size == 1)

    val list = this.map { (k, v) ->
         when (k) {
            "BOOL" -> when (v) {
                0 -> false
                1 -> true
                else -> throw IllegalArgumentException("Unknown value $v for boolean")
            }
            "S" -> v as String
            "N" -> BigDecimal(v as String)
            "B" -> copyAllBytesFrom(v as ByteBuffer)
            "SS" -> LinkedHashSet(v as List<String>)
            "NS" -> LinkedHashSet((v as List<String>).map { BigDecimal(it) })
            "BS" -> LinkedHashSet((v as List<ByteBuffer>).map { copyAllBytesFrom(it) })
            "L" -> ArrayList((v as List<Any>).map { (it as Map<String, Any>).toSimpleValue() })
            "M" -> (v as Map<String, Any>).toSimpleMapValue()

            else -> throw IllegalArgumentException("Invalid key $k")
        }
    }

    return list[0]
}