给定同构类型对象流,我如何将它们序列化为二进制,将它们写入磁盘,从磁盘读取它们,然后使用 Scala Pickling 反序列化它们?
例如:
object PicklingIteratorExample extends App {
import scala.pickling.Defaults._
import scala.pickling.binary._
import scala.pickling.static._
case class Person(name: String, age: Int)
val personsIt = Iterator.from(0).take(10).map(i => Person(i.toString, i))
val pklsIt = personsIt.map(_.pickle)
??? // Write to disk
val readIt: Iterator[Person] = ??? // Read from disk and unpickle
}
最佳答案
我找到了一种方法来处理标准文件:
object PickleIOExample extends App {
import scala.pickling.Defaults._
import scala.pickling.binary._
import scala.pickling.static._
val tempPath = File.createTempFile("pickling", ".gz").getAbsolutePath
val outputStream = new FileOutputStream(tempPath)
val inputStream = new FileInputStream(tempPath)
val persons = for{
i <- 1 to 100
} yield Person(i.toString, i)
val output = new StreamOutput(outputStream)
persons.foreach(_.pickleTo(output))
outputStream.close()
val personsIt = new Iterator[Person]{
val streamPickle = BinaryPickle(inputStream)
override def hasNext: Boolean = inputStream.available > 0
override def next(): Person = streamPickle.unpickle[Person]
}
println(personsIt.mkString(", "))
inputStream.close()
}
但我仍然无法找到适用于 gzip 压缩文件的解决方案。由于我不知道如何检测EOF?由于 GZIPInputStream 可用方法不指示 EOF,因此以下抛出 EOF 异常:
object PickleIOExample extends App {
import scala.pickling.Defaults._
import scala.pickling.binary._
import scala.pickling.static._
val tempPath = File.createTempFile("pickling", ".gz").getAbsolutePath
val outputStream = new GZIPOutputStream(new FileOutputStream(tempPath))
val inputStream = new GZIPInputStream(new FileInputStream(tempPath))
val persons = for{
i <- 1 to 100
} yield Person(i.toString, i)
val output = new StreamOutput(outputStream)
persons.foreach(_.pickleTo(output))
outputStream.close()
val personsIt = new Iterator[Person]{
val streamPickle = BinaryPickle(inputStream)
override def hasNext: Boolean = inputStream.available > 0
override def next(): Person = streamPickle.unpickle[Person]
}
println(personsIt.mkString(", "))
inputStream.close()
}
关于scala - 使用 Pickling 序列化到磁盘并反序列化 Scala 对象,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/30709896/