Scala嵌套对象序列化

Question

Hi I have a case class A which contains variables pointing to another class B (with companion object, which has variables pointing to yet another class C which also has companion object). class B and C are from other libraries. What is the easier way that I could serialize my case class A?

case class A() {
  val b = B
}

//B & C are defined in a library that I have no control of
object B {
  val c = C
} 

class B{
  ...
}

object C{
  ...
}  

class C{
  ...
}

Answer 1

If these classes are already Serializable , you don't need to do anything special, so the rest of the answer assumes they aren't.

If these fields can be reconstructed from others, mark them as @transient and implement readObject (as described in http://docs.oracle.com/javase/8/docs/api/java/io/Serializable.html ) to restore them. Unfortunately, you can't initialize val s in readObject and will have to write something like

case class A() {
  private var _b = B
  def b = _b
}

If they can't, you need to store something they can be restored from in writeObject as well.

Finally, you can use one of the third-party serialization libraries like Kryo or Scala Pickling , because basically all of them allow to add support for types not under your control (otherwise they couldn't work with the types in standard Java library!)