使用gson，你可以编写自己的json阅读器：

With gson, you could write your own json reader:

case class Customer(id: Int, name: String, address: Option[String], 
  city: Option[String], state: Option[String], user_id: Int)

object CustomerJsonReader {

   def read(in: Reader) = readCustomers(new JsonReader(in))

   def readCustomers(reader: JsonReader) = {
     val customers = new ListBuffer[Customer]
     reader.beginArray()
     while (reader.hasNext()) {
       customers += readCustomer(reader)
     }
     reader.endArray()
     customers toList
   }

   def readCustomer(reader: JsonReader): Customer = {
     var id = 0
     var customerName = ""
     var address: Option[String] = None
     var city: Option[String] = None
     var state: Option[String] = None
     var userId = 0

     reader.beginObject()
     while (reader.hasNext()) {
       val name = reader.nextName()
       name match {
         case "id" => id = reader.nextInt()
         case "address" => address = Some(reader.nextString())
         case "state" => state = Some(reader.nextString())
         case "user_id" => userId = reader.nextInt()
         case "name" => customerName = reader.nextString()
         case "city" => city = Some(reader.nextString())
         case _ => reader.skipValue()
       }
     }
     reader.endObject()
     Customer(id, customerName, address, city, state, userId)
   }

}

val json = 
  """
  [{"name":"Cool","city":"College Park","address":"806","id":1},
  {"name":"Mars ","city":"Durham","address":"12","id":2},
  {"name":"Something","city":"Raleigh  ","address":"","id":3},
  {"name":"test","city":"","address":"","id":5}] 
  """

val customers: List[Customer] = 
  CustomerJsonReader.read(new StringReader(json))