RestController中的Spring SCALA返回列表

Question

How can I return a SCALA list or sequence in Sprint @RestController. List return value is not being serialized properly.

The result is:

[GET] http://localhost:9090/devices

{"empty":false,"traversableAgain":true}

Do I need to import Jackson ObjectMapper com.fasterxml.jackson for proper REST get result serialization on a list?

My RestController looks like this:

@RestController
class DeviceController {

  var devices = Set[Device]()

  @RequestMapping(value = Array("/devices"), method = Array(RequestMethod.GET))
  def accounts() : List[Device] =  devices.toList
}

Answer 1

Spring was NOT designed with SCALA in mind - hence it cannot handle SCALA lists properly. Nor can it handle Seq[Device].

Just use SCALA's JavaConvertes package to easliy convert SCALA list to JAVA list.

import scala.collection.JavaConverters._

@RestController
class DeviceController {

  var devices = Set[Device]()

  @RequestMapping(value = Array("/devices"), method = Array(RequestMethod.GET))
  def accounts() : java.util.List[Device] =  {
    devices.toList.asJava
  }
}

and the result will be:

[GET] http://localhost:9090/devices
[{"name":"first device"},{"name":"second device"}]

Remember to change the result type to: java.util.List[Device]