Question

(依次,我需要对上述两个问题进行某种综合(1 ,<2/a/a>,但Imartm 并不够合)。

我有一组日本宇宙航空研究开发机构的代表,如:

abstract class Representation {
  def marshalToXml(): String = {
    val context = JAXBContext.newInstance(this.getClass())
    val writer = new StringWriter
    context.createMarshaller.marshal(this, writer)
    writer.toString()
  }
}

class Order extends Representation {
  @BeanProperty
  var name: String = _
  ...
}
class Invoice extends Representation { ... }

我的问题是我的“施工者”方法:

def unmarshalFromJson(marshalledData: String): {{My Representation Subclass}} = {
  val mapper = new ObjectMapper()
  mapper.getDeserializationConfig().withAnnotationIntrospector(new JaxbAnnotationIntrospector())
  mapper.readValue(marshalledData, this.getClass())
}

def unmarshalFromXml(marshalledData: String): {{My Representation Subclass}} = {
  val context = JAXBContext.newInstance(this.getClass())
  val representation = context.createUnmarshaller().unmarshal(
    new StringReader(marshalledData)
  ).asInstanceOf[{{Type of My Representation Subclass}}]
  representation // Return the representation
}

具体来说,我可以指出,如何把这些不区分的方法以安全的方式和分国家的方式传给我的每一个班子,然后从Schala(希望有时只使用抽象的类型信息)。换言之,我要这样做:

val newOrder = Order.unmarshalFromJson(someJson)

更有雄心的是:

class Resource[R <: Representation] {
    getRepresentation(marshalledData: String): R = 
        {{R s Singleton}}.unmarshalFromXml(marshalledData)
}

就我的特殊 blocks脚石而言:

I can t figure out whether I should define my unmarshalFrom*() constructors once in the Representation class, or in a singleton Representation object - if the latter, I don t see how I can automatically inherit that down through the class hierarchy of Order, Invoice etc.

I can t get this.type (as per this answer) to work as a way of self-typing unmarshalFromJson() - I get a compile error type mismatch; found: ?0 where type ?0 required: Representation.this.type on the readValue() call
I can t figure out how to use the implicit Default[A] pattern (as per this answer) to work down my Representation class hierarchy to call the singleton unmarshalling constructors using type information only

I know this is a bit of a mammoth question touching on various different (but related) issues - any help gratefully received!

* A/63/150。

Answer 1

关键不是试图将这种方法推向上,而是把它作为参数。说明你所期望的类型,让哪类系统处理。我试图让那些读写略微读写法的无色职业。

val order = UnMarshalXml( xml ).toRepresentation[Order]

下面是一部可充分检验的法典。

abstract class Representation {
  def marshalToXml(): String = {
      val context = JAXBContext.newInstance(this.getClass)
      val writer = new StringWriter
      context.createMarshaller.marshal(this, writer)
      writer.toString
  }
}

@XmlRootElement
class Order extends Representation {
  @BeanProperty
  var name: String = _
}

case class UnMarshalXml( xml: String ) {
  def toRepresentation[T <: Representation](implicit m:Manifest[T]): T = {
    JAXBContext.newInstance(m.erasure).createUnmarshaller().unmarshal(
      new StringReader(xml)
    ).asInstanceOf[T]
  }
}

object test {
  def main( args: Array[String] ) {
    val order = new Order
    order.name = "my order"
    val xml = order.marshalToXml()
    println("marshalled: " + xml )
    val received = UnMarshalXml( xml ).toRepresentation[Order]
    println("received order named: " + received.getName )
  }
}

如果你进行试验,你应看到以下产出。主要活动

marshalled: <?xml version="1.0" encoding="UTF-8" standalone="yes"?><order><name>my order</name></order>
received name: my order

Answer 2

这里是我用来支持第二个使用案例的尼尔斯法典最新版本,以及第一个版本:

case class UnmarshalXml(xml: String) {

  def toRepresentation[T <: Representation](implicit m: Manifest[T]): T =
    toRepresentation[T](m.erasure.asInstanceOf[Class[T]])

  def toRepresentation[T <: Representation](typeT: Class[T]): T =
    JAXBContext.newInstance(typeT).createUnmarshaller().unmarshal(
      new StringReader(xml)
    ).asInstanceOf[T]
}

这支持简单的例子:

val order = UnmarshalXml(xml).toRepresentation[Order]

但是,对于抽象的类型使用,你也可以这样做:

val order = UnmarshalXml(xml).toRepresentation[T](typeOfT)

(如果您在发布<条码>时使用另一条<条码>简单明了/条码>。

友情链接