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akka http使用json支持和xmlsupport

akka-http scala

6

coder25 · 技术社区 · 8 年前

我希望在部门为“HR”时以XML格式打印数据,而在部门为“Tech”时以JSON格式打印数据。

我们能用吗喷雾JSON载体 https://doc.akka.io/docs/akka-http/current/common/json-support.html 和XML支持 https://doc.akka.io/docs/akka-http/current/common/xml-support.html 在一起

 private[rest] def route =
  (pathPrefix("employee") & get) {
    path(Segment) { id =>
      parameters('department ? "") { (flag) =>
        extractUri { uri =>
          complete {
            flag match {
              case "hr": =>  {

            HttpEntity(MediaTypes.`application/xml`.withCharset(HttpCharsets.`UTF-8`),"hr department")
            }
              case "tech" =>{
                HttpEntity(ContentType(MediaTypes.`application/json`), mapper.writeValueAsString("tech department"))

              }

            }
          }
        }
      }
    }
  }

我尝试的解决方案我通过使用jsonProtocols和scalaxmlsupport尝试了下面的方法。我得到了预期的编译错误,但找到了部门。

case class department(name:String)
private[rest] def route =
  (pathPrefix("employee") & get) {
    path(Segment) { id =>
      parameters('department ? "") { (flag) =>
        extractUri { uri =>
          complete {
            flag match {
              case "hr": =>  {

            complete(department(name =flag))
            }
              case "tech" =>{
                complete(department(name =flag))

              }

            }
          }
        }
      }
    }
  }

2 回复 | 直到 8 年前

1

3

SergGr 8 年前

我认为要达到你想要的目标,你必须克服几个问题:

您希望根据请求参数自定义响应类型。它意味着标准 implicit -基于封送对您不起作用,您必须执行一些明确的步骤。
您希望将一些业务对象封送到XML字符串中。不幸的是, ScalaXmlSupport 您引用的不支持这种情况,它只能将XML树封送到响应中。所以您需要一些可以进行XML序列化的库。一种选择是使用 jackson-dataformat-xml 具有 jackson-module-scala . 这也意味着你必须写下你自己的习惯 Marshaller . 幸运的是,这并不难。

下面是一些可能适用于您的简单代码:

import akka.http.scaladsl.marshalling.{ToResponseMarshallable, Marshaller}

// json marshalling
import akka.http.scaladsl.marshallers.sprayjson.SprayJsonSupport
import spray.json._
import spray.json.DefaultJsonProtocol._
implicit val departmentFormat = DefaultJsonProtocol.jsonFormat1(department)
val departmentJsonMarshaller = SprayJsonSupport.sprayJsonMarshaller[department]

// xml marshalling, need to write a custom Marshaller
// there are several MediaTypes for XML such as `application/xml` and `text/xml`, you'll have to choose the one you need.
val departmentXmlMarshaller = Marshaller.StringMarshaller.wrap(MediaTypes.`application/xml`)((d: department) => {
  import com.fasterxml.jackson.dataformat.xml.XmlMapper
  import com.fasterxml.jackson.module.scala.DefaultScalaModule
  val mapper = new XmlMapper()
  mapper.registerModule(DefaultScalaModule)
  mapper.writeValueAsString(d)
})


private val route =
  (pathPrefix("employee") & get) {
    path(Segment) { id =>
      parameters('department ? "") { (flag) =>
        extractUri { uri => {
          flag match {
            case "hr" => {
              // explicitly use the XML marshaller 
              complete(ToResponseMarshallable(department(name = flag))(departmentXmlMarshaller))
            }
            case "tech" => {
              // explicitly use the JSON marshaller 
              complete(ToResponseMarshallable(department(name = flag))(departmentJsonMarshaller))
            }
          }
        }
        }
      }
    }
  }

请注意,为了使Jackson XML序列化程序正确工作, department 类应该是顶级类,否则您会得到一个关于错误根名称的神秘错误。

2

1

kag0 8 年前

Akka HTTP已经内置了内容类型协商。理想情况下,您应该使用这个方法,让一个marshaller知道如何将您的部门转换为XML或JSON,并让客户机设置 Accept 标题。

不过,听起来可能你不能让你的客户这样做,所以这里是你可以做的,假设你已经 ToEntityMarshaller[department] 对于XML和JSON,使用 ScalaXmlSupport 和 SprayJsonSupport .

val toXmlEntityMarshaller: ToEntityMarshaller[department] = ???
val toJsonEntityMarshaller: ToEntityMarshaller[department] = ???
implicit val departmentMarshaller = Marshaller.oneOf(toJsonEntityMarshaller, toXmlEntityMarshaller)

def route =
  parameters("department") { departmentName =>
    // capture the Accept header in case the client did request one
    optionalHeaderValueByType[Accept] { maybeAcceptHeader => 
      mapRequest ( _
        .removeHeader(Accept.name)
        // set the Accept header based on the department
        .addHeader(maybeAcceptHeader.getOrElse(
          Accept(departmentName match {
            case "hr" â MediaTypes.`application/xml`
            case "tech" â MediaTypes.`application/json`
          })
        ))
      ) (
        // none of our logic code is concerned with the response type
        complete(department(departmentName))
        )
    }
  }