如何使用使用playframework库的Scala独立应用程序

Question

我有这个简单的测试Scala应用程序,它阻止http请求:

build.sbt

name := "hello"

version := "1.0"

scalaVersion := "2.11.2"

libraryDependencies += "com.typesafe.play" %% "play-ws" % "2.4.0-M1"

Test.scala

import play.api.libs.json._
import play.api.libs.ws._
import scala.concurrent.duration.Duration
import scala.concurrent.{Await, Future}

object Test {
  def main(args: Array[String]) = {
    val wsClient = WS.client
    val body = getBody(wsClient.url("http://example.com/").get())
    println(s"body: $body")
  }

  def getBody(future: Future[WSResponse]) = {
    val response = Await.result(future, Duration.Inf);
    if (response.status != 200)
      throw new Exception(response.statusText);
    response.body
  }
}

此应用程序失败:

Exception in thread "main" java.lang.RuntimeException: There is no started application

如何解决这个问题？

Answer 1

编辑Play 2.5:

import akka.actor.ActorSystem
import akka.stream.ActorMaterializer
import play.api.libs.ws._
import play.api.libs.ws.ahc.AhcWSClient

import scala.concurrent.Future

object Main {
  import scala.concurrent.ExecutionContext.Implicits._

  def main(args: Array[String]): Unit = {
    implicit val system = ActorSystem()
    implicit val materializer = ActorMaterializer()
    val wsClient = AhcWSClient()

    call(wsClient)
      .andThen { case _ => wsClient.close() }
      .andThen { case _ => system.terminate() }
  }

  def call(wsClient: WSClient): Future[Unit] = {
    wsClient.url("http://www.google.com").get().map { response =>
      val statusText: String = response.statusText
      println(s"Got a response $statusText")
    }
  }
}

请参阅:

• https://www.playframework.com/documentation/2.5.x/ScalaWS#using-wsclient
• https://www.playframework.com/documentation/2.5.x/ScalaTestingWebServiceClients

有关独立WSClient使用的更详细示例.如果要从早期版本迁移,请参阅https://www.playframework.com/documentation/2.5.x/Migration25#Play-WS-upgrades-to-AsyncHttpClient-2

对于Play 2.4:

不要将原始AsyncHttpClientConfig.Builder用于HTTPS - 它不会使用主机名验证配置安全SSLContext.

您可以使用以下代码创建新的WSClient实例:

import play.api.libs.ws.ning._
import play.api.libs.ws._

val config = new NingAsyncHttpClientConfigBuilder(DefaultWSClientConfig()).build()
val builder = new AsyncHttpClientConfig.Builder(config)
val wsClient:WSClient = new NingWSClient(builder.build())

请注意,这将启动在关闭客户端之前不会关闭的线程:

wsClient.underlying[NingWSClient].close()

如果你不关闭它,你可能会遇到内存泄漏.

Answer 2

Play 2.4使得在独立应用程序中使用WS变得非常容易.

以下要点提供了一个很好的工作示例,以下博客文章提供了一个很好的解释.

以下是重点.

配置build.sbt

libraryDependencies ++= Seq(
  "com.typesafe.play" %% "play-ws" % "2.4.0-M2"
)

初始化WS客户端

val config = new NingAsyncHttpClientConfigBuilder(DefaultWSClientConfig()).build
val builder = new AsyncHttpClientConfig.Builder(config)
val client = new NingWSClient(builder.build)

使用WS

client.url("http://www.example.com").get

发布WS资源

client.close()