Scala播放-ProvisionException:找不到合适的构造函数

我到处都找了，但答案没有帮助。以下是stacktrace：

! @7832lo6ll - Internal server error, for (GET) [/] ->

play.api.UnexpectedException: Unexpected exception[ProvisionException: Unable to provision, see the following errors:

1) Could not find a suitable constructor in controllers.FileCtrl. Classes must have either one (and only one) constructor annotated with @Inject or a zero-argument constructor that is not private.
  at controllers.FileCtrl.class(FileCtrl.scala:34)
  while locating controllers.FileCtrl
    for parameter 11 at router.Routes.<init>(Routes.scala:155)
  while locating router.Routes
  while locating play.api.inject.RoutesProvider
  while locating play.api.routing.Router

1 error]
        at play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1$$anonfun$apply$1$$anonfun$1.apply(DevServerStart.scala:165) ~[play-server_2.11-2.4.11.jar:2.4.11]
        at play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1$$anonfun$apply$1$$anonfun$1.apply(DevServerStart.scala:121) ~[play-server_2.11-2.4.11.jar:2.4.11]
        at scala.Option.map(Option.scala:146) ~[scala-library-2.11.8.jar:na]
        at play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1$$anonfun$apply$1.apply(DevServerStart.scala:121) ~[play-server_2.11-2.4.11.jar:2.4.11]
        at play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1$$anonfun$apply$1.apply(DevServerStart.scala:119) ~[play-server_2.11-2.4.11.jar:2.4.11]
        at scala.util.Success.flatMap(Try.scala:231) ~[scala-library-2.11.8.jar:na]
        at play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1.apply(DevServerStart.scala:119) ~[play-server_2.11-2.4.11.jar:2.4.11]
        at play.core.server.DevServerStart$$anonfun$mainDev$1$$anon$1$$anonfun$get$1.apply(DevServerStart.scala:111) ~[play-server_2.11-2.4.11.jar:2.4.11]
        at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24) ~[scala-library-2.11.8.jar:na]
        at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24) ~[scala-library-2.11.8.jar:na]
Caused by: com.google.inject.ProvisionException: Unable to provision, see the following errors:

1) Could not find a suitable constructor in controllers.FileCtrl. Classes must have either one (and only one) constructor annotated with @Inject or a zero-argument constructor that is not private.
  at controllers.FileCtrl.class(FileCtrl.scala:34)
  while locating controllers.FileCtrl
    for parameter 11 at router.Routes.<init>(Routes.scala:155)
  while locating router.Routes
  while locating play.api.inject.RoutesProvider
  while locating play.api.routing.Router

1 error
        at com.google.inject.internal.InjectorImpl$2.get(InjectorImpl.java:1025) ~[guice-4.0.jar:na]
        at com.google.inject.internal.InjectorImpl.getInstance(InjectorImpl.java:1051) ~[guice-4.0.jar:na]
        at play.api.inject.guice.GuiceInjector.instanceOf(GuiceInjectorBuilder.scala:321) ~[play_2.11-2.4.11.jar:2.4.11]
        at play.api.inject.guice.GuiceInjector.instanceOf(GuiceInjectorBuilder.scala:316) ~[play_2.11-2.4.11.jar:2.4.11]
        at play.api.Application$class.routes(Application.scala:112) ~[play_2.11-2.4.11.jar:2.4.11]
        at play.api.DefaultApplication.routes(Application.scala:241) ~[play_2.11-2.4.11.jar:2.4.11]
        at play.api.Play$$anonfun$start$1.apply$mcV$sp(Play.scala:90) ~[play_2.11-2.4.11.jar:2.4.11]
        at play.api.Play$$anonfun$start$1.apply(Play.scala:87) ~[play_2.11-2.4.11.jar:2.4.11]
        at play.api.Play$$anonfun$start$1.apply(Play.scala:87) ~[play_2.11-2.4.11.jar:2.4.11]
        at play.utils.Threads$.withContextClassLoader(Threads.scala:21) ~[play_2.11-2.4.11.jar:2.4.11]

所以实际上有一个@Inject

播放版本为2.4，Scala版本为2.11.6

---

最让我困惑的是stacktrace没有提到任何进一步的问题，例如，没有提到注入类，这可能是这里的问题。

只是为了测试，也许您可以尝试messagesApi的普通构造函数参数，而不是curried版本？所以不是

(val messagesApi: MessagesApi) 

只是

---

您是否尝试隐式传递messagesApi？

(val messagesApi: MessagesApi) 

([other constructor params ...], val messagesApi: MessagesApi)