玩框架没有依赖注入？

Question

在不讨论原因的情况下，假设有人想要一个老式的Play Framework web服务，并且不想使用依赖注入，也不想依赖Google的Guice。在玩法2.8.x中还可能吗？

package controllers
import javax.inject._
import play.api.mvc._
class HomeController @Inject() (val controllerComponents: ControllerComponents) extends BaseController {
  def index = Action {
    Ok("It works!")
  }
}

package controllers
import play.api.mvc.{Action, AnyContent, Controller}
object TestController {
  def index:Action[AnyContent] = Action {
    Ok("It used to work.")
  }
}

[info] Compiling 1 Scala source to /Volumes/.../play-scala-seed/target/scala-2.13/classes ...
[error] p.a.h.DefaultHttpErrorHandler - 

! @7ef69nl6l - Internal server error, for (GET) [/test/] ->

play.api.UnexpectedException: Unexpected exception[CreationException: Unable to create injector, see the following errors:

1) Could not find a suitable constructor in controllers.TestController. Classes must have either one (and only one) constructor annotated with @Inject or a zero-argument constructor that is not private.
  at controllers.TestController.class(TestController.scala:3)
  while locating controllers.TestController
    for the 4th parameter of router.Routes.<init>(Routes.scala:33)
  at play.api.inject.RoutesProvider$.bindingsFromConfiguration(BuiltinModule.scala:137):
Binding(class router.Routes to self) (via modules: com.google.inject.util.Modules$OverrideModule -> play.api.inject.guice.GuiceableModuleConversions$$anon$4)

1 error]
    at play.core.server.DevServerStart$$anon$1.reload(DevServerStart.scala:210)
    at play.core.server.DevServerStart$$anon$1.get(DevServerStart.scala:141)
    at play.core.server.AkkaHttpServer.handleRequest(AkkaHttpServer.scala:296)
    at play.core.server.AkkaHttpServer.$anonfun$createServerBinding$1(AkkaHttpServer.scala:186)
    at akka.stream.impl.fusing.MapAsync$$anon$30.onPush(Ops.scala:1261)
    at akka.stream.impl.fusing.GraphInterpreter.processPush(GraphInterpreter.scala:541)
    at akka.stream.impl.fusing.GraphInterpreter.execute(GraphInterpreter.scala:423)
    at akka.stream.impl.fusing.GraphInterpreterShell.runBatch(ActorGraphInterpreter.scala:624)
    at akka.stream.impl.fusing.GraphInterpreterShell$AsyncInput.execute(ActorGraphInterpreter.scala:501)
    at akka.stream.impl.fusing.GraphInterpreterShell.processEvent(ActorGraphInterpreter.scala:599)
Caused by: com.google.inject.CreationException: Unable to create injector, see the following errors:

1) Could not find a suitable constructor in controllers.TestController. Classes must have either one (and only one) constructor annotated with @Inject or a zero-argument constructor that is not private.
  at controllers.TestController.class(TestController.scala:3)
  while locating controllers.TestController
    for the 4th parameter of router.Routes.<init>(Routes.scala:33)
  at play.api.inject.RoutesProvider$.bindingsFromConfiguration(BuiltinModule.scala:137):
Binding(class router.Routes to self) (via modules: com.google.inject.util.Modules$OverrideModule -> play.api.inject.guice.GuiceableModuleConversions$$anon$4)

1 error
    at com.google.inject.internal.Errors.throwCreationExceptionIfErrorsExist(Errors.java:543)
    at com.google.inject.internal.InternalInjectorCreator.initializeStatically(InternalInjectorCreator.java:159)
    at com.google.inject.internal.InternalInjectorCreator.build(InternalInjectorCreator.java:106)
    at com.google.inject.Guice.createInjector(Guice.java:87)
    at com.google.inject.Guice.createInjector(Guice.java:78)
    at play.api.inject.guice.GuiceBuilder.injector(GuiceInjectorBuilder.scala:200)
    at play.api.inject.guice.GuiceApplicationBuilder.build(GuiceApplicationBuilder.scala:155)
    at play.api.inject.guice.GuiceApplicationLoader.load(GuiceApplicationLoader.scala:21)
    at play.core.server.DevServerStart$$anon$1.$anonfun$reload$3(DevServerStart.scala:189)
    at play.utils.Threads$.withContextClassLoader(Threads.scala:21)

有没有一个简单的方法可以让你不去这里就呆在老学校里？

我承认，但不完全理解https://www.playframework.com/documentation/2.4.x/migration24。我认为我的问题与2.7中删除了静态路由有关。

Answer 1

我的名声不允许我对Mario Galic的答案发表评论，但您可以使用BuiltinComponentsFromContext提供的“正确”（非测试）ControllerComponents来轻松修改他的示例。

整个示例看起来像

class HomeController(override protected val controllerComponents: ControllerComponents)
  extends BaseController {
  def index = Action { Ok("It works!") }
}

class MyApplicationLoader extends ApplicationLoader {
  def load(context: ApplicationLoader.Context): Application = {
    new BuiltInComponentsFromContext(context) {
      lazy val homeController = HomeController(controllerComponents)
      override lazy val router: Router = Routes(httpErrorHandler, homeController)
    }.application
  }
}