Question

我在app/Global.scala看到了这样的代码，这是我的同事写的

import java.lang.reflect.Constructor
import securesocial.core.RuntimeEnvironment
import securesocial.core.providers._
import securesocial.core.providers.utils.Mailer
import services.UserService

import scala.collection.immutable.ListMap

object Global extends play.api.GlobalSettings {

  /**
   * The runtime environment for this app.
   */
  object MyRuntimeEnvironment extends RuntimeEnvironment.Default[User] {
    // override lazy val routes = new CustomRoutesService()
    override lazy val userService: UserService = new UserService()
    lazy val MailTemplates: MailTemplates = new MailTemplates(this)
    override lazy val mailer: Mailer = new Mailer(MailTemplates)
    // override lazy val eventListeners = List(new MyEventListener())
    override lazy val providers = ListMap(
      // oauth 2 client providers
      include(new FacebookProvider(routes, cacheService, oauth2ClientFor(FacebookProvider.Facebook))),
      // username password
      include(new UsernamePasswordProvider(userService, avatarService, passwordHashers))
    )
  }

  /**
   * An implementation that checks if the controller expects a RuntimeEnvironment and
   * passes the instance to it if required.
   *
   * This can be replaced by any DI framework to inject it differently.
   *
   * @param controllerClass
   * @tparam A
   * @return
   */
  override def getControllerInstance[A](controllerClass: Class[A]): A = {
    val instance = controllerClass.getConstructors.find { c =>
      val params = c.getParameterTypes
      params.length == 1 && params(0) == classOf[RuntimeEnvironment[User]]
    }.map {
      _.asInstanceOf[Constructor[A]].newInstance(MyRuntimeEnvironment)
    }
    instance.getOrElse(super.getControllerInstance(controllerClass))
  }
}

有人认为在playframework中将服务设置为全局值是否合适？

Answer 1

服务通常是作为无国籍单身人士实施的，所以我会说它没问题。你的问题与一般依赖注入原则有关，而不是与Play相关。

Answer 2

是。在没有使用依赖注入框架的情况下，这是一种标准的依赖注入模式。它允许您请求类似于Spring请求范围的范围变量。

您的实现看起来像是基于正在运行的SecureSocial示例实现。看到 https://github.com/jaliss/securesocial/blob/master/samples/scala/demo/app/Global.scala

在play框架中设置这样的GLOBAL变量是一个好习惯吗？

2 个答案: