Scala/SBT：“对象不是包的成员”，但对象位于外部库中

Question

在Scala2.13.4/SBT1.2.8项目中，类MyService.scala具有以下导入：

import play.api.libs.concurrent.AkkaGuiceSupport

我认为包含该类的库是由sbt作为我在build.sbt中作为libraryDependencies添加的一个库的依赖项添加的。

但是，当我编译该项目时，我得到：

$ sbt -java-home /usr/lib/jvm/java-8 -jvm-debug 9999 run
...
[info] Compiling 31 Scala sources and 1 Java source to /home/me/projects/my_project/target/scala-2.13/classes ...
[error] /home/me/projects/my_project/app/actors/MyService.scala:8:8: object AkkaGuiceSupport is not a member of package play.api.libs.concurrent
[error] import play.api.libs.concurrent.AkkaGuiceSupport
[error]        ^

在IntelliJ中，在项目的外部库中，我可以看到：

​

​

，我在这里错过了什么？

这个编译错误的原因是什么？

........................................................

更新：

build.sbt

name := "CH07"

version := "1.0"

lazy val `ch07` = (project in file(".")).enablePlugins(PlayScala)

scalaVersion := "2.13.4"

resolvers += "Spy Repository" at "http://files.couchbase.com/maven2"

libraryDependencies ++= Seq(
  jdbc,
  cacheApi,
  ws,
  "com.github.mumoshu" %% "play2-memcached-play28" % "0.11.0",
  "org.hsqldb" % "hsqldb" % "2.5.0",
  "org.jooq" % "jooq" % "3.14.4",
  "org.jooq" % "jooq-codegen-maven" % "3.14.4",
  "org.jooq" % "jooq-meta" % "3.14.4",
  "joda-time" % "joda-time" % "2.7",
  "com.ning" % "async-http-client" % "1.9.29",
  "com.github.scullxbones" %% "akka-persistence-mongo-common" % "3.0.5",
  "com.typesafe.akka" %% "akka-persistence" % "2.6.10",
  "com.typesafe.akka" %% "akka-persistence-query" % "2.6.10",
  "com.typesafe.akka" %% "akka-persistence-typed" % "2.6.10"
)

routesGenerator := InjectedRoutesGenerator

project/plugins.sbt

addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.8.7")

project/build.properties

sbt.version=1.3.10

Answer 1

首先，您可以看到它，因为它是play框架的一部分。您可以在PlayImport中看到更多您没有导入的包，但它们是因为播放而出现的。例如，如果从jdbc中删除libraryDependencies，您可能会看到更多这样的错误(只是使用不同的包名，并且只在实际使用的情况下)。请注意，您将能够在IntelliJ树中找到缺少的类，而编译器不会。

在您的示例中，缺少的导入是guice。AkkaGuiceSupport是guice的一部分。尝试将其添加到库依赖项中：

libraryDependencies ++= Seq(
  guice, // This is the missing part
  jdbc,
  cacheApi,
  ws,
  "com.github.mumoshu" %% "play2-memcached-play28" % "0.11.0",
  "org.hsqldb" % "hsqldb" % "2.5.0",
  "org.jooq" % "jooq" % "3.14.4",
  "org.jooq" % "jooq-codegen-maven" % "3.14.4",
  "org.jooq" % "jooq-meta" % "3.14.4",
  "joda-time" % "joda-time" % "2.7",
  "com.ning" % "async-http-client" % "1.9.29",
  "com.github.scullxbones" %% "akka-persistence-mongo-common" % "3.0.5",
  "com.typesafe.akka" %% "akka-persistence" % "2.6.10",
  "com.typesafe.akka" %% "akka-persistence-query" % "2.6.10",
  "com.typesafe.akka" %% "akka-persistence-typed" % "2.6.10"
)