Play Framework多项目结构：routes文件编译报错求助

问题场景 #

基于Play框架搭建多项目结构后，执行sbt clean compile时出现Routes解析错误，所有控制器均位于controllers包下，但编译报错提示找不到controllers.app包下的控制器。单项目结构下运行正常。

目录结构 #

conf
 - application.config
 - routes ..................... -> / app.Routes
modules
 - app
    - conf
       - application.conf ..... play.http.router = app.Routes
       - app.routes
    - controllers ............. 基础控制器（属于controllers包）
project
 - build.properties ........... sbt.version=1.7.1
 - plugins.sbt ................ addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.8.16")
build.sbt ..................... 配置见下文

build.sbt配置 #

name := """scala-play-angular-seed"""

version := "1.0-SNAPSHOT"

lazy val root = (project in file(".")).enablePlugins(PlayScala).dependsOn(app).aggregate(app)

lazy val app = (project in file("modules/app")).enablePlugins(PlayScala).settings(
  watchSources ++= (baseDirectory.value / "ui/src" ** "*").get,
  name := "app",
  scalaVersion := "2.13.8",
  libraryDependencies += guice,
  libraryDependencies += "org.scalatestplus.play" %% "scalatestplus-play" % "5.1.0" % Test,
  libraryDependencies += "com.h2database" % "h2" % "2.1.214"
)

resolvers += Resolver.sonatypeRepo("snapshots")
scalaVersion := "2.13.8"

app.routes内容 #

# Routes
# This file defines all application routes (Higher priority routes first)
# ~~~~

# Serve index page from public directory
GET     /                           controllers.FrontendController.index()

# An example route (Prefix all API routes with apiPrefix defined in application.conf)
GET     /api/summary                controllers.HomeController.appSummary

# An example route (Prefix all API routes with apiPrefix defined in application.conf)
GET     /api/segments                controllers.HomeController.getSegments

# Serve static assets under public directory
GET     /*file                      controllers.app.FrontendController.assetOrDefault(file)

# Test post request
POST    /api/postTest               controllers.HomeController.postTest()

编译错误信息 #

[error] /modules/app/conf/app.routes:6:1: type FrontendController is not a member of package controllers.app
[error] GET     /                           controllers.app.FrontendController.index()
[error] /modules/app/conf/app.routes:9:1: type HomeController is not a member of package controllers.app
[error] GET     /api/summary                controllers.app.HomeController.appSummary
[error] /modules/app/conf/app.routes:6:1: type FrontendController is not a member of package controllers.app
[error] GET     /                           controllers.app.FrontendController.index()
[error] /modules/app/conf/app.routes:9:1: type HomeController is not a member of package controllers.app
[error] GET     /api/summary                controllers.app.HomeController.appSummary
[error] four errors found
[error] (app / Compile / compileIncremental) Compilation failed
[error] Total time: 6 s, completed 15 Sep 2022, 11:42:52

解决方法 #

1. 修正Routes中的控制器路径错误 #

查看app.routes中的静态资源路由行，其中多了不必要的.app前缀，控制器实际位于controllers包下，需修改为：

GET     /*file                      controllers.FrontendController.assetOrDefault(file)

2. 禁用Play多项目模块的自动包前缀 #

Play在多项目模块中，默认会将模块名（此处为app）作为前缀添加到控制器引用上，导致解析成controllers.app.XXX。可通过以下两种方式解决：

• 在模块的modules/app/conf/application.conf中添加配置：

  play.routesGenerator = InjectedRoutesGenerator
  play.routesImport += "controllers._"
  

• 或者直接在app.routes文件顶部添加导入语句：

  import controllers._
  

3. 验证项目依赖与路由引用 #

确认根项目的conf/routes中引用模块路由的路径正确（当前配置-> / app.Routes无误），同时确保模块的application.conf中play.http.router = app.Routes配置与routes文件名一致。

内容的提问来源于stack exchange，提问作者David Tomecek