Scala - 当依赖类也使用相同的泛型类型时,使用guice注入泛型类型

Question

我想使用Guice为Generic类型注入依赖.在scala中查找以下示例来复制问题.

ProductModel.scala

trait BaseProduct  

case class Product() extends BaseProduct 

CartService.scala

class CartService[A <: BaseProduct] @Inject()(productService : ProductService[A]) {
 def getCartItems = productService.getProduct
}

ProductService.scala

class ProductService[A]{
 def getProduct = println("ProductService")
}

Main.scala

object Main extends App {

  val injector = Guice.createInjector(new ShoppingModule)
  val cartService = injector.getInstance(classOf[CartService[Product]])
  cartService.getCartItems
}

class ShoppingModule extends AbstractModule with ScalaModule {
  override def configure(): Unit = {
    bind[BaseProduct].to(scalaguice.typeLiteral[Product])
  }
}

运行此Main.scala应用程序时出现以下错误.

service.ProductService<A> cannot be used as a key; It is not fully specified.

我尝试使用codingwell库进行绑定.但它无法识别ProductService Type.

Answer 1

当你在那个时候建立cartService的情况下使用typeLiteral创建实例像

val cartService = injector.getInstance(Key.get(scalaguice.typeLiteral[CartService[Product]])

如果您创建上面的实例,则无需创建模块.使用默认模块创建注入器(如果在应用程序级别的默认Module.scala中有任何其他绑定,则非常有用)

val appBuilder = new GuiceApplicationBuilder()
val injector = Guice.createInjector(appBuilder.applicationModule())

如果你没有任何模块,你可以跳过传递模块作为参数并创建注入器而不传递任何模块

val injector = Guice.createInjector()