依赖注入到Play Framework 2.5模块 [英] Dependency Injection to Play Framework 2.5 modules

问题描述

我有一个带有以下签名的模块类:

I have a module class with the following signature:

class SilhouetteModule extends AbstractModule with ScalaModule {

我想注入配置:

class SilhouetteModule @Inject() (configuration: Configuration) extends AbstractModule with ScalaModule {

但是它失败，并出现以下错误.

But it fails with the following error.

No valid constructors
Module [modules.SilhouetteModule] cannot be instantiated.

Play文档提到

在大多数情况下，如果在创建组件时需要访问配置"，则应将配置"对象注入组件本身或...

In most cases, if you need to access Configuration when you create a component, you should inject the Configuration object into the component itself or...

，但我不知道如何成功完成.所以问题是，如何在Play 2.5中将依赖项注入模块类中?

, but I can't figure out how to do it successfully. So the question is, how do I inject a dependency into a module class in Play 2.5?

推荐答案

有两种解决方案可以解决您的问题.

There are two solutions to solve your problem.

第一个(以及更简单的一个):不要扩展 com.google.inject.AbstractModule .而是使用 play.api.inject.Module .扩展将强制您覆盖 def绑定(环境:环境，配置:配置):Seq [Binding [_]] .在该方法中，您可以进行所有绑定，然后将配置作为方法参数插入.

First one (and the more straight forward one): Do not extend the com.google.inject.AbstractModule. Instead use the play.api.inject.Module. Extending that forces you to override def bindings(environment: Environment, configuration: Configuration): Seq[Binding[_]]. Within that method you could do all your bindings and you get the configuration inserted as a method-parameter.

第二个(以及更灵活的一个):根据要注入的组件的需求，可以为要绑定的组件定义提供程序.在该提供程序中，您可以注入所需的任何内容.例如

Second one (and the more flexible one): Depending on your needs of the components you want to inject, you could define a provider for the component you want to bind. In that provider you could inject whatever you want. E.g.

import com.google.inject.Provider

class MyComponentProvider @Inject()(configuration:Configuration) extends Provider[MyComponent] {
    override def get(): MyComponent = {
        //do what ever you like to do with the configuration
        // return an instance of MyComponent
    }
}

然后，您可以在模块中绑定组件:

Then you could bind your component within your module:

class SilhouetteModule extends AbstractModule {
    override def configure(): Unit = {
        bind(classOf[MyComponent]).toProvider(classOf[MyComponentProvider])
    }
}

第二个版本的优点是，您可以注入自己喜欢的任何内容.在第一个版本中，您只是"配置.

The advantage of the second version, is that you are able to inject what ever you like. In the first version you get "just" the configuration.

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