将@Provides方法绑定为渴望的单例 [英] Binding @Provides method as eager singleton

问题描述

我想使用用@Provides注释的方法将其绑定为一个渴望的单例.我发现了错误216 ，这表明这不是不可能，但没有明确提及@Provides注释.

I want to make a binding using a method annotated with @Provides into an eager singleton. I've found bug 216, which suggests this isn't possible, but doesn't mention the @Provides annotation explicitly.

我目前有一个类，它本身就是一个单例，它会及时请求eager个单例，但这不是一个很好的解决方案.

I currently have a class that requests the eager singletons in time by itself being a singleton, but it's not a very nice solution.

public class LogicModule extends AbstractModule {
    @Override public void configure() {
        bind(SomeDep.class);
        bind(MyWorkaround.class).asEagerSingleton();
    }

    // cannot add eager requirement here
    @Provides @Singleton Logic createLogic(SomeDep dep) {
        return LogicCreator.create(dep);
    }

    private static class MyWorkaround {
        @Inject Logic logic;
    }
}

我可以在注释附近更改一些使变通方法类过时的东西吗?

Can I change something near the comment that would make the workaround class obsolete?

推荐答案

为什么不使用

bind(Logic.class).toInstance(LogicCreator.create(dep)); 
//ohh we missing dep

那我们就可以做到

class LogicProvider implements Provider<Logic> {

    private final SomeDep dep;

    @Inject
    public LogicProvider(SomeDep dep) {
      this.dep = dep;
    }

    @Override
    public Logic get() {
      return LogicCreator.create(dep);
    }

}

然后

bind(Logic.class).toProvider(LogicProvider.class).asEagerSingleton();

您甚至可以将SomeDep dep作为Provider<SomeDep>传递给您的提供者，然后在LogicCreator.create()中调用providerDep.get()，这会更可靠.

You can even pass SomeDep dep to your provider as Provider<SomeDep> and then call providerDep.get() in LogicCreator.create() that would be a bit more robust.

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