asEagerSingleton 与工厂

Question

我是 Guice 的新手，但我有一个我认为通常会这样创建的单例：

@Provides
@Singleton
private SomeClass getSomeClass()
{
    return someClassFactory(configuration);
}

但是，我希望它被热切地初始化。当我删除 @Singleton 注释并尝试 bind(SomeClass.class).asEagerSingleton() 我得到错误：

 1) No implementation for SomeClass was bound.
 2) A binding to SomeClass was already configured

如何提供使用参数或工厂构造的 Eagerly 初始化单例？

Answer 1

@Provides 注释是为 SomeClass 配置绑定的单独方法；它与 bind(SomeClass.class).asEagerSingleton() 绑定冲突。

要修复它，您需要编写一个显式提供程序 class 并使用 toProvider:

绑定它

class MyModule extends AbstractModule {

  private static class MyProvider implements Provider<SomeClass> {
    private final OtherStuff otherStuff;

    @Inject
    MyProvider(OtherStuff otherStuff) {
      // Inject constructor params if your @Provides method took arguments
      this.otherStuff = otherStuff;
    }

    public SomeClass get() {
      return new SomeClass(otherStuff);
    }
  }

  protected void configure() {
    bind(SomeClass.class).toProvider(MyProvider.class).asEagerSingleton();
  }
}

asEagerSingleton 与工厂

asEagerSingleton with factory

java

guice