Guice SPI：按通配符类型查找绑定

发布于 2024-07-26 06:19:31 字数 1020 浏览 2 评论 0原文

Guice 提供了一种查找给定类型的所有绑定的方法 (Injector#findBindingsByType)，它还提供了 TypeLiteral 类似乎可以从中构造通配符类型。我想做的是找到由通配符类型参数化的某种类型的所有绑定，但我不知道如何做到这一点。看看 guice src 表明我可能会叫错树，但我想我无论如何都会问一下......所以例如给定一个类型

Foo<E extends Bar>
BarImplOne implements Bar
BarImplTwo implements Bar

和一些绑定，

bind(new TypeLiteral<Foo<BarImplOne>>() {}).to(MyFooOne.class);
bind(new TypeLiteral<Foo<BarImplTwo>>() {}).to(MyFooTwo.class);

然后我希望能够发现这两个绑定

Injector.findBindingsByType(TypeLiteral.get(Types.newParameterizedType(Foo.class, Types.subtypeOf(Bar.class))));

有任何想法吗？

干杯马特

原文

Guice provides a means to find all bindings for a given type (Injector#findBindingsByType) and it also provides a TypeLiteral class from which it seems possible to construct a wildcard type. What I would like to do is find all bindings for some type that is parameterised by a wildcard type but I can't figure out how to do it. A look at the guice src suggests I might be barking up the wrong tree but I figured I'd ask around anyway... so for example given a type

Foo<E extends Bar>
BarImplOne implements Bar
BarImplTwo implements Bar

and some bindings like

bind(new TypeLiteral<Foo<BarImplOne>>() {}).to(MyFooOne.class);
bind(new TypeLiteral<Foo<BarImplTwo>>() {}).to(MyFooTwo.class);

then I want to be able to discover both bindings with something like

Injector.findBindingsByType(TypeLiteral.get(Types.newParameterizedType(Foo.class, Types.subtypeOf(Bar.class))));

Any ideas?

Cheers
Matt

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

月亮邮递员 2024-08-02 06:19:32

不幸的是，没有现成的 API 可以告诉您一个 TypeLiteral 是否可以从另一个 TypeLiteral 分配。您需要使用一堆可怕的 instanceof 检查来执行老式循环。像这样的恶心的事情：

for (Map.Entry<Key<?>, Binding<?>> entry 
    : injector.getBindings().entrySet()) {
  Type type = entry.getKey().getTypeLiteral().getType();
  if (!(type instanceof ParameterizedType)) continue;

  ParameterizedType parameterized = (ParameterizedType) type;
  if (parameterizedType.getRawType() != Foo.class) continue;

  Type parameter = .getActualTypeArguments()[0]
  if (!(parameter instanceof Class)) continue;

  Class<?> parameterClass = (Class<?>) parameter;
  if (!Bar.class.isAssignableFrom(parameterClass)) continue;

  results.add(entry);
}

当然，使用现成的 API 来做一些事情会更好。我欢迎对实现和测试 TypeLiteral.isAssignableFrom(TypeLiteral) 的 Guice 做出贡献。联系我们的用户名单来担任志愿者！

Unfortunately, there's no out-of-the-box API that will tell you whether one TypeLiteral is assignable from another. You'll need to do an old-school loop with a bunch of hideous instanceof checks. Something gross like this:

for (Map.Entry<Key<?>, Binding<?>> entry 
    : injector.getBindings().entrySet()) {
  Type type = entry.getKey().getTypeLiteral().getType();
  if (!(type instanceof ParameterizedType)) continue;

  ParameterizedType parameterized = (ParameterizedType) type;
  if (parameterizedType.getRawType() != Foo.class) continue;

  Type parameter = .getActualTypeArguments()[0]
  if (!(parameter instanceof Class)) continue;

  Class<?> parameterClass = (Class<?>) parameter;
  if (!Bar.class.isAssignableFrom(parameterClass)) continue;

  results.add(entry);
}

Of course, it would be much nicer to do something using an off-the-shelf API. I'd welcome an contribution to Guice that implements and tests TypeLiteral.isAssignableFrom(TypeLiteral). Contact our user's list to volunteer!

回复收藏 0 原文

~没有更多了~