java - 如何编写通用的 Guice 绑定(bind)函数？

Question

如何在下面的 Guice 绑定(bind)代码中抽象选项类型，用通用参数替换 Option ?

ArrayList<Class<? extends Option>> options = 
 new ArrayList<Class<? extends Option>>();
bindMultibinder(annotation, options);

public Key<Set<Option>> bindMultibinder(
 Named annotation, ArrayList<Class<? extends Option>> contents) {
   Multibinder<Option> options = 
    Multibinder.newSetBinder(binder(), Option.class, annotation);
   for (Class<? extends Option> option : contents) {
      options.addBinding().to(option);
   }
   final Key<Set<Option>> multibinderKey = 
    Key.get(new TypeLiteral<Set<Option>>(){}, annotation);
   return multibinderKey;
}

Answer 1

感谢 Stuart McCulloch在 Google 网上论坛上回答:

^ the new TypeLiteral<...>(){} anonymous class trick only works when the type parameter is known at compile time.

If you need to build generic types at runtime you can use the com.google.inject.util.Types utility class, for example:

final Key<Set<T>> multibinderKey =
    Key.get( Types.setOf( superClass ), annotation );

为了使其正确构建，我对其进行了如下修改:

final Key<?> multibinderKey = Key.get(Types.setOf( superClass ), annotation);

所以完整的通用方法是:

public <T> Key<?> bindMultibinder(
 Named annotation, Class<T> superClass, ArrayList<Class<? extends T>> contents) {
   Multibinder<T> options = 
    Multibinder.newSetBinder(binder(), superClass, annotation);
   for (Class<? extends T> t : contents) {
      options.addBinding().to(t);
   }
   final Key<?> multibinderKey = Key.get(Types.setOf( superClass ), annotation);
   return multibinderKey;
}