Guice辅助注入多个接口实现

Question

public static PrivateModule getAFactoryModule(final String factoryBindingKey,final Class<? extends A> targetClassToCreate) {
    return new PrivateModule() {

        @Override
        public void configure() {
            install(new FactoryModuleBuilder().implement(
                    A.class, targetClassToCreate).build(
                    AFactory.class));

            bind(AFactory.class).annotatedWith(Names.named(factoryBindingKey)).to(
                    Key.get(AFactory.class));
            expose(Key.get(AFactory.class, Names.named(factoryBindingKey)));
        }
    };
}

install(getAFactoryModule("B", B.class));
install(getAFactoryModule("C", C.class));
install(getAFactoryModule("D", D.class));

com.guice.test.B has @AssistedInject constructors but none of them match the parameters in method com.guice.test.AFactory.createD(). Unable to create assisted inject

com.guice.test.C has @AssistedInject constructors but none of them match the parameters in method com.guice.test.AFactory.createD(). Unable to create assisted inject

com.guice.test.D has @AssistedInject constructors but none of them match the parameters in method com.guice.test.AFactory.create(). Unable to create assisted inject

看来Guice正在尝试使用不同于预期的创建方法。你知道怎么解决这个问题吗？如有任何指示，将不胜感激！

谢谢！

Answer 1

这听起来像是您在做一些不安全的事情--让您的一些工厂方法未解析--而Guice也很困惑。基本上，FactoryModuleBuilder正在生成以下代码：

@Named("B") public class GeneratedBClass implements AFactory {
  A create(int b, int c) { return new B(...); }
  A create(int d) { /* no implementation! */ }
}
@Named("C") public class GeneratedBClass implements AFactory {
  A create(int b, int c) { return new C(...); }
  A create(int d) { /* no implementation! */ }
}
@Named("D") public class GeneratedBClass implements AFactory {
  A create(int b, int c) { /* no implementation! */ }
  A create(int d) { return new D(...); }
}

这三个缺失的实现是Guice抱怨的原因：Guice找不到一个好的实现，并且你想要把它们连线起来。但是，除了Guice之外，您还设计了一个非常危险的API：根据您的配置，您的方法中的一个可以工作，而另一个不能工作--这比DI的设计更危险。

我要么将您的配置切换为仅切换“B”和“C”，并让这两个选项都显示一个“D”：

public interface AFactory {
  @Named("BorC") A create(int B, int C);
  @Named("D") A create(int D);
}

install(new FactoryModuleBuilder()
    .implement(A.class, Names.named("BorC"), targetClassToCreate)
    .implement(D.class, Names.named("D"), D.class)
    .build(AFactory.class));

public interface DFactory {
  D create(int D);
}

// If DFactory creates an A, you need implement(). Otherwise, this works.
install(new FactoryModuleBuilder().build(DFactory.class));