Google Guice binding using Annotation and Key class

Question

Lets say we have A.java interface implemented by AImpl.java and B.java implemented by Bimpl.java

Above classes are binded in two modules as below

Module1 {
    bind(A.class).to(AImpl.class);
    bind(B.class).to(BImpl.class);
}

Module2 {
    Key<A> aKey = Key.get(A.class, AnAnnot.class);
    bind(aKey).to(AImpl.class);
    Key<B> bKey = Key.get(B.class, AnAnnot.class);
    bind(bKey).to(BImpl.class);
}


Class AImpl implements A {
}

Class BImpl implements B {

@Inject
BImpl(A aImpl) {
 //??
}
}

BImpl refers to A

For BImpl binded using Annotation, I want corresponding aImpl, binded using Annotation but here I'm getting aImpl which is not binded using Annotation

Please suggest

Answer 1

I'm able to achieve using below pattern. May be there is a more easier way. Happy to know more

A.java

public interface A {
    String aMethod();
}

AImpl.java

public class AImpl implements A {

    private String moduleName;

    public AImpl(String moduleName) {
        this.moduleName = moduleName;
    }

    @Override
    public String aMethod() {
        return moduleName;
    }
}

B.java

public interface B {
    String bMethod();
}

Bimpl.java

public class BImpl implements B {
    private final A a;

    BImpl(A a) {
        this.a = a;
    }

    @Override
    public String bMethod() {
        return a.aMethod();
    }
}

AnAnnot.java

@Target(PARAMETER)
@Retention(RUNTIME)
@BindingAnnotation
public @interface AnAnnot {
}

BProvider.java

public class BProvider  implements Provider<B> {
    private final A a;

    @Inject
    BProvider(A a) {
        this.a = a;
    }

    @Override
    public B get() {
        return new BImpl(a);
    }
}

BHavingAnnotatedA.java

public class BHavingAnnotatedA implements Provider<B> {
    private final A a;

    @Inject
    BHavingAnnotatedA(@AnAnnot A a) {
        this.a = a;
    }

    @Override
    public B get() {
        return new BImpl(a);
    }
}

ABModule1.java

public class ABModule1 extends AbstractModule {

    @Override
    protected void configure() {
        bind(A.class).to(AImpl.class);
        bind(B.class).toProvider(BProvider.class);
    }
}

ABModule2.java

public class ABModule2 extends AbstractModule {

    @Override
    protected void configure() {
        Key<A> aKey = Key.get(A.class, AnAnnot.class);
        bind(aKey).to(AImpl.class);
        Key<B> bKey = Key.get(B.class, AnAnnot.class);
        bind(bKey).toProvider(BHavingAnnotatedA.class);
    }
}