On 10 June 2010 21:57, Itay Maman <[email protected]> wrote:
> Hi Guys,
>
> I posted my problem as a SO question:
> http://stackoverflow.com/questions/3014140.
> If someone has a solution I'd be grateful if he could post it (either
> here or at SO)
>
answered over at SO, copied here...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Here's one solution based on your original code - there are three changes:
1. Move the bindings for A, C, and D into a separate sub-module
2. Mark A as a singleton in the sub-module
3. Use a @Provides method in the main-module to provide instances of
BImpl with
a new child injector for each request - this is where the sub-module
comes in
This works because the singleton binding for A is now limited to each child
injector.
[ Note: you could always cache the sub-module instance in a field of the
main-module if you don't want to keep creating it for each request of B ]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
import java.util.*;
import com.google.inject.*;
public class Main {
public static class Super {
private static Map<Class<?>,Integer> map = new
HashMap<Class<?>,Integer>();
private Integer value;
public Super(Object... args) {
value = map.get(getClass());
value = value == null ? 0 : ++value;
map.put(getClass(), value);
if(args.length > 0)
System.out.println("Created " + this + " with " +
Arrays.toString(args));
}
@Override
public final String toString() {
return "" + getClass().getSimpleName().charAt(0) + value;
}
}
public interface A { }
public static class AImpl extends Super implements A { }
public interface B { }
public static class BImpl extends Super implements B {
@Inject public BImpl(C c, D d) { super(c,d); }
}
public interface C { }
public static class CImpl extends Super implements C {
@Inject public CImpl(A a) { super(a); }
}
public interface D { }
public static class DImpl extends Super implements D {
@Inject public DImpl(A a) { super(a); }
}
public static class MyModule extends AbstractModule {
@Override
protected void configure() {}
// >>>>>>>>
@Provides
B builder( Injector injector ) {
return injector.createChildInjector( new SubModule()
).getInstance( BImpl.class );
}
// <<<<<<<<
}
// >>>>>>>>
public static class SubModule extends AbstractModule {
@Override
protected void configure() {
bind(A.class).to(AImpl.class).in( Scopes.SINGLETON );
bind(C.class).to(CImpl.class);
bind(D.class).to(DImpl.class);
}
}
// <<<<<<<<
public static void main(String[] args) {
Injector inj = Guice.createInjector(new MyModule());
inj.getInstance(B.class);
inj.getInstance(B.class);
}
}
Thanks,
> -Itay
>
> http://twitter.com/pembleton
>
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--
Cheers, Stuart
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