I got the bindings wrong, correcting that. Also illustrating how the
superclass of Providers gets common dependencies.
public class MyModule extends AbstractModule {
@Override
protected void configure() {
bind(ExecutorService.class)
.annotatedWith(Names.named("single"))
.toProvider(SingleProvider.class);
bind(ExecutorService.class)
.annotatedWith(Names.named("pool"))
.toProvider(PoolProvider.class);
}
}
class SomeDependency {}
class AnotherDependency {}
class CommonDependency1 {}
class CommonDependency2 {}
class CommonDependency3 {}
abstract class GenericExecutorProvider implements Provider<ExecutorService>
{
@Inject
GenericExecutorProvider(final CommonDependency1 d1,
final CommonDependency2 d2,
final CommonDependency3 d3) {}
public abstract ExecutorService get();
}
class SingleProvider extends GenericExecutorProvider {
@Inject
SingleProvider(final SomeDependency d,
final CommonDependency1 d1,
final CommonDependency2 d2,
final CommonDependency3 d3) {
super(d1,d2,d3);
}
public ExecutorService get() {
// construct and return an ExecutorService
// based on SomeDependency
return null;
}
}
class PoolProvider extends GenericExecutorProvider {
@Inject
PoolProvider(final AnotherDependency d,
final CommonDependency1 d1,
final CommonDependency2 d2,
final CommonDependency3 d3) {
super(d1,d2,d3);
}
public ExecutorService get() {
// construct and return an ExecutorService
// based on AnotherDependency
return null;
}
}
On Wed, Mar 9, 2011 at 10:18 AM, Russ Milliken <[email protected]>wrote:
> I would do the "class" solution in a more OO way (eliminate the "switch"):
>
> public class MyModule extends AbstractModule {
>
> @Override
> protected void configure() {
> bind(GenericExecutorProvider.class)
> .annotatedWith(Names.named("single"))
> .to(SingleProvider.class);
>
> bind(GenericExecutorProvider.class)
> .annotatedWith(Names.named("pool"))
> .to(PoolProvider.class);
> }
> }
>
> abstract class GenericExecutorProvider implements Provider<ExecutorService>
> {
> public abstract ExecutorService get();
> }
>
> class SingleProvider extends GenericExecutorProvider {
>
> @Inject
> SingleProvider(final SomeDependency d) { }
>
> public ExecutorService get() {
> // construct and return an ExecutorService
> // based on SomeDependency
> return null;
> }
> }
>
> class PoolProvider extends GenericExecutorProvider {
>
> @Inject
> PoolProvider(final AnotherDependency d) { }
>
> public ExecutorService get() {
> // construct and return an ExecutorService
> // based on AnotherDependency
> return null;
> }
> }
>
>
> 2011/3/9 Sam Berlin <[email protected]>
>
> You can have one provider for both bindings, but the provider can't
>> disambiguate based on what it's providing (that is, there's know of knowing
>> the thing it's providing for).
>>
>> You could do this with less code with @Provides methods (or also simulate
>> it if you're stuck with classes). For example:
>>
>> @Provides @Named("single") ExecutorService provideSingle(AnotherDependency
>> ad) {
>> return makeExecutor(ad, Type.SINGLE);
>> }
>>
>> @Provides @Named("pool") ExecutorService providePool(AnotherDependency
>> ad) {
>> return makeExecutor(ad, Type.POOL);
>> }
>>
>> private ExecutorService makeExecutor(AnotherDependency ad, Type type) {
>> ... }
>>
>> --- or, using classes ---
>>
>> class SingleProvider extends GenericExecutorProvider {
>> SingleProvider() { super(Type.SINGLE); }
>> }
>>
>> class PoolProvider extends GenericExecutorProvider {
>> PoolProvider() { super(Type.POOL); }
>> }
>>
>> class GenericExecutorProvider implmenets Provider<ExecutorService> {
>> final Type type;
>> GenericExecutorProvider(Type type) { this.type = type; }
>>
>> @Inject injectDependency(AnotherDependency ad) { .... }
>>
>> ExecutorService get() {
>> switch(type) { ... }
>> }
>> }
>>
>>
>> sam
>>
>> 2011/3/9 Bahri Gençsoy <[email protected]>
>>
>>
>>> Hi, I am trying to achieve some binding with Guice 2.0. I did search the
>>> mailing list but couldn't find a similar problem/solution.
>>>
>>> I am trying to bind different implementations of same interface. I want
>>> to discriminate them against their annotations.
>>>
>>> These are my classes to be injected dependencies to, I do not want to
>>> change them a lot:
>>>
>>> class SingleRunner {
>>> @Inject
>>> public void setExecutor(@Named("single") ExecutorService executor) {
>>> // ...
>>> }
>>> }
>>>
>>> class PoolRunner {
>>> @Inject
>>> public void setExecutor(@Named("pool") ExecutorService executor) {
>>> // ...
>>> }
>>> }
>>>
>>> This is the traditional approach to bind providers for these classes;
>>> creating to provider classes and bind them:
>>>
>>> class SingleProvider implements Provider<ExecutorService> {
>>> @Inject
>>> private SomeOtherDependency other;
>>>
>>> public ExecutorService get() {
>>> return singleExecutorService;
>>> }
>>>
>>> }
>>>
>>> class PoolProvider implements Provider<ExecutorService> {
>>> @Inject
>>> private SomeOtherDependency other;
>>>
>>> public ExecutorService get() {
>>> return poolExecutorService;
>>> }
>>>
>>> }
>>>
>>> class MyModule extends AbstractModule {
>>> @Override
>>> protected void configure() {
>>>
>>> bind(ExecutorService.class).annotatedWith(Names.named("pool")).toProvider(PoolProvider.class);
>>>
>>> bind(ExecutorService.class).annotatedWith(Names.named("single")).toProvider(SingleProvider.class);
>>> }
>>> }
>>>
>>> But I am not comfortable with creating two provider classes. I want one
>>> provider class to provide all instances, ie something like that:
>>>
>>> class AllExecutorProvider {
>>> @Inject
>>> public void setSomeOtherDependency(SomeOtherdependency dep) {
>>> // ...
>>> }
>>>
>>> public ExecutorService getExecutor(String name) {
>>> if (name.equals("pool")) {
>>> return poolExecutor;
>>> } else if (name.equals("single")) {
>>> return singleExecutor;
>>> } else {
>>> return null;
>>> }
>>> }
>>> }
>>>
>>>
>>> Thanks in advance
>>>
>>>
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>>
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>
>
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