Hi,
You don't need an implementation of Payment Factory by yourself, just
define the factory interface and method, Guice will do the injection.
something like this :
public interface IPayment {
void pay();
}
The implementations of IPayment:
public class CashPayment implements IPayment{
private int cash;
@Inject
public CashPayment(@Assisted int cash) {
this.cash = cash;
}
@Override
public void pay() {
System.out.println("Pay["+cash+"] from Cash");
}
}
another one :
public class CardPayment implements IPayment{
private int cash;
private int card;
@Inject
public CardPayment(@Assisted("cash") int cash, @Assisted("card") int
card) {
this.card = card;
this.cash = cash;
}
@Override
public void pay() {
System.out.println("Pay["+cash+"] from Card["+card+"]");
}
}
Then define your factory:
public interface PaymentFactory {
@Named("cash") IPayment getCashPayment(int cash);
/*
* The types of the factory method's parameters must be distinct.
* To use multiple parameters of the same type, use a named
@Assisted annotation to disambiguate the parameters.
* The names must be applied to the factory method's parameters
*/
@Named("card") IPayment getCardPayment(@Assisted("cash") int cash,
@Assisted("card") int card);
}
your config module :
public class PaymentModule extends AbstractModule {
@Override
protected void configure() {
install(new FactoryModuleBuilder()
.implement(IPayment.class, Names.named(
"cash"),CashPayment.class)
.implement(IPayment.class, Names.named(
"card"),CardPayment.class)
.build(PaymentFactory.class));
}
}
Let's take a test :
public class RealPayment {
public static void main(String[] args) {
Injector injector = Guice.createInjector(new PaymentModule
());
PaymentFactory factory = injector.getInstance(PaymentFactory
.class);
factory.getCashPayment(10).pay();
factory.getCardPayment(10, 123456789).pay();
}
}
For more usage of factory injection , please refer to :
http://google.github.io/guice/api-docs/latest/javadoc/index.html
https://github.com/google/guice/wiki/AssistedInject
在 2014年8月10日星期日UTC+8上午6时29分50秒，rails写道：
>
> Lets say I have a service called Guice service and here is its constructor
>
> public GuiceService(IPayment payment) {
> this.payment = payment;}
>
> And my code used to create it using an Enum
>
> IPayment payment = new PaymentFactory.create(PaymentType.Cash);NaiveService
> naiveService = new NaiveService(payment);
>
> And I had to have a factory implementation somewhere. Something like this
>
> public IPayment create(PaymentType paymentType) {
> IPayment cardPayment = null;
> switch (paymentType) {
> case Cash:
> cardPayment = new CashPayment(100);
> break;
> case Card:
> cardPayment = new CardPayment(10, 100);
> break;
> }
> return cardPayment;
>
> Now I want to use Guice and I guess I want to use FactoryModuleBuilder.
>
> 1.
>
> What is the way to do it if I have more that one implentation of
> IPayment.
> (e.g. CardPayment, CashPayment)
> This works for one
>
> install(new FactoryModuleBuilder()
> .implement(IPayment.class, CashPayment.class)
> .build(IPaymentFactory.class));
>
> 2. How do I implement the constructor ?
> will it still get IPayment? or will it get the factoryImpl created by
> Guice?
>
> Thanks
>
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