Java:JSR330

JSR330定义了Java依赖注入的标准。主要提供了一系列的定义(javax.inject.*):

  • Provider<T> Provides instances of T.
  • Inject Identifies injectable constructors, methods, and fields.
  • Named String-based qualifier.
  • Qualifier Identifies qualifier annotations.
  • Scope Identifies scope annotations.
  • Singleton Identifies a type that the injector only instantiates once.

@Inject

see this post

public interface Payment {
    void pay(BigDecimal amount);
}

public class CashPaymentImpl implements Payment {

    private static final Logger LOGGER = Logger.getLogger(CashPaymentImpl.class.toString());

    @Override
    public void pay(BigDecimal amount) {
        LOGGER.log(Level.INFO, "payed {0} cash", amount.toString());
    }
}

@Inject private Payment payment;

@Named

@Named("cash")
public class CashPaymentImpl implements Payment {

    private static final Logger LOGGER = Logger.getLogger(CashPaymentImpl.class.toString());

    @Override
    public void pay(BigDecimal amount) {
        LOGGER.log(Level.INFO, "payed {0} cash", amount.toString());
    }
}
@Named("visa")
public class VisaPaymentImpl implements Payment {

    private static final Logger LOGGER = Logger.getLogger(VisaPaymentImpl.class.toString());

    @Override
    public void pay(BigDecimal amount) {
        LOGGER.log(Level.INFO, "payed {0} with visa", amount.toString());
    }
}
@Inject private @Named("visa") Payment payment;

@Singleton

@Qualifier

@java.lang.annotation.Documented
@java.lang.annotation.Retention(RetentionPolicy.RUNTIME)
@javax.inject.Qualifier

public @interface CashPayment {}
@java.lang.annotation.Documented
@java.lang.annotation.Retention(RetentionPolicy.RUNTIME)
@javax.inject.Qualifier
public @interface VisaPayment {}

@CashPayment
public class CashPaymentImpl implements Payment {
...
}
@VisaPayment
public class VisaPaymentImpl implements Payment {
...
}

@Inject private @VisaPayment Payment payment;

@Scope

Provider<T>