Compose @Autowired with @Qualifier [SPR-14060]

[spring-projects-issues]

Sam Brannen opened SPR-14060 and commented

Overview

Once #18630 is resolved it will be possible to compose @Autowired with @Qualifier.

Consequently, the following common combination of @Autowired and @Qualifier:

@Autowired
@Qualifier("holidayDateService")
private DateService dateService;

... can be replaced with:

@Autowired("holidayDateService")
private DateService dateService;

Although this may not appear immediately beneficial for DI for fields or setter methods, it becomes much more appealing once @Autowired can be applied to parameters (see #18629).

For example, Spring's testing support for JUnit 5 would then be able to support parameter injection succinctly in test methods as follows.

@Test
void businessHolidays(@Autowired("holidayDateService") DateService dateService) {
}

Proposal

Implement @Autowired as follows.

@Target({ElementType.CONSTRUCTOR, ElementType.FIELD, ElementType.METHOD, ElementType.ANNOTATION_TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Qualifier
public @interface Autowired {

	@AliasFor(annotation = Qualifier.class, attribute = "value")
	String value() default "";

	@AliasFor(annotation = Qualifier.class, attribute = "value")
	String qualifier() default "";

	boolean required() default true;

}

---

Issue Links:

• Allow @Autowired to be declared on parameters [SPR-14057] #18629 Allow @Autowired to be declared on parameters
• Introduce autowiring support for individual handler method parameters [SPR-14056] #18628 Introduce autowiring support for individual handler method parameters

[spring-projects-issues]

Sam Brannen commented

This issue depends on #18630.

[spring-projects-issues]

Sam Brannen commented

For various reasons, the team has decided not to compose @Autowired with @Qualifier. I am therefore resolving this issue as Won't Fix.