Use field or parameter name as default value for @Qualifier [SPR-5152]

[spring-projects-issues]

Dave Syer opened SPR-5152 and commented

Use field or parameter name as default value for @Qualifier. E.g.

@Autowired
@Qualifier("requests")
private MessageChannel requests;

@Autowired
@Qualifier("replies")
private PollableChannel replies;

Would be replaced by

@Autowired
@Qualifier
private MessageChannel requests;

@Autowired
@Qualifier
private PollableChannel replies;

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Issue Links:

• @Autowired vs. @Resource [SPR-5579] #10250 @Autowired vs. @Resource

Referenced from: commits b85d457

1 votes, 1 watchers

[spring-projects-issues]

Dave Syer commented

Or...

@Autowired(type=AutowireType.BY_NAME)
private MessageChannel requests;

@Autowired(type=AutowireType.BY_NAME)
private PollableChannel replies;

(The AutowireType could be provided at the @Component level as well.)

[spring-projects-issues]

Dave Syer commented

Or even better...

@Autowired
private MessageChannel requests;

@Autowired
private PollableChannel replies;

So if there are multiple type-based matches the default would be look for a bean name.

[spring-projects-issues]

Juergen Hoeller commented

I've implemented the latter suggestion: @Autowired fields or method parameters take the field/parameter name into account as a default qualifier that resolves the ambiguity in case of multiple matches (effectively like if there was an @Qualifier annotation with the same value as the field/parameter name).

The use of the primary flag on a target bean still overrides this, though: i.e. if one of the matching candidates is marked primary, that one will be taken, even if another one happens to have a bean name that matches the field/parameter name. That's the only difference to the use of an explicit @Qualifier, which according to the standard algorithm narrows to all qualified instances first before selecting a primary candidate among those few in the narrowed set.

Juergen