Request: lazy-init or 'only-if-needed' option for stereotype @Component source-annotated component-scan definitions [SPR-5662]

[spring-projects-issues]

Gordon Mohr opened SPR-5662 and commented

I'd like to be able to mark @Component-annotated classes to be instantiated and available for autowiring only if necessary to fill any required properties.

That is, even if 'singleton' and discovered by the package-scan, they aren't instantiated until needed. ('prototype' doesn't work because I still want only one instance if referenced twice.)

A 'lazy-init' flag for the @Component annotation would just about do the trick. Even more convenient would be some sort of 'only-if-needed' flag, which would also prevent the presence of the scan-discovered bean-definition from interfering (by being the second of the same type) with any definition explicitly included being used to satisfy a needs-one autowire-by-type situation. (Another idea along the same lines: allow specification of a recommended name for source-discovered @Components, so they could be autowired by name, too.)

(My initial request for this sort of functionality in the forums: http://forum.springsource.org/showthread.php?p=235027#post235027 )

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Affects: 2.5.6

Issue Links:

• Support use of @Primary and @Lazy during component-scanning [SPR-5629] #10300 Support use of @Primary and @Lazy during component-scanning

[spring-projects-issues]

Juergen Hoeller commented

We are introducing an @Lazy annotation in 3.0 M3 now. I hope that does the trick...

A default-lazy-init flag at the <beans> level will also affect component-scan instructions within its file. That should work in Spring 2.5.x already.

Juergen