Support placeholders in @Resource annotation configurations [SPR-5656]

[spring-projects-issues]

nicolas de loof opened SPR-5656 and commented

Using @Resource is a nice option to get dependency injection. You just can't get support for propertyPlaceholder. For example, getting some configuration URL I'd like to write :

@Resource( name="${my.server.URL}" )
private URL serverUrl;

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Affects: 2.5.6

Referenced from: commits 859497b

[spring-projects-issues]

Juergen Hoeller commented

Good idea! We're supporting placeholders for @Value values in 3.0 M3 already, so supporting them for @Resource names as well makes a lot of sense.

Juergen

[spring-projects-issues]

nicolas de loof commented

The changes in #955 only support Bean injection (bean ID beeing configurable), not value injection with @Resource annotation. I'd like to write the following and get Spring use type conversion to resolve the placeholder as URL.

@Resource( name="${my.server.URL}" )
private URL serverUrl;

with properties :
my.server.URL = http://www.myserver/foo

But maybe the @Resource annotation is not designed for such use-case. Is the @Value annotation a new Spring3 class ? Is there something comparable in commons-annotation (I'd like to be framework agnostic)

[spring-projects-issues]

Juergen Hoeller commented

Ah good point, I missed your original intent there.

However, @Resource is not really designed for this indeed... It's a resource object lookup mechanism based on resource names. Using placeholders will only affect the name part, with the lookup still happening.

@Value is designed for resolving a value (through EL and/or placeholders in 3.0 M3) and injecting it right away. It is Spring specific but it seems to be exactly what you need. I'm not aware of a common annotation with similar semantics... except possibly for JSF 2.0's @ManagedProperty annotation (which does not support placeholders but rather just EL, though).

Juergen