CODEWITHSUNDEEP
javaspringcaching
Harshil Sharma
Harshil Sharma

Reputation: 2035

Creating Constants For Use In Annotation Fields

I'm incorporating cache in an existing spring project using Spring annotations. I have created this class for storing cache configuration -

public class CacheParams {

    public final String name;    
    public final int lifeTime;    
    public final TimeUnit lifeTimeUnit;    
    public final String key;

    public CacheParams(args here) {/*implementation here*/}
}

and this is how I intend to use it -

class FooDaoCache extends FooDaoImpl {

    private static final CacheParam USER_BY_ID_CACHE = new CacheParams(values here);

    @Override
    @Cacheable(cacheNames = USER_BY_ID_CACHE.name, key = USER_BY_ID_CACHE.key)
    public User getUser(int userId) {
        implementation here
    }
}

But this does not work as USER_BY_ID_CACHE will be created on compile time. If I simply create a string constant containing cache name I can successfully use it -

class FooDaoCache extends FooDaoImpl {
    private static final String CACHE_NAME = "baz";

    @Override
    @Cacheable(cacheNames = CACHE_NAME)
    public User getUser(int userId) {
        //implementation here
    }
}

Is there any way to deal with this or an alternate design? I need the class CacheParams because I have to perform other operations using cache name, lifetime etc in other parts of code too.

Upvotes: 1

Views: 2390

Answers (1)

J. Tennié
J. Tennié

Reputation: 348

CacheParam needs to be an enum or the name field needs to be a static final String.

Annotation return types may only be primitive types, enums, Strings, classes and arrays of these.

Upvotes: 2

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