Multiple keys for @Cacheable

[petrp]

Is there a simple way how to use multiple arguments as keys for @Cacheable? For example, if I wanted to cache

@Cacheable(value="book", key="???")
public Book findBook(String author, String title,
                     boolean checkWarehouse, boolean includeUsed)

with key determined by both author and title.

I tried asking that on SO but without success.

Proposal: What about changing Cacheable's String key to String[] keys in a future version? I suppose the internal implementation could be easily modified to take care of that.

[Marten Deinum]

Have you read the (java)docs for @Cacheable? key is an expression (SpEL) so you can basically select what you want/use as a key by writing the correct expression...

[petrp]

Have you read the (java)docs for @Cacheable? key is an expression (SpEL) so you can basically select what you want/use as a key by writing the correct expression...

Of course I did. I managed to solve it by writing expressions like author.hashCode() + 31 * title.hashCode() or separating it into a helper function

public static int hashes(Object... args) {
    return java.util.Arrays(args).asList().hashCode();
}

and calling it like key="T(mypackage.MyHelperClass).hashes(author, title)".

Thinking about it, maybe a better solution would be to use a list instead of working with hash codes (I'd have to check if it works):

public static int list(Object... args) {
    return java.util.Arrays(args).asList();
}

and calling it like key="T(mypackage.MyHelperClass).list(author, title)".

But all this is very far from elegant and readable. The simple fact that I want to use two fields as the key is buried under a lot of boilerplate code. Is there a simpler solution I'm missing?

Thanks,
Petr