@Cacheable(value="books", key="T(someType).hash(#isbn)") 
public Book findBook(ISBN isbn, boolean checkWarehouse, boolean includeUsed)



	

After some limited testing with Spring 3.2, it seems one can use a SpEL list: {..., ..., ...}. This can also include null values. Spring passes the list as the key to the actual cache implementation. When using Ehcache, such will at some point invoke List#hashCode(), which takes all its items into account. (I am not sure if Ehcache only relies on the hash code.)

I use this for a shared cache, in which I include the method name in the key as well, which the Spring default key generator does not include. This way I can easily wipe the (single) cache, without (too much...) risking matching keys for different methods. Like:

@Cacheable(value="bookCache", 
  key="{ #root.methodName, #isbn?.id, #checkWarehouse }")
public Book findBook(ISBN isbn, boolean checkWarehouse) 
...

@Cacheable(value="bookCache", 
  key="{ #root.methodName, #asin, #checkWarehouse }")
public Book findBookByAmazonId(String asin, boolean checkWarehouse)

@Cacheable(value="bookCache", key="#checkwarehouse.toString().append(#isbn.toString())")


@Cacheable(value="bookCache", key="isbn + '_' + checkWarehouse + '_' + includeUsed")