From the spring documentation :

• Spring Cacheable Key Generator Example For Sale
• Spring Cacheable Keygenerator Example
• Spring Boot Cacheable Key Generator

@FunctionalInterface public interface KeyGenerator Cache key generator. Used for creating a key based on the given method (used as context) and its parameters. (Object target, Method method, Object. Params) Generate a key. @Cacheable also accepts a key attribute, which takes a SPEL expression and evaluates against the parameters, and uses that value as the key to store or retrieve from the cache. This overrides the KeyGenerator. Here are a few examples.

How can I specify @Cachable to use isbn and checkWarehouse as key?

1. Spring has a built-in EhCache cache manager, org.springframework.cache.ehcache.EhCacheManagerFactoryBean. This is suitable for most caching situations, but I have found defining a custom cache manager to be useful because it allows me to control the cache either programmatically, or with annotations, using the same cache.
2. Jun 29, 2017 Spring Boot cache with. Spring.cache.type=redis spring.redis.host=192. @CacheConfig — Class level annotation allows to specify global values for annotations like cache name or key generator.

Update: Current Spring cache implementation uses all method parameters as the cache key if not specified otherwise. If you want to use selected keys, refer to Arjan’s answer which uses SpEL list {#isbn, #includeUsed} which is the simplest way to create unique keys.

From Spring Documentation

The default key generation strategy changed with the release of Spring
4.0. Earlier versions of Spring used a key generation strategy that, for multiple key parameters, only considered the hashCode() of
parameters and not equals(); this could cause unexpected key
collisions (see SPR-10237 for background). Cisco ios generate ssh key. The new
‘SimpleKeyGenerator’ uses a compound key for such scenarios.

Before Spring 4.0

I suggest you to concat the values of the parameters in Spel expression with something like key='#checkWarehouse.toString() + #isbn.toString()'), I believe this should work as org.springframework.cache.interceptor.ExpressionEvaluator returns Object, which is later used as the key so you don’t have to provide an int in your SPEL expression.

As for the hash code with a high collision probability – you can’t use it as the key.

Someone in this thread has suggested to use T(java.util.Objects).hash(#p0,#p1, #p2) but it WILL NOT WORK and this approach is easy to break, for example I’ve used the data from SPR-9377 :

Spring Cacheable Key Generator Example For Sale

Both lines print -636517714 on my environment.

P.S. Actually in the reference documentation we have

I think that this example is WRONG and misleading and should be removed from the documentation, as the keys should be unique.

P.P.S. also see https://jira.springsource.org/browse/SPR-9036 for some interesting ideas regarding the default key generation.

I’d like to add for the sake of correctness and as an entertaining fact that using a secure cryptographic hash function like SHA256, due to the properties of such function IS possible for this task, but to compute it every time may be too expensive.

Spring Cacheable Keygenerator Example

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:

Of course, if many methods need this and you’re always using all parameters for your key, then one can also define a custom key generator that includes the class and method name:

…with:

You can use a Spring-EL expression, for eg on JDK 1.7:

Spring Boot Cacheable Key Generator

This will work

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