Cache object only if it is Serializable

Question

I have enabled Caching by using @Cacheable annotation on a method which has the following declaration:

@Cacheable(value = "myCache", key = "#t+ '_' + #key", condition = "#key != null")
public <T> T get(String t, VendorProperty<T> key, T defaultValue) {
    return get(t, key).orElse(default_value);
}

However, this throws NotSerializableException if the object it is trying to cache is not Serializable (for example: DateTimeFormatter).

I was wondering if it is possible to cache objects only when the object is Serializable to avoid this exception.

I am using memcache to cache the objects using simple-spring-memcache library.

PS: I can't implement the Serializable interface as DateTimeFormatter is a predefined class.

Answer 1

The suggestion above won't work. #root.target is the target object being executed (in this case the service object). So it will appear to work because the service object is not serializable and so the object in question won't be cached but neither will anything else.

You need to leverage the "unless" condition using the result variable:

@Cacheable(value = "myCache", 
           key = "#t+ '_' + #key", 
           condition = "#key != null"
           unless="!(#result instanceof T(java.io.Serializable))")