how to prevent a return value from cache to be changed in spring cacheable

Question

i\'m working around spring 3.1 annotation cache with ehcache as a cache implement.

a method with return value like this

@Cacheable(\"cache\")
public          


        

Answer 1

I had the same problem with the spring cache. I didn't want to receive the same java objects from the cache.

In my case i want to cache big java objects with many fields and so on. So it is very painful to copy all the data classes with deep copy. I read the article about copy java objects with serialization.

http://www.javaworld.com/article/2077578/learn-java/java-tip-76--an-alternative-to-the-deep-copy-technique.html

This brought me to the idea to cache only the serialized data. Every time a object is read from the cache it is deserialized.

For the serialization i used apache commons helper methods

@Override
public SerializedQuestions readUserQuestion(UID questionId, Locale locale) {
 byte[] serializedData = readCachedUserQuestion(questionId, locale);
 Object deserializedobject = org.apache.commons.lang.SerializationUtils.deserialize(serializedData);
 return (SerializedQuestions) deserialize;
}

@Override
@Cacheable(value = SpringCacheKeys.USER_QUESTION_CACHE)
  public byte[] readCachedUserQuestion(UID questionId, Locale locale) {

  //read object from db
  SerializedQuestions questions = new SerializedQuestions()

  return org.apache.commons.lang.SerializationUtils.serialize(questions);
}

It depends on the spring configuration if the call to readCachedUserQuestion could be in the same class or not. Per default only extern calls to a method are cached.