第5章 データエンコーディングおよび MediaTypes

public interface Encoder {

   /**
    * Convert data in the read/write format to the storage format.
    *
    * @param content data to be converted, never null.
    * @return Object in the storage format.
    */
   Object toStorage(Object content);

   /**
    * Convert from storage format to the read/write format.
    *
    * @param content data as stored in the cache, never null.
    * @return data in the read/write format
    */
   Object fromStorage(Object content);

   /**
     * Returns the {@link MediaType} produced by this encoder or null if the storage format is not known.
     */
   MediaType getStorageFormat();
}