Map static field from different table in JPA

Our application is using a table to store application wide settings in a property table like this (using JPA):

public class Property {
    String key; // primary key
    String value;
}

One of our entities needs to have one of those properties, a base directory for file storage, (same one for ALL entities of this type) in a static field (it doesn't need to be static, but it would make sense).

public class FileEntity {
     public static String BASE_DIR;
     ...
}

There is no mapped relationship between those to entites yet and there is nothign to be used as a foreign key from any side. Is it possible anyway, to define a mapping which inserts the value of the Property with key="basedir" into the BASE_DIR attribute of the FileEntity?

BASE_DIR not being static would be kind of ok, but the content would still be the same for all instances of FileEntity.

Solution

Possibly not as elegant as you would have wished:

@Entity
public class FileEntity {

    private static String BASE_DIR;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

Have a property service with a @PostConstruct to initialise all your entities

@PostConstruct
public void init() {
    FileEntity.setBaseDir(propertyRepository.findByKey("key1").getValue());
}

After all the beans have been loaded the static fields on your entities will be set and belong to the class.