I have the following code. Because the @Id value is generated sequentially in my MariaDB, it's not safe: I need to expose it in the clients. That's why I want a unpredictable random @Id. How should I change the code?
@Entity public class Item implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; // Automatic generated value // other fields, getters, setters & constructors } If not satisfied with default generators, you can define your own generator in the following manner;
@Entity public class Item implements Serializable { @Id @GeneratedValue(generator = MyGenerator.generatorName) @GenericGenerator(name = MyGenerator.generatorName, strategy = "a.b.c.MyGenerator") private String id; // rest of the entity } And the generator itself;
public class MyGenerator implements IdentifierGenerator { public static final String generatorName = "myGenerator"; @Override public Serializable generate(SharedSessionContractImplementor sharedSessionContractImplementor, Object object) throws HibernateException { return UUID.randomUUID().toString().replace("-", ""); // or any other logic you'd like for generating unique IDs } } 
Using Hibernate and UUID identifiers
The UUID hex generator is the oldest UUID identifier generator and it’s registered under the “uuid” type. It can generate a 32 hexadecimal UUID string value (it can also use a separator) having the following pattern: 8{sep}8{sep}4{sep}8{sep}4.
@GeneratedValue(generator = "uuid") @GenericGenerator(name = "uuid", strategy = "uuid") @Column(columnDefinition = "CHAR(32)") @Id private String id; One thing of UUID identifiers which work for both MySQL(GenerationType.IDENTITY) and Oracle(GenerationType.SEQUENCE) for Hibernate auto key generation as one Entity class.
