How to generate Custom Id in JPA

Question

i want generate Custom Id in JPA it must be primary key of table. there are many examples to create Custom Id using hibernate like [this](https://stackoverflow.com/questions/31158509/how-to-generate-custom-id- using-hibernate-while-it-must-be-primary-key-of-table) i want same implementation but in JPA.The id must be alphanumeric like STAND0001

Thanks.

Answer

You can do it using GenericGenerator like this :

 @Entity
public class Client {

    @Id
    @GenericGenerator(name = "client_id", strategy = "com.eframe.model.generator.ClientIdGenerator")
    @GeneratedValue(generator = "client_id")  
    @Column(name="client_id")
    private String clientId;
}

and the custom generator class (will add prefix to the ID, you can make it do what you like):

public class ClientIdGenerator implements IdentifierGenerator {

@Override
public Serializable generate(SessionImplementor session, Object object)
        throws HibernateException {

    String prefix = "cli";
    Connection connection = session.connection();

    try {
        Statement statement=connection.createStatement();

        ResultSet rs=statement.executeQuery("select count(client_id) as Id from Client");

        if(rs.next())
        {
            int id=rs.getInt(1)+101;
            String generatedId = prefix + new Integer(id).toString();
            return generatedId;
        }
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return null;
}
}