How to create custom id generator for primary key in springboot

@IdGeneratorType(YourCustomGenerator.class)
@Retention(RUNTIME) @Target({METHOD,FIELD})
public @interface YourCustomGeneration {
  //you can
}

@IdGeneratorType(YourCustomGenerator.class)
@Retention(RUNTIME) @Target({METHOD,FIELD})
public @interface YourCustomGeneration {
  //you can
}

//in your entity
@Id
@YourCustomGeneration
private YourIdType yourId;

//in your entity
@Id
@YourCustomGeneration
private YourIdType yourId;

public class CustomSequenceGenerator implements BeforeExecutionGenerator {
     public CustomSequenceGenerator(YourCustomGeneration annotation, Member annotatedMember,
                                    CustomIdGeneratorCreationContext context) {
         //you can do initialization logic here
     }
    @Override
    public Object generate​(SharedSessionContractImplementor session, Object owner, Object currentValue, EventType eventType){
      //logic to generate your key
      return yourNewKey;
    }
}

public class CustomSequenceGenerator implements BeforeExecutionGenerator {
     public CustomSequenceGenerator(YourCustomGeneration annotation, Member annotatedMember,
                                    CustomIdGeneratorCreationContext context) {
         //you can do initialization logic here
     }
    @Override
    public Object generate​(SharedSessionContractImplementor session, Object owner, Object currentValue, EventType eventType){
      //logic to generate your key
      return yourNewKey;
    }
}

con = session.getJdbcConnectionAccess().obtainConnection();
            stmt = con.createStatement();
            
            
            String sql_query = "SELECT MATRICULE_SEQ.NEXTVAL FROM DUAL";
            ResultSet result = stmt.executeQuery(sql_query);
            
            if (result.next()) {
                key = result.getInt(1);  
            }

con = session.getJdbcConnectionAccess().obtainConnection();
            stmt = con.createStatement();
            
            
            String sql_query = "SELECT MATRICULE_SEQ.NEXTVAL FROM DUAL";
            ResultSet result = stmt.executeQuery(sql_query);
            
            if (result.next()) {
                key = result.getInt(1);  
            }

try(SomeAutoCloseable objectYouWantToClose = ...) {

}//objectYouWantToClose will be closed automatically here

try(SomeAutoCloseable objectYouWantToClose = ...) {

}//objectYouWantToClose will be closed automatically here

SomeAutoCloseable objectYouWantToClose = ...
try {

} finally {
  if(objectYouWantToClose != null) {
    try {
       objectYouWantToClose.close();
    } catch(Exception e) {
       if (EXCEPTION HAS BEEN THROWN IN TRY BLOCK) {
          thatException.addSuppressed(e);
          throw thatException;
       }
       throw e;
    }
  }
}

SomeAutoCloseable objectYouWantToClose = ...
try {

} finally {
  if(objectYouWantToClose != null) {
    try {
       objectYouWantToClose.close();
    } catch(Exception e) {
       if (EXCEPTION HAS BEEN THROWN IN TRY BLOCK) {
          thatException.addSuppressed(e);
          throw thatException;
       }
       throw e;
    }
  }
}

    public Serializable generate(SharedSessionContractImplementor session, Object object) {
        
    } 

    public Serializable generate(SharedSessionContractImplementor session, Object object) {
        
    } 

public class PrefixIdGenerator implements IdentifierGenerator {
    private String prefix;
    private String sequenceName;

    public PrefixIdGenerator(PrefixGenerator config, Member annotatedMember, CustomIdGeneratorCreationContext context) {
        prefix = config.prefix();
        sequenceName = config.sequenceName();
    }

    @Override
    public Serializable generate(SharedSessionContractImplementor session, Object object) {
        try (session.getJdbcConnectionAccess().obtainConnection()) {

        }
    }
}

public class PrefixIdGenerator implements IdentifierGenerator {
    private String prefix;
    private String sequenceName;

    public PrefixIdGenerator(PrefixGenerator config, Member annotatedMember, CustomIdGeneratorCreationContext context) {
        prefix = config.prefix();
        sequenceName = config.sequenceName();
    }

    @Override
    public Serializable generate(SharedSessionContractImplementor session, Object object) {
        try (session.getJdbcConnectionAccess().obtainConnection()) {

        }
    }
}

public class PrefixIdGenerator implements IdentifierGenerator {
    private String prefix;
    private String sequenceName;

    public PrefixIdGenerator(PrefixGenerator config, Member annotatedMember, CustomIdGeneratorCreationContext context) {
        prefix = config.prefix();
        sequenceName = config.sequenceName();
    }

    @Override
    public Object generate(SharedSessionContractImplementor session, Object object) {
        String key = prefix;
        String query = "SELECT ?.NEXTVAL FROM dual;";
        try (Connection con = session.getJdbcConnectionAccess().obtainConnection() ; PreparedStatement pstm = con.prepareStatement(query)) {
            pstm.setString(0, sequenceName);
            ResultSet result = pstm.executeQuery();
            if (result.next()) {
                key = key + result.getInt(1);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return key;
    }
}

public class PrefixIdGenerator implements IdentifierGenerator {
    private String prefix;
    private String sequenceName;

    public PrefixIdGenerator(PrefixGenerator config, Member annotatedMember, CustomIdGeneratorCreationContext context) {
        prefix = config.prefix();
        sequenceName = config.sequenceName();
    }

    @Override
    public Object generate(SharedSessionContractImplementor session, Object object) {
        String key = prefix;
        String query = "SELECT ?.NEXTVAL FROM dual;";
        try (Connection con = session.getJdbcConnectionAccess().obtainConnection() ; PreparedStatement pstm = con.prepareStatement(query)) {
            pstm.setString(0, sequenceName);
            ResultSet result = pstm.executeQuery();
            if (result.next()) {
                key = key + result.getInt(1);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return key;
    }
}

String query = "SELECT ?.NEXTVAL FROM dual;";

String query = "SELECT ?.NEXTVAL FROM dual;";

import org.hibernate.engine.spi.SharedSessionContractImplementor;
import org.hibernate.id.IdentifierGenerator;

public interface CustomIdentifierGenerator extends IdentifierGenerator {


    void checkSequences() {
       // implementation, go in database, get all the sequence_name, check if there is one we don't know about, if that's the case then add it to a class that will contain them
    };


    @Override
    default Object generate(SharedSessionContractImplementor session, Object object) {

        checkSequences();
        

        return generateIdentifier(session, object);
    }

    Object generateIdentifier(SharedSessionContractImplementor session, Object object);
}

import org.hibernate.engine.spi.SharedSessionContractImplementor;
import org.hibernate.id.IdentifierGenerator;

public interface CustomIdentifierGenerator extends IdentifierGenerator {


    void checkSequences() {
       // implementation, go in database, get all the sequence_name, check if there is one we don't know about, if that's the case then add it to a class that will contain them
    };


    @Override
    default Object generate(SharedSessionContractImplementor session, Object object) {

        checkSequences();
        

        return generateIdentifier(session, object);
    }

    Object generateIdentifier(SharedSessionContractImplementor session, Object object);
}

|sequence_name|current_index|

|sequence_name|current_index|

public interface CustomIdentifierGenerator extends IdentifierGenerator {

    private final IdentifierGenerator delegate = new OrderedSequenceGenerator();//or similar
  
    @Override
    default Object generate(SharedSessionContractImplementor session, Object object) {

        return "PER" + delegate.generate(session, object);
    }
}

public interface CustomIdentifierGenerator extends IdentifierGenerator {

    private final IdentifierGenerator delegate = new OrderedSequenceGenerator();//or similar
  
    @Override
    default Object generate(SharedSessionContractImplementor session, Object object) {

        return "PER" + delegate.generate(session, object);
    }
}

public interface CustomIdentifierGenerator extends IdentifierGenerator {

    private final IdentifierGenerator delegate = new OrderedSequenceGenerator();//or similar
  
    @Override
    default Object generate(SharedSessionContractImplementor session, Object object) {
        if (object instanceof String s && s.startsWith("PER")) {
            object = Integer.parseInt(s.substring(3));
        }
        return "PER" + delegate.generate(session, object);
    }
}

public interface CustomIdentifierGenerator extends IdentifierGenerator {

    private final IdentifierGenerator delegate = new OrderedSequenceGenerator();//or similar
  
    @Override
    default Object generate(SharedSessionContractImplementor session, Object object) {
        if (object instanceof String s && s.startsWith("PER")) {
            object = Integer.parseInt(s.substring(3));
        }
        return "PER" + delegate.generate(session, object);
    }
}

public class PrefixedSequenceIdGenerator implements IdentifierGenerator {
    private String prefix;
    private SequenceStyleGenerator sequenceGenerator;

    public PrefixedSequenceIdGenerator(PrefixGenerator config, Member annotatedMember, CustomIdGeneratorCreationContext context) {
        this.prefix = config.prefix();

        // Initialize the sequence generator with the sequence name from the annotation
        this.sequenceGenerator = new SequenceStyleGenerator();
        this.sequenceGenerator.initialize(config.sequenceName(), context.getServiceRegistry());
    }

    @Override
    public Object generate(SharedSessionContractImplementor session, Object object) {
        // Generate the next sequence value using the sequence generator
        Number sequenceValue = (Number) sequenceGenerator.generate(session, object);

        // Return the concatenated prefix and sequence value
        return prefix + sequenceValue.toString();
    }
}

public class PrefixedSequenceIdGenerator implements IdentifierGenerator {
    private String prefix;
    private SequenceStyleGenerator sequenceGenerator;

    public PrefixedSequenceIdGenerator(PrefixGenerator config, Member annotatedMember, CustomIdGeneratorCreationContext context) {
        this.prefix = config.prefix();

        // Initialize the sequence generator with the sequence name from the annotation
        this.sequenceGenerator = new SequenceStyleGenerator();
        this.sequenceGenerator.initialize(config.sequenceName(), context.getServiceRegistry());
    }

    @Override
    public Object generate(SharedSessionContractImplementor session, Object object) {
        // Generate the next sequence value using the sequence generator
        Number sequenceValue = (Number) sequenceGenerator.generate(session, object);

        // Return the concatenated prefix and sequence value
        return prefix + sequenceValue.toString();
    }
}