全局配置Hibernate以使用GenerationType.IDENTITY

Question

Since Spring Boot 2 use Hibernate 5 the @GeneratedValue default strategy GenerationType.AUTO for my MySQL 5.7 database results in GenerationType.SEQUENCE emulated in a separate table, since MySQL 5.7 doesn't support sequences.

I want all of my tables' primary ids to be generated using GenerationType.IDENTITY .

Is there a global way to set this to be the default strategy, so I don't explicitly have to select the GenerationType.IDENTITY strategy each time I use @GeneratedValue on a field?

Answer 1

An easy way to use the same generator by all your entities is to have a @MappedSuperclass that defines the @Id field and uses what generation strategy you wish, then extending that class in your entities.

You can additionally define other attributes besides the primary key you want your entities to have. You can also define additional @MappedSuperclass classes if you want to have different "types" of entities, ie ones with just the pk defined, or with additional fields like created or updated .

@MappedSuperclass
public class PKEntity {

    @Id
    @GenericGenerator(name="universal", etc. etc. etc.)
    @GeneratedValue(generator="universal")
    private Long id;

    // Possibly more common columns your entities have
}

Answer 2

You could try creating your own annotation and using it instead of @GeneratedValue

import javax.persistence.GenerationType;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.METHOD, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface CustomGeneratedValue {
    GenerationType strategy() default GenerationType.IDENTITY;

    String generator() default "";
}