JPA Resolved [java.lang.IllegalArgumentException: Id must be assignable to Serializable: null] 问题： JPA Entity 如下 @Table (name= "EMP") @Inheritance @DiscriminatorColumn (name="EMP TPE") public abstract class Employee {...} @Entity @DiscriminatorValue ("CEmp") public class contractemployee extenas Employee{...} @MappedSuperclass public abstract class CompanyEmployee extends Employee {...} @Entity @DiscriminatorValue ("FTEmp") public class FullTimeEmployee extenas companyemployee {....} @Entity (name= "PTEmp") public class PartTimeEmployee extends CompanyEmployee {....} 123456789101112131415161718 @Table (name= "EMP") @Inheritance@DiscriminatorColumn (name="EMP TPE") public abstract class Employee {...} @Entity@DiscriminatorValue ("CEmp")public class contractemployee extenas Employee{...} @MappedSuperclasspublic abstract class CompanyEmployee extends Employee {...} @Entity@DiscriminatorValue ("FTEmp")public class FullTimeEmployee extenas companyemployee {....} @Entity (name= "PTEmp")public class PartTimeEmployee extends CompanyEmployee {....} &nbs… Read More