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
JPA 同一个项目persistent.xml有多个PersistentUnit 时报错 问题： JPA 同一个项目persistent.xml有多个PersistentUnit 时报错 Fatal … Read More
JPA 事务中的自增id 问题： 代码如下，e1.getId() 不行 EntityManager em = **** EntityTransaction trans = em.getTransaction(); trans.begin(); em.persistence(e1); System.out.println(e1.getId());//not work e1. getId() is null e2.referId=e1.getId(); em.persistence(e2); trans.commit(); 12345678 EntityManager em = ****EntityTransaction trans = em.getTransaction();trans.begin();em.persistence(e1);System.out.println(e1.getId());//not work e1. getId() is nulle2.referId=e1.getId();em.persistence(e2);trans.commit(); … Read More
Maven JPA Fatal error compiling: java.lang.RuntimeException: javax.annotation.processing.FilerException: Attempt to recreate a file for type *** 问题： mvn clean assembly:assembly 时报错： Maven JPA Fatal er… Read More