JPA出現(xiàn)錯(cuò)誤No identifier specified for en

問題描述

啟動(dòng)項(xiàng)目未成功，報(bào)錯(cuò)如下：

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-03-17 13:19:24.391|main|ERROR|org.springframework.boot.SpringApplication.reportFailure:858|Application run failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.AnnotationException: No identifier specified for entity: com.xxx.domain.Earnings
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1745)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:576)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:498)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1083)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:853)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:316)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248)
    at com.xxx.YoufanApplication.main(YoufanApplication.java:21)
Caused by: org.hibernate.AnnotationException: No identifier specified for entity: com.xxx.domain.Earnings
    at org.hibernate.cfg.InheritanceState.determineDefaultAccessType(InheritanceState.java:266)
    at org.hibernate.cfg.InheritanceState.getElementsToProcess(InheritanceState.java:211)
    at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:778)
    at org.hibernate.boot.model.source.internal.annotations.AnnotationMetadataSourceProcessorImpl.processEntityHierarchies(AnnotationMetadataSourceProcessorImpl.java:250)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess$1.processEntityHierarchies(MetadataBuildingProcess.java:231)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:274)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:904)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:935)
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:57)
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:390)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:377)
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1804)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1741)
    ... 16 common frames omitted
Disconnected from the target VM, address: '127.0.0.1:50341', transport: 'socket'

Process finished with exit code 1

首先從其中找到核心錯(cuò)誤描述：

Invocation of init method failed; nested exception is org.hibernate.AnnotationException: No identifier specified for entity: com.xxx.domain.Earnings

問題原因

在實(shí)體類com.xxx.domain.Earnings使用javax.persistence.Entity進(jìn)行注解就會(huì)自動(dòng)進(jìn)行表的DDL操作

使用hibernate的映射表的時(shí)候entity類是必須要主鍵的，否則就會(huì)報(bào)出這個(gè)異常：No identifier specified for entity

解決方案

import javax.persistence.*;
@Entity
public class Earnings {
? ? @Id
? ? @GeneratedValue(strategy = GenerationType.AUTO)
? ? Long id;
? ? // ...
}

使用@javax.persistence.Id進(jìn)行注解后，問題解決。

No identifier specified for entity: XXXX錯(cuò)誤

在運(yùn)行項(xiàng)目的時(shí)候報(bào)了下面的錯(cuò)誤：

by: org.hibernate.AnnotationException: No identifier specified for entity: com.example1.demo1.Entity.User
at org.hibernate.cfg.InheritanceState.determineDefaultAccessType(InheritanceState.java:266) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.cfg.InheritanceState.getElementsToProcess(InheritanceState.java:211) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:731) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.boot.model.source.internal.annotations.AnnotationMetadataSourceProcessorImpl.processEntityHierarchies(AnnotationMetadataSourceProcessorImpl.java:249) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess$1.processEntityHierarchies(MetadataBuildingProcess.java:222) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:265) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:861) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:888) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]

原因及其解決

這是因?yàn)樵趯?shí)體的getID方法上沒有加上此@Id注解，但是檢查了一次確實(shí)加上了，最后的解決辦法如下：

1.在數(shù)據(jù)庫表對(duì)應(yīng)實(shí)體（entity.java）的方法:getId()前加上該段文字注解

@Id
@GeneratedValue(strategy= GenerationType.AUTO)

2.是因?yàn)閕d注解引錯(cuò)了包

錯(cuò)誤的包路徑：

import org.springframework.data.annotation.Id;

正確的包路徑：

import javax.persistence.Id;

以上為個(gè)人經(jīng)驗(yàn)，希望能給大家一個(gè)參考，也希望大家多多支持腳本之家。

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