springboot中@oneToMany双向映射的java问题

1 年，3 月 Questions & Answers 46

我试图使用spring boot和hibernate@OneToMany双向映射从MySql中的两个表中检索数据。但我也犯了这样的错误：没有为实体com指定标识符。大佛。春天阿普洛格。实体行动

请检查以下错误跟踪：


Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2020-03-14 18:56:59.251 ERROR 8200 --- [  restartedMain] o.s.boot.SpringApplication               : 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.dafe.spring.applogger.entity.Action
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1771) ~[spring-beans-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:593) ~[spring-beans-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1105) ~[spring-context-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) ~[spring-context-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.1.13.RELEASE.jar:2.1.13.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:744) [spring-boot-2.1.13.RELEASE.jar:2.1.13.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:391) [spring-boot-2.1.13.RELEASE.jar:2.1.13.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:312) [spring-boot-2.1.13.RELEASE.jar:2.1.13.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.1.13.RELEASE.jar:2.1.13.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1204) [spring-boot-2.1.13.RELEASE.jar:2.1.13.RELEASE]
    at com.dafe.spring.applogger.AppLoggerApplication.main(AppLoggerApplication.java:10) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_161]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_161]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_161]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_161]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.1.13.RELEASE.jar:2.1.13.RELEASE]
Caused by: org.hibernate.AnnotationException: No identifier specified for entity: com.dafe.spring.applogger.entity.Action
    at org.hibernate.cfg.InheritanceState.determineDefaultAccessType(InheritanceState.java:266) ~[hibernate-core-5.3.15.Final.jar:5.3.15.Final]
    at org.hibernate.cfg.InheritanceState.getElementsToProcess(InheritanceState.java:211) ~[hibernate-core-5.3.15.Final.jar:5.3.15.Final]
    at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:775) ~[hibernate-core-5.3.15.Final.jar:5.3.15.Final]
    at org.hibernate.boot.model.source.internal.annotations.AnnotationMetadataSourceProcessorImpl.processEntityHierarchies(AnnotationMetadataSourceProcessorImpl.java:250) ~[hibernate-core-5.3.15.Final.jar:5.3.15.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess$1.processEntityHierarchies(MetadataBuildingProcess.java:231) ~[hibernate-core-5.3.15.Final.jar:5.3.15.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:274) ~[hibernate-core-5.3.15.Final.jar:5.3.15.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:1215) ~[hibernate-core-5.3.15.Final.jar:5.3.15.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1246) ~[hibernate-core-5.3.15.Final.jar:5.3.15.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) ~[spring-orm-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) ~[spring-orm-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:391) ~[spring-orm-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:378) ~[spring-orm-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) ~[spring-orm-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1830) ~[spring-beans-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1767) ~[spring-beans-5.1.14.RELEASE.jar:5.1.14.RELEASE]
    ... 21 common frames omitted

错误指向的类在下面，但我似乎不知道问题出在哪里。下面是本网站的网址。大佛。春天阿普洛格。实体行动类：

package com.dafe.spring.applogger.entity;

import java.sql.Timestamp;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

import org.springframework.data.annotation.Id;

@Entity
@Table(name="action")
public class Action {

    //declare & annotate your fields
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="id")
    private int id;

@Column(name="time")
    private Timestamp logTime;

@Column(name="type")
    private String logType;

@Column(name="log_id")
    private int userLogId;

@ManyToOne
@JoinColumn(name="log_id")
private UserLog userLog;

public Action(int id, Timestamp logTime, String logType, int userLogId, UserLog userLog) {
    this.id = id;
    this.logTime = logTime;
    this.logType = logType;
    this.userLogId = userLogId;
    this.userLog = userLog;
}

    //create and generate constructor
    public Action() {

    }

    public Action(Timestamp logTime, String logType, int userLogId) {
        this.logTime = logTime;
        this.logType = logType;
        this.userLogId = userLogId;
    }


    //generate getters and setters

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Timestamp getLogTime() {
        return logTime;
    }

    public void setLogTime(Timestamp logTime) {
        this.logTime = logTime;
    }

    public String getLogType() {
        return logType;
    }

    public void setLogType(String logType) {
        this.logType = logType;
    }

    public int getLogId() {
        return userLogId;
    }

    public void setLogId(int logId) {
        this.userLogId = logId;
    }


    public UserLog userLog() {
        return userLog;
    }

    public void setLogs(UserLog userLog) {
        this.userLog = userLog;
    }

    //generate toString 

    @Override
    public String toString() {
        return "Action [id=" + id + ", logTime=" + logTime + ", logType=" + logType + ", userLogId=" + userLogId + "]";
    }


}

action类应该从数据库中获取数据，并且与类UserLog具有外键关系

package com.dafe.spring.applogger.entity;

import java.util.ArrayList;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name="log")
public class UserLog {

    //define field

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="id")
    private int id;

    @Column(name="user_id")
    private String userId;

    @Column(name="session_id")
    private String sessionId;

    @OneToMany(mappedBy="log",cascade=CascadeType.ALL)
        private ArrayList<Action>action;
    //define constructors

    public UserLog(String userId, String sessionId) {
        this.userId = userId;
        this.sessionId = sessionId;
    }
    //define getters and setters


    public int getId() {
        return id;
    }


    public void setId(int id) {
        this.id = id;
    }


    public String getUserId() {
        return userId;
    }


    public void setUserId(String userId) {
        this.userId = userId;
    }


    public String getSessionId() {
        return sessionId;
    }


    public void setSessionId(String sessionId) {
        this.sessionId = sessionId;
    }

    public ArrayList<Action> getAction() {
        return action;
    }


    public void setAction(ArrayList<Action> action) {
        this.action = action;
    }

    //convenience method for Action
    public void addAction(Action tempAction) {

        if (action == null) {
        action = new ArrayList<>();
        }

        action.add(tempAction);
    }


    //define toString

    @Override
    public String toString() {
        return "Log [id=" + id + ", userId=" + userId + ", sessionId=" + sessionId + "]";
    }



}

请帮我找出问题和可能的解决办法。谢谢

共 (2) 个答案

# 1 楼答案
我认为一个问题与此映射有关：
```
@OneToMany(mappedBy="log",cascade=CascadeType.ALL)
        private ArrayList<Action>action;
```
mappedBy指向“拥有”端的属性名称。所以在您的例子中，您应该指定动作类中定义的mappedBy="userLog"
```
@ManyToOne
@JoinColumn(name="log_id")
private UserLog userLog;
```
# 2 楼答案
您从错误的包中导入了Id。当为@Id导入与javax.persistance.Id ;不同的库时，可能会引发此错误

所以改变
```
import org.springframework.data.annotation.Id;
```
到
```
import javax.persistence.Id
```
参考this thread

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springboot中@oneToMany双向映射的java问题

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