java - Spring Boot hibernate 时关系映射中的错误

我正在使用Spring Boot 1.5.9.RELEASE，并且在EntityManagerFactory中遇到编译时错误。我可以在没有外键的表中进行CRUD操作，而在有外键的表中，pproject甚至不会编译有关EntityManagerFactory的抱怨。我正在使用Intellij IDEA 2017.3。以下是我的模型课：

package com.example.demo.Model;

import javax.persistence.*;

@Entity
@Table(name = "student")
public class Student {

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

    @Column(name = "sname")
    private String name;

    @Column(name = "sroll")
    private int roll;

    @ManyToOne
    @JoinColumn(name = "cid", table = "college")
    private College college;

    public int getId() {
        return id;
    }

    public College getCollege() {
        return college;
    }

    public void setCollege(College college) {
        this.college = college;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getRoll() {
        return roll;
    }

    public void setRoll(int roll) {
        this.roll = roll;
    }
}

    package com.example.demo.Model;

    import javax.persistence.*;
    import java.util.List;

    @Entity
    @Table(name = "college")
    public class College {

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

    @Column(name = "cname")
    private String name;

    @OneToMany(targetEntity = Student.class, mappedBy = "college",
            cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private List<Student> studentList;

    public List<Student> getStudentList() {
        return studentList;
    }

    public void setStudentList(List<Student> studentList) {
        this.studentList = studentList;
    }

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

我的DAO类如下：

package com.example.demo.DAO;

import com.example.demo.Model.College;
import org.springframework.stereotype.Repository;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceUnit;
import javax.transaction.Transactional;

@Transactional
@Repository
public class CollegeDAO {

    @PersistenceUnit
    EntityManagerFactory emf;

    public boolean add(College college) {

        EntityManager em = emf.createEntityManager();
        em.getTransaction().begin();
        em.persist(college);
        em.getTransaction().commit();

        return true;
    }
}

package com.example.demo.DAO;


import com.example.demo.Model.Student;
import org.apache.tomcat.jni.Local;
import org.springframework.stereotype.Repository;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceUnit;
import javax.transaction.Transactional;
import java.util.List;

@Transactional
@Repository
public class StudentDAO {

    @PersistenceUnit
    private EntityManagerFactory emf;

    public boolean add(Student student) {

        EntityManager em = emf.createEntityManager();
        em.getTransaction().begin();
        em.persist(student);
        em.getTransaction().commit();

        return true;
    }
}

错误堆栈如下：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.AnnotationException: Cannot find the expected secondary table: no college available for com.example.demo.Model.Student
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1080) ~[spring-context-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:857) ~[spring-context-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543) ~[spring-context-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at com.example.demo.DemoApplication.main(DemoApplication.java:10) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_151]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_151]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_151]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_151]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-1.5.10.RELEASE.jar:1.5.10.RELEASE]
Caused by: org.hibernate.AnnotationException: Cannot find the expected secondary table: no college available for com.example.demo.Model.Student
    at org.hibernate.cfg.Ejb3Column.getJoin(Ejb3Column.java:452) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.cfg.Ejb3Column.getTable(Ejb3Column.java:423) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.cfg.AnnotationBinder.bindManyToOne(AnnotationBinder.java:2854) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:1763) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.cfg.AnnotationBinder.processIdPropertiesIfNotAlready(AnnotationBinder.java:911) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:738) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.boot.model.source.internal.annotations.AnnotationMetadataSourceProcessorImpl.processEntityHierarchies(AnnotationMetadataSourceProcessorImpl.java:245) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess$1.processEntityHierarchies(MetadataBuildingProcess.java:222) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:265) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:847) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:874) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:60) ~[spring-orm-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:360) ~[spring-orm-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:382) ~[spring-orm-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:371) ~[spring-orm-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:336) ~[spring-orm-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1687) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1624) ~[spring-beans-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    ... 21 common frames omitted

最佳答案

问题出在您的Student类中：

@ManyToOne
@JoinColumn(name = "cid", table = "college")
private College college;

您试图将cid添加为college表中的列。这没有任何意义，因为在一所大学里有更多的学生。 JoinColumn应该位于student表中，或者位于将学生ID与大学ID相结合的辅助表中，而不是在college表中。一种解决方案是删除table = "college"或将其更改为辅助联接表的新名称。