如何在 Spring Boot 中正确映射 oneTomany 和 manyToone

Question

我有两个实体，它们与实体类有双向关系：

会议设置：

@Entity
@Table(name = "meeting_settings")
public class MeetingsSetting {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "meeting_name")
    private String meetingName;

    @Column(name = "meeting_url")
    private String meetingUrl;

    @Column(name = "meeting_pw")
    private String meetingPw;

    @OneToMany(mappedBy = "meetingsSetting", cascade = CascadeType.ALL)
    private Set<Date> dates = new HashSet<>();

    @OneToMany(mappedBy = "meetingsSetting", cascade = CascadeType.ALL)
    private List<Time> times = new ArrayList<>();

带配置类：

@Configuration
@PropertySource({"classpath:persistence-multiple-db.properties"})
@EnableJpaRepositories(
        basePackages = "com.cbc.coorporateblinddateservice.repositories.meetinsSetting",
        entityManagerFactoryRef = "meetingSettingEntityManager",
        transactionManagerRef = "meetingSettingTransactionManager"
)
public class MeetingSettingsConfig {

    @Autowired
    private Environment env;

    @Bean
    @Primary
    public LocalContainerEntityManagerFactoryBean meetingSettingEntityManager() {
        LocalContainerEntityManagerFactoryBean em
                = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(meetingSettingDataSource());
        em.setPackagesToScan(
                "com.cbc.coorporateblinddateservice.entities.meetinsSetting");

        HibernateJpaVendorAdapter vendorAdapter
                = new HibernateJpaVendorAdapter();
        em.setJpaVendorAdapter(vendorAdapter);
        HashMap<String, Object> properties = new HashMap<>();
        properties.put("hibernate.hbm2ddl.create",
                env.getProperty("meetingSetting.hibernate.hbm2ddl"));
        properties.put("hibernate.dialect",
                env.getProperty("hibernate.dialect"));
        em.setJpaPropertyMap(properties);

        return em;
    }

    @Primary
    @Bean
    public DataSource meetingSettingDataSource() {

        DriverManagerDataSource dataSource
                = new DriverManagerDataSource();
        dataSource.setDriverClassName(
                env.getProperty("meetingSetting.jdbc.driverClassName"));
        dataSource.setUrl(env.getProperty("meetingSetting.jdbc.url"));
        dataSource.setUsername(env.getProperty("meetingSetting.jdbc.user"));
        dataSource.setPassword(env.getProperty("meetingSetting.jdbc.pass"));
        dataSource.setSchema("coorporate_blinddate");

        return dataSource;
    }

    @Primary
    @Bean
    public PlatformTransactionManager meetingSettingTransactionManager() {

        JpaTransactionManager transactionManager
                = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(
                meetingSettingEntityManager().getObject());
        return transactionManager;
    }

和日期实体：

@Entity
@Table(name = "meeting_date")
public class Date {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "meeting_date")
    private String date;

    @OneToMany(mappedBy = "meetingDate", cascade = CascadeType.ALL)
    private List<Time> meetingTime = new ArrayList<>();

    @ManyToOne(targetEntity = MeetingsSetting.class)
    @JoinColumn(name = "meeting_settings_id", nullable = false)
    private MeetingsSetting meetingsSetting;

}

配置类：

@Configuration
@PropertySource({"classpath:persistence-multiple-db.properties"})
@EnableJpaRepositories(
        basePackages = "com.cbc.coorporateblinddateservice.repositories.dates",
        entityManagerFactoryRef = "meetingDateEntityManager",
        transactionManagerRef = "meetingDateTransactionManager"
)
public class MeetingDateConfig {

    @Autowired
    private Environment env;

    @Bean
    @Primary
    public LocalContainerEntityManagerFactoryBean meetingDateEntityManager() {
        LocalContainerEntityManagerFactoryBean em
                = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(meetingDateDataSource());
        em.setPackagesToScan(
                "com.cbc.coorporateblinddateservice.entities.dates");

        HibernateJpaVendorAdapter vendorAdapter
                = new HibernateJpaVendorAdapter();
        em.setJpaVendorAdapter(vendorAdapter);
        HashMap<String, Object> properties = new HashMap<>();
        properties.put("hibernate.hbm2ddl.create",
                env.getProperty("meetingDate.hibernate.hbm2ddl"));
        properties.put("hibernate.dialect",
                env.getProperty("hibernate.dialect"));
        em.setJpaPropertyMap(properties);

        return em;
    }

    @Primary
    @Bean
    public DataSource meetingDateDataSource() {

        DriverManagerDataSource dataSource
                = new DriverManagerDataSource();
        dataSource.setDriverClassName(
                env.getProperty("meetingDate.jdbc.driverClassName"));
        dataSource.setUrl(env.getProperty("meetingDate.jdbc.url"));
        dataSource.setUsername(env.getProperty("meetingDate.jdbc.user"));
        dataSource.setPassword(env.getProperty("meetingDate.jdbc.pass"));
        dataSource.setSchema("coorporate_blinddate");

        return dataSource;
    }

    @Primary
    @Bean
    public PlatformTransactionManager meetingDateTransactionManager() {

        JpaTransactionManager transactionManager
                = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(
                meetingDateEntityManager().getObject());
        return transactionManager;
    }

如果我知道尝试启动我的应用程序，我会收到以下错误：

Caused by: org.hibernate.AnnotationException: @OneToOne or @ManyToOne on com.cbc.coorporateblinddateservice.entities.dates.Date.meetingsSetting references an unknown entity: com.cbc.coorporateblinddateservice.entities.meetinsSetting.MeetingsSetting
    at org.hibernate.cfg.ToOneFkSecondPass.doSecondPass(ToOneFkSecondPass.java:100) ~[hibernate-core-5.4.31.Final.jar:5.4.31.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processEndOfQueue(InFlightMetadataCollectorImpl.java:1823) ~[hibernate-core-5.4.31.Final.jar:5.4.31.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processFkSecondPassesInOrder(InFlightMetadataCollectorImpl.java:1767) ~[hibernate-core-5.4.31.Final.jar:5.4.31.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1655) ~[hibernate-core-5.4.31.Final.jar:5.4.31.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:295) ~[hibernate-core-5.4.31.Final.jar:5.4.31.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:1224) ~[hibernate-core-5.4.31.Final.jar:5.4.31.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1255) ~[hibernate-core-5.4.31.Final.jar:5.4.31.Final]

我在这里查看了几篇建议更正实体注释的导入（Java.persistence，并通过 manyToone 设置 targetClass）以及完全像我一样执行此操作的示例，但没有一个对我有帮助。有人可以看看我的代码并告诉我可能有什么问题吗？

Answer 1

Hibernate 需要知道在哪里寻找实体类。

你在做em.setPackagesToScan("com.cbc.coorporateblinddateservice.entities.dates") 但是MeetingsSetting在com.cbc.coorporateblinddateservice.entities.meetinsSetting包中，所以你也需要扫描那个包。