java - 映射 @Entity 时出现 UnsatisfiedDependencyException beancreationerror

Question

我正在尝试使用 MySql 实现 Hibernate spring mvc 项目，但在使用 @Entity 映射我的 Book 类时遇到问题。 MySql 服务器与 Author.java 一起工作得很好，但是当我将 @Entity 映射到 Book 类时，我得到了 HTTP Status 500 代码。

认为问题在于 hibernate 接受表的方式，并且在我的 sessionFactory session 期间没有初始化名为 Book 的表。 hibernate 配置仅适用于我的 Author.java 类。

也许问题在于书籍类引用了我的作者？

public class Book {

    private long ISBN;
    private String title;
    private String releaseYear;
    private Author author;

错误行: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'homeController': Unsatisfied dependency expressed through field 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [no/package/config/HibernateConfig.class]: Invocation of init method failed; nested exception is org.hibernate.MappingException: Could not determine type for: my.package.model.Author, at table: Book, for columns: [org.hibernate.mapping.Column(author)]

--错误代码--

   Type Exception Report

Message Servlet.init() for servlet [dispatcher] threw exception

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception

javax.servlet.ServletException: Servlet.init() for servlet [dispatcher] threw exception
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.lang.Thread.run(Thread.java:748)
Root Cause

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'homeController': Unsatisfied dependency expressed through field 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [no/package/config/HibernateConfig.class]: Invocation of init method failed; nested exception is org.hibernate.MappingException: Could not determine type for: my.package.model.Author, at table: Book, for columns: [org.hibernate.mapping.Column(author)]
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:587)
    org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:91)
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:373)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1344)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
    org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312)
    org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310)
    org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:760)
    org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868)
    org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549)
    org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:677)
    org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:545)
    org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:499)
    org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:172)
    javax.servlet.GenericServlet.init(GenericServlet.java:158)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.lang.Thread.run(Thread.java:748)
Root Cause

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [no/package/config/HibernateConfig.class]: Invocation of init method failed; nested exception is org.hibernate.MappingException: Could not determine type for: my.package.model.Author, at table: Book, for columns: [org.hibernate.mapping.Column(author)]
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1710)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:583)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
    org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312)
    org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310)
    org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
    org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:251)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1065)
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:584)
    org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:91)
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:373)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1344)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
    org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312)
    org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310)
    org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:760)
    org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868)
    org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549)
    org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:676)
    org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:545)
    org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:499)
    org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:172)
    javax.servlet.GenericServlet.init(GenericServlet.java:158)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.lang.Thread.run(Thread.java:748)
Root Cause

org.hibernate.MappingException: Could not determine type for: my.package.model.Author, at table: Book, for columns: [org.hibernate.mapping.Column(author)]
    org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:455)
    org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:422)
    org.hibernate.mapping.Property.isValid(Property.java:226)
    org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:597)
    org.hibernate.mapping.RootClass.validate(RootClass.java:265)
    org.hibernate.boot.internal.MetadataImpl.validate(MetadataImpl.java:329)
    org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:459)
    org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:710)
    org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:726)
    org.springframework.orm.hibernate5.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:535)
    org.springframework.orm.hibernate5.LocalSessionFactoryBean.afterPropertiesSet(LocalSessionFactoryBean.java:519)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1769)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1706)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:583)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
    org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312)
    org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310)
    org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
    org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:251)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1065)
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:584)
    org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:91)
    org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:373)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1344)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
    org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312)
    org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310)
    org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
    org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:760)
    org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868)
    org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549)
    org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:676)
    org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:545)
    org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:499)
    org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:172)
    javax.servlet.GenericServlet.init(GenericServlet.java:158)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)

--HibernateConfig.java--

package my.package.config;

import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate5.HibernateTransactionManager;
import org.springframework.orm.hibernate5.LocalSessionFactoryBean;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.sql.DataSource;
import java.util.Properties;

@Configuration
@EnableTransactionManagement
@ComponentScan({"my.package"})
@PropertySource(value = {"classpath:application.properties"})
public class HibernateConfig {
        @Autowired
        private Environment environment;

        @Bean
        public LocalSessionFactoryBean sessionFactory() {
                LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
                sessionFactory.setDataSource(dataSource());
                sessionFactory.setPackagesToScan(new String[]{"my.package"}); 
                sessionFactory.setHibernateProperties(hibernateProperties());
                return sessionFactory;
        }

        @Bean
        public DataSource dataSource() {
                DriverManagerDataSource dataSource = new DriverManagerDataSource();
                dataSource.setDriverClassName(environment.getRequiredProperty("jdbc.driverClassName"));
                dataSource.setUrl(environment.getRequiredProperty("jdbc.url"));
                dataSource.setUsername(environment.getRequiredProperty("jdbc.username"));
                dataSource.setPassword(environment.getRequiredProperty("jdbc.password"));
                return dataSource;
        }

        private Properties hibernateProperties() {
                Properties properties = new Properties();
                properties.put("hibernate.dialect", environment.getRequiredProperty("hibernate.dialect"));
                properties.put("hibernate.show_sql", environment.getRequiredProperty("hibernate.show_sql"));
                properties.put("hibernate.format_sql", environment.getRequiredProperty("hibernate.format_sql"));
                properties.put("hibernate.hbm2ddl.auto", environment.getRequiredProperty("hibernate.hbm2ddl.auto"));
                return properties;
        }

        @Bean
        @Autowired
        public HibernateTransactionManager transactionManager(SessionFactory s) {
                HibernateTransactionManager txManager = new HibernateTransactionManager();
                txManager.setSessionFactory(s);
                return txManager;
        }
}

--Homecontroller.java--

package my.package.controller;

import com.fasterxml.classmate.AnnotationConfiguration;
import my.package.model.Author;
import my.package.model.Book;
import org.hibernate.SessionFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.ui.Model;
import java.util.List;
import java.util.LinkedList;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMethod;import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;

import javax.transaction.Transactional;
import java.util.List;



import javax.transaction.Transactional;


@Controller
public class HomeController {
        List<Author> authorList;
        List<Book> bookList;
        @Autowired
        SessionFactory sessionFactory;
        Boolean started = false; // for initializing Lists from hibernate.

        //RequestMapping for booklist, authorlist, add book, add author


        // , edit book, delete book.

        // menu for each other request.
        @Transactional
        @RequestMapping("/")
        public String home(){

                if (!started)
                {
                        authorListUpdate();
                        //bookListUpdate();
                        //bookList = new LinkedList<Book>();

                        started = true;
                }
                return "index";
        }

        public void storeAuthor(Author author)
        {

                sessionFactory.getCurrentSession().save(author);
        }
        public void storeBook(Book book){
                sessionFactory.getCurrentSession().save(book);
        }
        public void authorListUpdate(){
                authorList = sessionFactory.getCurrentSession().createCriteria(Author.class).list();
        }
        public void bookListUpdate(){
                bookList = sessionFactory.getCurrentSession().createCriteria(Book.class).list();
        }

        // list authors
        @Transactional
        @GetMapping("/authors") // list
        public String author_home(Model model) {
                model.addAttribute("authors", authorList);
                //System.out.println(" \r\n \r\n \r\n \r\n \r\n \r\n Authors\r\n \r\n\r\n");
                return "authors";
        }
        @Transactional
        @GetMapping("/add_author") // add author to list
        public String addAuthor(Model model) {
                Author author = new Author();
                model.addAttribute("author", author);
                return "/add_author";
        }
        @Transactional
        @PostMapping("/save_author") // adds the author, redirects to list
        public String saveAuthor(@ModelAttribute("author") Author author){
                //author.setId(authorList.size() + 1);
                storeAuthor(author);
                authorListUpdate();
                return "redirect:/authors";
        }


        /** ****************BOOK CONTROLLER********************
         *
         *
         *
         */

        // list books
        @Transactional
        @GetMapping("/books")
        public String book_home(Model model) {
                model.addAttribute("books", bookList);
                return "books";
        }
        @Transactional
        @GetMapping("/add_book")
        public String addBook(Model model){
                Book book = new Book();
                model.addAttribute("book", book);
                return "add_book";
        }
        @Transactional
        @PostMapping("/save_book")
        public String saveBook(@ModelAttribute("book") Book book){
                //bookList.add(book);
                //storeBook(book);
                //bookListUpdate();
                return "redirect:/books";
        }

--Book.java--

package my.package.model;


import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.*;





@Entity
@Table(name = "Book")
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long ISBN;
    private String title;
    private String releaseYear;
    private Author author;

    public Book(){

    }
    public Book(long ISBN, String title, String releaseYear, Author author){
        this.ISBN = ISBN;
        this.title = title;
        this.releaseYear = releaseYear;
        this.author = author;
    }

    public long getISBN() {
        return ISBN;
    }

    public void setISBN(long ISBN) {
        this.ISBN = ISBN;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getReleaseYear() {
        return releaseYear;
    }

    public void setReleaseYear(String releaseYear) {
        this.releaseYear = releaseYear;
    }

    public Author getAuthor() {
        return author;
    }

    public void setAuthor(Author author) {
        this.author = author;
    }
}

--Author.java--

package my.package.model;
import javax.persistence.*;


@Entity
@Table(name = "Author")
public class Author {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String firstName;
    private String lastName;
    private String nationality;

    public Author() {
    }
    public Author(long id, String firstName, String lastName, String nationality){
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
        this.nationality = nationality;
    }

    public long getId() {
        return id;
    }

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

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getNationality() {
        return nationality;
    }

    public void setNationality(String nationality) {
        this.nationality = nationality;
    }
}

我的

Answer 1

只需在 Book 类的作者字段中添加 @ManyToOne 即可。

Hibernate 会抛出异常，因为它无法将 Author 识别为映射数据库类型。事实上，它不是类型，而是表之间的关系。