映射@Entity时出现UnsatisfiedDependencyException beancreationerror

Question

I am trying to implement a Hibernate spring mvc project using MySql, and having issues when Mapping my Book class with @Entity. The MySql server works fine with Author.java, however the moment I map @Entity to by Book class I get the HTTP Status 500 code.

Think the issue lies in hibernates way of accepting the tables and that no table named Book is being initialized during my sessionFactory session. The hibernate config works fine with only my Author.java class.

Maybe the issue lies in that the book class has a reference to my author?

public class Book {

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

Error line: 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.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)]

--Error code--

   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;
    }
}

my

Answer 1

Just add @ManyToOne on author field in Book class.

Hibernate throws because it doesn't recognize Author as a mapped database type. In fact, it's not a type, but a relationship between tables.

Answer 2

您需要定义Book和Author之间的关系，例如OnetoOne等。错误显示Author没有与任何数据库列映射，由于Author是对象类型（多个字段的组合），我们无法直接将Author与任何数据库列映射。