在REST API中创建bean名称时出现不满意的DependencyException错误

Question

**2021-11-26 20:30:57.375 WARN 11700---[restartedMain]ConfigServlet WebServerApplicationContext:在上下文初始化期间遇到异常-取消刷新尝试：org.springframework.beans.factory.UnsatisfiedDependencyException：创建名为"bookRestController"的bean时出错：通过字段"bookService"表达的不满足依赖关系；嵌套异常为org.springframework.beans.factory.UnsatisfiedDependencyException：创建名为"bookServiceImpl"的bean时出错：通过字段"bookService"表示的不满足依赖项；嵌套异常为org.springframework.beans.factory.BeanCurrentlyInCreationException：创建名为"bookServiceImpl"的bean时出错：请求的bean当前正在创建中：是否存在无法解决的循环引用？2021-11-26 20:30:57.376信息11700---[restartedMain]j.LocalContainerEntityManagerFactoryBean：正在关闭持久性单元"default"的JPA EntityManagerFactory2021-11-26 20:30:57.382信息11700-[restartedMain]com.zaxxer.hikari.HikariDataSource:HikariPool-1-启动关闭。。。2021-11-26 20:30:57.393信息11700-[restartedMain]com.zaxxer.hikari.HikariDataSource:HikariPool-1-关闭完成。2021-11-26 20:30:57.396信息11700---[restartedMain]o.apache.catalina.core.StandardService:正在停止服务[Tomcat]2021-11-26 20:30:57.410信息11700---[restartedMain]条件评估报告LoggingListener:

启动ApplicationContext时出错。若要显示条件报告，请在启用"调试"的情况下重新运行应用程序。2021-11-26 20:30:57.437错误11700---[restartedMain]o.s.b.d.LoggingFailureAnalysisReporter：**

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应用程序无法启动

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描述：

应用程序上下文中某些bean的依赖关系形成一个循环：

bookRestController(字段专用BookAuthorManyToManyRelationship.service.BookService BookAuthormanyToManyBRelationship.Rest.bookRestController.BookService(┌─────┐|bookServiceImpl(字段专用BookAuthorManyToManyRelationship.service.BookService BookAuthormanyToManyGrelationship.serviceImpl.bookServiceImpl.BookService(└─────┘

行动：

不鼓励依赖循环引用，并且默认情况下禁止循环引用。更新应用程序以删除bean之间的依赖循环。作为最后的手段，可以通过将spring.min.allow-circular-references设置为true来自动打破循环。*

BasicProjectApplication.java

```package BookAuthorManyToManyRelationship;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;
@SpringBootApplication
public class BasicProjectApplication {
public static void main(String[] args) {
SpringApplication.run(BasicProjectApplication.class, args);
}
}```
**AuthorDAO.java**
```package BookAuthorManyToManyRelationship.dao;
import java.util.List;
import BookAuthorManyToManyRelationship.entity.Author;
import BookAuthorManyToManyRelationship.entity.Book;
public interface AuthorDAO {
public Author findById(int id);
public List<Book> findListOfBookWrittenByAuthor();
public void deleteById(int id);
public void save(Author author);
}```
**BookDAO.java**
```package BookAuthorManyToManyRelationship.dao;
import java.util.List;
import BookAuthorManyToManyRelationship.entity.Author;
import BookAuthorManyToManyRelationship.entity.Book;
public interface BookDAO {
public Book findById(int id);
public List<Author> findListOfAuthorWhoHasWrittenThisBook();
public void deleteById(int id);
public void save(Book book);
}```
**AuthorDAOImpl.java**
```package BookAuthorManyToManyRelationship.daoImpl;
import java.util.List;
import javax.persistence.EntityManager;
import org.hibernate.Session;
import org.hibernate.query.Query;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import BookAuthorManyToManyRelationship.dao.AuthorDAO;
import BookAuthorManyToManyRelationship.entity.Author;
import BookAuthorManyToManyRelationship.entity.Book;
@Repository
public class AuthorDAOImpl implements AuthorDAO {
@Autowired
private EntityManager entityManager;
@Override
public Author findById(int id) {
Session session = entityManager.unwrap(Session.class);
Author author = session.get(Author.class, id);

return author;
}
@Override
public List<Book> findListOfBookWrittenByAuthor() {

Session session = entityManager.unwrap(Session.class);
Query<Book> theQuery = session.createQuery("from Book",Book.class);

List<Book> book = theQuery.getResultList();
return book;
}
@Override
public void deleteById(int id) {

Session session = entityManager.unwrap(Session.class);

Query theQuery = session.createQuery("delete from Author where author_id=:theid");
theQuery.setParameter("theid", id);
theQuery.executeUpdate();
}
@Override
public void save(Author author) {
Session session = entityManager.unwrap(Session.class);
session.saveOrUpdate(author);
}
}```
**BookDAOImpl.java**
```package BookAuthorManyToManyRelationship.daoImpl;
import java.util.List;
import javax.persistence.EntityManager;
import org.hibernate.Session;
import org.hibernate.query.Query;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import BookAuthorManyToManyRelationship.dao.BookDAO;
import BookAuthorManyToManyRelationship.entity.Author;
import BookAuthorManyToManyRelationship.entity.Book;
@Repository
public class BookDAOImpl implements BookDAO {

@Autowired
private  EntityManager  entityManager;
@Override
public Book findById(int id) {

Session session = entityManager.unwrap(Session.class);
Book b = session.get(Book.class, id);
return b;
}
@Override
public List<Author> findListOfAuthorWhoHasWrittenThisBook() {

Session session = entityManager.unwrap(Session.class);
Query<Author> q = session.createQuery("from Author",Author.class);
List<Author> author = q.getResultList();
return author;
}
@Override
public void deleteById(int id) {

Session session = entityManager.unwrap(Session.class);
Query q = session.createQuery("delete from Book where book_id:=theid");
q.setParameter("theid", id);
q.executeUpdate();
}
@Override
public void save(Book book) {

Session session = entityManager.unwrap(Session.class);
session.saveOrUpdate(book);

}
}```
**Address.java**
```package BookAuthorManyToManyRelationship.entity;
import javax.persistence.Embeddable;
@Embeddable
public class Address {
String street;
String city;
String country;
public Address(String street, String city, String country) {
super();
this.street = street;
this.city = city;
this.country = country;
}
public Address() {
super();
// TODO Auto-generated constructor stub
}
public String getStreet() {
return street;
}
public void setStreet(String street) {
this.street = street;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}

}```
**Author.java**
```package BookAuthorManyToManyRelationship.entity;
import java.util.List;
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.ManyToMany;
import javax.persistence.Table;
@Entity
@Table(name="author")
public class Author {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
int id;
String authorName;
Address address;
@ManyToMany(cascade = CascadeType.ALL)
List<Book> book;
public Author() {
super();
// TODO Auto-generated constructor stub
}
public Author(int id, String authorName,Address address,List<Book> book) {
super();
this.id = id;
this.authorName = authorName;
this.address = address;
this.book = book;
}

public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getAuthorName() {
return authorName;
}
public void setAuthorName(String authorName) {
this.authorName = authorName;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public List<Book> getBook() {
return book;
}
public void setBook(List<Book> book) {
this.book = book;
}

}```
**Book.java**
```package BookAuthorManyToManyRelationship.entity;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
@Entity
@Table(name="book")
public class Book {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
int id;
String book_name;
String subject;
@ManyToMany(cascade = CascadeType.ALL)
List<Author> author;
public Book() {
super();
// TODO Auto-generated constructor stub
}
public Book(int id, String book_name, String subject, List<Author> author) {
super();
this.id = id;
this.book_name = book_name;
this.subject = subject;
this.author = author;
}

public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getBook_name() {
return book_name;
}
public void setBook_name(String book_name) {
this.book_name = book_name;
}
public String getSubject() {
return subject;
}
public void setSubject(String subject) {
this.subject = subject;
}
public List<Author> getAuthor() {
return author;
}
public void setAuthor(List<Author> author) {
this.author = author;
}


}```
**AuthorRestController**
```package BookAuthorManyToManyRelationship.Rest;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import BookAuthorManyToManyRelationship.entity.Author;
import BookAuthorManyToManyRelationship.entity.Book;
import BookAuthorManyToManyRelationship.service.AuthorService;
@RestController
@RequestMapping("/welcome")
public class AuthorRestController {

@Autowired
private AuthorService authorService;

@GetMapping("/author/{id}")
public Author getAuthorById(@PathVariable int id )
{
return authorService.findById(id);
}


@GetMapping("/book")
public List<Book> getBook()
{
return authorService.findListOfBookWrittenByAuthor();
}

@PostMapping("/saveAuthor")
public void setAuthor(@RequestBody Author author)
{
authorService.save(author);
}


}```
**BookRestController.java**
```package BookAuthorManyToManyRelationship.Rest;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import BookAuthorManyToManyRelationship.entity.Author;
import BookAuthorManyToManyRelationship.entity.Book;
import BookAuthorManyToManyRelationship.service.BookService;
@RestController
@RequestMapping("/abc")
public class BookRestController {

@Autowired
private BookService bookService;


@GetMapping("/book/{id}")
public Book getBookById(@PathVariable int id )
{
return bookService.findById(id);
}

@GetMapping("/author")
public List<Author> getAuthor()
{
return bookService.findListOfAuthorWhoHasWrittenThisBook();
}


@PostMapping("/saveBook")
public void setBook(@RequestBody Book book)
{       
bookService.save(book);
}

}```
**AuthorService.java**
```package BookAuthorManyToManyRelationship.service;
import java.util.List;

import BookAuthorManyToManyRelationship.entity.Author;
import BookAuthorManyToManyRelationship.entity.Book;
public interface AuthorService {
public Author findById(int id);
public List<Book> findListOfBookWrittenByAuthor();
public void deleteById(int id);
public void save(Author author);
}```
**BookService.java**
```package BookAuthorManyToManyRelationship.service;
import java.util.List;
import BookAuthorManyToManyRelationship.entity.Author;
import BookAuthorManyToManyRelationship.entity.Book;
public interface BookService {
public Book findById(int id);
public List<Author> findListOfAuthorWhoHasWrittenThisBook();
public void deleteById(int id);
public void save(Book book);

}```
**AuthorServiceImpl.java**
```package BookAuthorManyToManyRelationship.serviceImpl;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import BookAuthorManyToManyRelationship.dao.AuthorDAO;
import BookAuthorManyToManyRelationship.entity.Author;
import BookAuthorManyToManyRelationship.entity.Book;
import BookAuthorManyToManyRelationship.service.AuthorService;
@Service
public class AuthorServiceImpl implements AuthorService {
@Autowired
private AuthorDAO authorDAO;


@Override
@Transactional
public Author findById(int id) {
return authorDAO.findById(id);
}
@Override
@Transactional
public List<Book> findListOfBookWrittenByAuthor() {
return authorDAO.findListOfBookWrittenByAuthor();
}
@Override
@Transactional
public void deleteById(int id) {
authorDAO.deleteById(id);
}
@Override
@Transactional
public void save(Author author) {
authorDAO.save(author);
}
}```
**BookServiceImpl.java**
```package BookAuthorManyToManyRelationship.serviceImpl;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import BookAuthorManyToManyRelationship.entity.Author;
import BookAuthorManyToManyRelationship.entity.Book;
import BookAuthorManyToManyRelationship.service.BookService;
@Service
public class BookServiceImpl implements BookService {

@Autowired
private BookService bookService;

@Override
@Transactional
public Book findById(int id) {
return bookService.findById(id);
}
@Override
@Transactional
public List<Author> findListOfAuthorWhoHasWrittenThisBook() {
return bookService.findListOfAuthorWhoHasWrittenThisBook();
}
@Override
@Transactional
public void deleteById(int id) {
bookService.deleteById(id);
}
@Override
@Transactional
public void save(Book book) {
bookService.save(book);
}

}
```

Answer 1

以下是问题的原因

@Service
public class BookServiceImpl implements BookService {

@Autowired
private BookService bookService

我不明白为什么你在自己的实现中引用了BookService，我猜你想在这里添加BookDAO。