Springboot：需要一个找不到的“javax.persistence.EntityManagerFactory”类型的bean

Posted 2023-02-26

【中文标题】Springboot：需要一个找不到的“javax.persistence.EntityManagerFactory”类型的bean

【英文标题】：Springboot: Required a bean of type 'javax.persistence.EntityManagerFactory' that could not be found

【发布时间】：2018-12-20 12:55:54

【问题描述】：

我正在开发一个 Spring Boot 应用程序，在启动服务器时遇到了这个错误。我不确定我是否错误地定义了任何注释或缺少任何依赖项。任何帮助将不胜感激。

主类：

@SpringBootApplication
@Configuration
@ComponentScan
@EnableAutoConfiguration

public class DemoApplication 

    public static void main(String[] args) 
        System.out.println("Hello world");
        SpringApplication.run(DemoApplication.class, args);
    

用户服务类：

@Service
public class UserService implements IUserService 

    @Autowired
    private UserDAO userDAO;

    @Override
    public List<UserDTO> getAllUsers() 

        List<User> entities = userDAO.getUsers();
        List<UserDTO> users = new ArrayList<UserDTO>();//Will never use directly User Object, will be using Tranferable objects

        Iterator<User> iterator = entities.iterator();

        while(iterator.hasNext()) 
            User user = iterator.next();
            users.add(ApiDTOBuilder.userToUserDTO(user));//We are building UserDTO object.
        
        return users;
    

    @Override
    public UserDTO getUserByUsername(String username) 
        User user = userDAO.getUser(username);
        return ApiDTOBuilder.userToUserDTO(user);
    

    @Override
    public void createUser(UserDTO user) 
        userDAO.createUser(ApiDTOBuilder.userDTOToUser(user));
    

    @Override
    public void updateUser(UserDTO user) 
        userDAO.updateUser(ApiDTOBuilder.userDTOToUser(user));

    

    @Override
    public void deleteUser(String username) 
        userDAO.deleteUser(username);
    

UserDAO 类：

@Repository 公共类 UserDAO 实现 IUserDAO

        @PersistenceContext
        EntityManager em;//JPA EntityManager is used to access a database in a particular application. It is used to manage persistent entity instances, to find entities by their primary key identity(As here is Username), and to query over all entities.

        @Override
        @Transactional
        public User getUser(String username) 
            return em.find(User.class, username); //Here entitymanager can find the username as it has the capability to find an entity by unique identifies
        


        @Override
        @Transactional
        public List<User> getUsers() 
            List<User> resultList = em.createQuery("FROM user_tbl", User.class).getResultList();
            return resultList;
        

        @Override
        @Transactional
        public void createUser(User user) 
            em.persist(user);//Make an instance managed and persistent.
        

        @Override
        @Transactional
        public void updateUser(User user) 
            em.merge(user);//Merge the state of the given entity into the current persistence context.
        

        @Override
        @Transactional
        public void deleteUser(String username) 
            User user = this.getUser(username);
            em.remove(user);//Remove the entity instance.
        

Build.gradle：

buildscript 
    ext 
        springBootVersion = '2.0.0.RELEASE'
    
    repositories 
        mavenCentral()
    
    dependencies 
        classpath("org.springframework.boot:spring-boot-gradle-plugin:$springBootVersion")
    


apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'

group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8

repositories 
    mavenCentral()



dependencies 
    compile('org.springframework.boot:spring-boot-starter-data-jpa')
    compile('org.springframework.boot:spring-boot-starter-web')
    compile('org.springframework.boot:spring-boot-starter-security')
    compile('org.hibernate.javax.persistence:hibernate-jpa-2.1-api:1.0.0.Final')
    compile('javax.xml.bind:jaxb-api:2.2.11')
    compile('org.springframework.boot:spring-boot-starter-test:2.0.2.RELEASE')
    compile('com.sun.xml.bind:jaxb-core:2.2.11')
    compile('com.sun.xml.bind:jaxb-impl:2.2.11')
    runtime('org.springframework.boot:spring-boot-devtools')
    runtime('mysql:mysql-connector-java')
    testCompile('org.springframework.boot:spring-boot-starter-test')

错误信息：

***************************
APPLICATION FAILED TO START
***************************
Description:

Field userDAO in com.example.demo.service.UserService required a bean of type 'javax.persistence.EntityManagerFactory' that could not be found.
Action:

Consider defining a bean of type 'javax.persistence.EntityManagerFactory' in your configuration.

我看到了所有相关的答案，并尝试实施这些建议，例如添加依赖项、在主类中添加符号等。但它显示了同样的错误。请有人帮助我。先感谢您。

P.S：我的应用程序的 Github 链接：https://github.com/heliOpenxCell/demo

【问题讨论】：

为什么application.properties中有这行：spring.autoconfigure.exclude=org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration

这就是问题所在。另外，开始使用 Spring 数据。这比使用类似 sql 的查询创建自定义 DAO 要容易得多。使用 Spring Boot 时，您永远不必在任何地方注入实体管理器。

另外在主类和WebConfiguration类中有很多不必要的配置。另外还有多余的 gradle 依赖。你为什么不保留 Spring Initializer 正在创建的东西呢？

在 Spring Data 中，您永远不必显式配置 EntityManager。如果您这样做，则说明您错误地使用了整个库。也使用存储库模式。 DAO 模式已经过时了，而且已经远远超过了关系数据库的按日期销售。

如果我想创建持久上下文怎么办？如何创建并传入 Tasklet？

【参考方案1】：

我遇到了同样的问题，只需将其添加到您的 maven 或 gradle，它对我有用！

马文：

<dependency>
  <groupId>org.apache.tomcat</groupId>
  <artifactId>tomcat-jdbc</artifactId>
  <version>9.0.10</version>
</dependency>

分级：

compile group: 'org.apache.tomcat', name: 'tomcat-jdbc', version: '9.0.10'