SpringBoot 整合JPA 出现 Error creating bean with name 'userDAO':Not a managed type的问题

日志信息：

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'loginController': Unsatisfied dependency expressed through field 'loginService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: 
Error creating bean with name 'loginService': Unsatisfied dependency expressed through field 'userRepository'; nested exception is org.springframework.beans.factory.BeanCreationException:
 Error creating bean with name 'userRepository': 
 Invocation of init method failed; nested exception is java.lang.IllegalArgumentException:
  Not a managed type: class com.it.cloud.common.domain.Users

bean注入失败，简单来说就是在加载SpringBoot 的启动类时JPA的实体类找不到，没有被扫描到。导致这样的情况有以下几种可能。

1、实体类上缺少@Entity注解—在实体类上加上注解即可

 
@Entity
public class User {
    // 主键
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

2、 没有按照SpringBoot的约定,默认扫描(SpringApplication.java 启动类相对的兄弟包及其子包)

2.1 将SpringBootApplication.java(启动类)放置到更高层级的包,使得项目结构符合SpringBoot约定扫描的规则

2.2 在启动类中添加要扫描的包

注解	作用
@ComponentScan(basePackages = “com.boot.demo.xxx..”)	用于扫描@Controller @Service
@EnableJpaRepositories(basePackages = “com.boot.demo.xxx.*.dao”)	用于扫描Dao @Repository
@EntityScan(“com.boot.demo.xxx..”)	用于扫描JPA实体类 @Entity

@SpringBootApplication
@EntityScan("com.heima.domain")
public class SpringbootJpaApplication {
 
	public static void main(String[] args) {
		SpringApplication.run(SpringbootJpaApplication.class, args);
	}
}