Spring 启动时为 JpaRepository 创建 bean 时出错

Question

i bumped into a problem with my school project i was attempting to set up h2 database for. Everything ran fine i guess untill i created Repository interface for my database, which looks simply like this

package com.protonmail.jan.backend.repository;

import org.springframework.data.jpa.repository.JpaRepository;

public interface RecordRepository extends JpaRepository {
}

When i run the application without the repository code, the app at least starts, i'm pretty new to spring-boot, so i have no idea what's going on here, but i guess it's some dependencies or something needet to create beans missing on my pom.xml file? Please help, here is some of the error log i got:

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'requestMappingHandlerAdapter' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Unsatisfied dependency expressed through method 'requestMappingHandlerAdapter' parameter 1; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mvcConversionService' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.format.support.FormattingConversionService]: Factory method 'mvcConversionService' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'recordRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class java.lang.Object
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mvcConversionService' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.format.support.FormattingConversionService]: Factory method 'mvcConversionService' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'recordRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class java.lang.Object
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.format.support.FormattingConversionService]: Factory method 'mvcConversionService' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'recordRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class java.lang.Object
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'recordRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class java.lang.Object
Caused by: java.lang.IllegalArgumentException: Not a managed type: class java.lang.Object

this is my Record

package com.protonmail.jan.backend.entity;

import javax.persistence.*;
import javax.validation.constraints.NotEmpty;
import javax.validation.constraints.NotNull;
import java.util.Collection;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

@Entity
public class Record extends AbstractEntity {
    @NotNull
    @NotEmpty
    private Date date;

    @NotNull
    @NotEmpty
    private static Map<Integer, Room> rooms;
    static {
        rooms = new HashMap<Integer, Room>(){
            {
                put(1, new Room());
                put(2, new Room());
                put(3, new Room());
            }
        };
    }

    public Collection<Room> getAllRooms(){
        return this.rooms.values();
    }
}

this is Room, which is contained in Record

package com.protonmail.jan.backend.entity;

import javax.persistence.*;
import javax.validation.constraints.NotEmpty;
import javax.validation.constraints.NotNull;
import java.util.Map;

@Entity
public class Room extends AbstractEntity{
    private String name = "pokoj";
    private Boolean lit = false;
    private long temp = 0;

    public Room() {
    }
    public Boolean getLit() {
        return lit;
    }
    public void setLit(Boolean lit) {
        this.lit = lit;
    }
    public long getTemp() {
        return temp;
    }
    public void setTemp(long temp) {
        this.temp = temp;
    }
}

this is AbstractEntity class

package com.protonmail.jan.backend.entity;

import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.MappedSuperclass;

@MappedSuperclass
public abstract class AbstractEntity {
    @Id
    @GeneratedValue(strategy= GenerationType.SEQUENCE)
    private Long id;

    public Long getId() {
        return id;
    }

    public boolean isPersisted() {
        return id != null;
    }

    @Override
    public int hashCode() {
        if (getId() != null) {
            return getId().hashCode();
        }
        return super.hashCode();
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        AbstractEntity other = (AbstractEntity) obj;
        if (getId() == null || other.getId() == null) {
            return false;
        }
        return getId().equals(other.getId());
    }
}

i also have used

public interface RecordRepository extends JpaRepository<Repository, Long> {}

Answer 1

Please specify the managed object and id types in interface declaration:

public interface RecordRepository extends JpaRepository<PersitentClass, ClassId> {
}

Where: PersitentClass - the type of your entity model ClassId - the type of 'id' field

For the class details, please refer to JpaRepository doc .

Answer 2

@EnableJpaRepositories annotation on the configuration class

https://docs.spring.io/spring-data/data-jpa/docs/current/api/org/springframework/data/jpa/repository/config/EnableJpaRepositories.html

also so @Repository

Answer 3

I was stuck not being able to help spring create a bean for the custom interface that extended JpaRepository. Tried everything, finally the answer was that Springboot expects packages to be named a certain way so that all components can be autowired.

1. Follow any of the common examples for Spring boot JPA CRUD, like 1

2. Usually the package part of the code is clipped. There lies the trick. Spring boot expects the Application class, that is the one labelled @SpringbootApplication to be in package com.base.app, while the repository interface to be in com.base.app.repo. If you instead have com.base.repo, it cannot locate and create the bean!!

Answer 4

You can solve this by adding the following to the main class where spring boot starts running:

@Configuration
@ComponentScan
@EnableAutoConfiguration
@EntityScan("com.mine.alien") // path of the entity model
@EnableJpaRepositories("com.mine.demo.control") // path of jpa repository 

@SpringBootApplication
public class SpringJpah2Application {

    public static void main(String[] args) {
        SpringApplication.run(SpringJpah2Application.class, args);
    }
}