无法向Spring data starter项目添加第二个实体

Question

但是，当我添加另一个实体Person和一个PersonRepository并尝试持久化该实体时，会出现如下所示的错误。这就像在application.java中存在某种内部类$1一样，Spring数据试图将其映射为一个实体。

java.lang.IllegalArgumentException：未知实体：Hello.Application$1

package hello;

import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;

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

@Entity
@ToString
@NoArgsConstructor
@Data
public class Person {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private int age;
}

package hello;

import org.springframework.data.repository.CrudRepository;

public interface PersonRepository extends CrudRepository<Person, Long> {
}

package hello;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
@Slf4j
public class Application {

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

    /*
    @Bean
    public CommandLineRunner demo(CustomerRepository repository) {
        return (args) -> {
            repository.save(new Customer("Jack", "Bauer"));
            repository.save(new Customer("Chole", "O'Brian"));
            repository.save(new Customer("Kim", "Bauer"));
            repository.save(new Customer("David", "Palmer"));
            repository.save(new Customer("Michelle", "Dessler"));

            // fetch all customers
            log.info("Customers found with findAll():");
            log.info("-------------------------------");
            repository.findAll().forEach(c -> log.info(c.toString()));
        };
    }
    */

    @Bean
    public CommandLineRunner demo(PersonRepository repository) {
        return (args) -> {
            repository.save(new Person(){{
                setAge(20);
            }});

            // fetch all customers
            log.info("Customers found with findAll():");
            log.info("-------------------------------");
            repository.findAll().forEach(c -> log.info(c.toString()));
        };
    }
}

Answer 1

错误消息清楚地表明您有一个未映射的类。你正确地扣除了

这就像在application.java中，有某种内部类$1，Spring data试图将其映射为一个实体。

所讨论的内部类在代码中定义为Person的子类

repository.save(new Person(){{
    setAge(20);
}});

Person p = new Person();
p.setAge(20);
repository.save(p)