如何解决Kotlin Spring Boot中JPA实体非托管类型错误？

运行Kotlin编写的Spring Boot数据库微服务时，出现以下错误：

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'anagraficaServiceImpl': Unsatisfied dependency expressed through field 'repository': Error creating bean with name 'anagraficaRepository' defined in com.example.pecoDb.JPA.AnagraficaRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration: Not a managed type: class com.pecoDb.anagraficaDAO.AnagraficaJpa

相关代码片段 #

AnagraficaJpa 实体类 #

package com.pecoDb.anagraficaDAO

import jakarta.persistence.Column
import jakarta.persistence.Entity
import jakarta.persistence.GeneratedValue
import jakarta.persistence.Id
import jakarta.persistence.Table

@Entity
@Table
data class AnagraficaJpa(
    @Column
    val nome: String ,
    @Column
    val cognome: String ,
    @Column
    val dataNascita: String ,
    @Column
    val comune: String ,
    @Column
    val nazionalita: String ,
    @Column
    val provincia: String ,
    @Column
    val indirizzo: String,
    @Id
    @GeneratedValue
    val idPecoAnagrafica: Long?=null,
)

AnagraficaRepository 仓库接口 #

package com.example.pecoDb.JPA

import com.pecoDb.anagraficaDAO.AnagraficaJpa
import org.springframework.data.repository.CrudRepository

interface AnagraficaRepository:CrudRepository<AnagraficaJpa, Long> {
    fun findByname(name: String): AnagraficaJpa
}

pom.xml 核心配置 #

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.2</version>
        <relativePath/>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>PEcoDb</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <properties>
        <h2.version>1.4.196</h2.version>
        <hibernate-core.version>5.6.9.Final</hibernate-core.version>
        <hibernate-testing.version>5.6.9.Final</hibernate-testing.version>
        <java.version>17</java.version>
        <kotlin.version>1.9.22</kotlin.version>
        <mysql-connector-j.version>8.3.0</mysql-connector-j.version>
        <spring-cloud.version>2023.0.0</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>com.fasterxml.jackson.module</groupId>
            <artifactId>jackson-module-kotlin</artifactId>
        </dependency>
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <version>${mysql-connector-j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <configuration>
                    <args>
                        <arg>-Xjsr305=strict</arg>
                    </args>
                    <compilerPlugins>
                        <plugin>spring</plugin>
                        <plugin>jpa</plugin>
                    </compilerPlugins>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-allopen</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-noarg</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                </dependencies>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

application.properties 配置 #

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL8Dialect

错误核心是Spring Data JPA未扫描到实体类，导致无法识别为受管理的JPA类型，按以下步骤修复：

1. 明确指定实体与仓库的扫描范围 #

Spring Boot主类默认只扫描自身所在包及其子包，而你的实体类com.pecoDb.anagraficaDAO和仓库com.example.pecoDb.JPA分属不同根包，需在启动类上添加注解指定扫描路径：

import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication
import org.springframework.data.jpa.repository.config.EnableJpaRepositories
import jakarta.persistence.EntityScan

@SpringBootApplication
@EnableJpaRepositories(basePackages = ["com.example.pecoDb.JPA"])
@EntityScan(basePackages = ["com.pecoDb.anagraficaDAO"])
class PEcoDbApplication

fun main(args: Array<String>) {
    runApplication<PEcoDbApplication>(*args)
}

2. 修复Hibernate版本冲突 #

Spring Boot 3.2.2默认依赖Hibernate 6.x，但你手动指定了Hibernate 5.6.9（基于javax，与Spring Boot 3.x的Jakarta规范不兼容），删除pom.xml中以下配置，让Spring Boot自动管理版本：

<hibernate-core.version>5.6.9.Final</hibernate-core.version>
<hibernate-testing.version>5.6.9.Final</hibernate-testing.version>

3. 修正仓库方法命名规则 #

Spring Data JPA方法命名需与实体属性名匹配，你写的findByname对应实体的nome属性，应改为：

interface AnagraficaRepository:CrudRepository<AnagraficaJpa, Long> {
    fun findByNome(nome: String): AnagraficaJpa
}

4. 优化实体类注解（可选） #

为适配MySQL自增主键，建议给@GeneratedValue指定策略：

@Id
@GeneratedValue(strategy = jakarta.persistence.GenerationType.IDENTITY)
val idPecoAnagrafica: Long?=null,

内容的提问来源于stack exchange，提问作者Daniele Cosentino