Spring应用Bean扫描异常：无法找到MessageRepository Bean

启动应用时出现如下错误：

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of constructor in com.example.redacted.redacted.service.MessageServiceImpl required a bean of type 'com.example.redacted.redacted.repositories.MessageRepository' that could not be found.


Action:

Consider defining a bean of type 'com.example.redacted.redacted.repositories.MessageRepository' in your configuration.


Process finished with exit code 0

相关代码文件 #

主应用类 #

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class EmmiesprojectApplication extends SpringBootServletInitializer implements WebMvcConfigurer {

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

}

Controller类 #

@RestController
@RequiredArgsConstructor
public class MessageController {

    private final MessageService messageService;


    @LogEndoint
    @GetMapping("/message")
    public ResponseEntity<Message> getMessage(){
        return new  ResponseEntity<>(messageService.getMessage(), HttpStatus.OK);
    }



    @LogEndoint
    @GetMapping("/status")
    public ResponseEntity<String> getStatus(){
        return new ResponseEntity<>("Service is good to go",HttpStatus.OK);
    }


}

Service实现类 #

@Service
@RequiredArgsConstructor
public class MessageServiceImpl implements MessageService{
    
    private final MessageRepository messageRepository;

    @Override
    public Message getMessage() {
        long id = 1;
        String message = String.valueOf(messageRepository.findById(id));
        return new Message();
        //return message.orElse(null);
    }

    @Override
    public void setMessage(String message) {

    }
}

Repository接口 #

@Repository
public interface MessageRepository extends CrudRepository<Message, Long> {
}

Message实体类 #

@RequiredArgsConstructor
@AllArgsConstructor
@Builder
@Data
@Entity
public class Message {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    private String message;
}

application.properties配置 #

#Security -------------------------------------------------
security.ignored=/**
security.basic.enabled=false
management.security.enabled=false

#Database -------------------------------------------------
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.PostgreSQLDialect
spring.jpa.hibernate.ddl-auto=none
spring.jpa.hibernate.show-sql=true
spring.datasource.url=jdbc:postgresql://localhost:5432/projects
spring.datasource.username=postgres
spring.datasource.password=




#SQL -------------------------------------------------------
#create sql for getting and setting messages

#Config ----------------------------------------------------
spring.web.resources.add-mappings = false

build.gradle配置 #

plugins {
    id 'java'
    id 'org.springframework.boot' version '3.2.4'
    id 'io.spring.dependency-management' version '1.1.4'
}

group = 'com.example.redacted'
version = '0.0.1-SNAPSHOT'

java {
    sourceCompatibility = '17'
}

configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
}

repositories {
    mavenCentral()
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-batch'
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation 'org.springframework.boot:spring-boot-starter-data-jpa:3.2.4'
    implementation 'javax.persistence:javax.persistence-api:2.2'
    implementation 'jakarta.persistence:jakarta.persistence-api:3.0.0'
    implementation 'org.hibernate:hibernate-core:7.0.0.Alpha1'


    //swagger
    implementation 'io.springfox:springfox-swagger-ui:3.0.0'

    //spotless
    implementation 'com.diffplug.spotless:spotless-lib:2.45.0'
    implementation "com.diffplug.spotless:spotless-plugin-gradle:6.25.0"

    compileOnly 'org.projectlombok:lombok'
    developmentOnly 'org.springframework.boot:spring-boot-devtools'
    runtimeOnly 'com.mysql:mysql-connector-j'
    runtimeOnly 'org.postgresql:postgresql'
    annotationProcessor 'org.projectlombok:lombok'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    testImplementation 'org.springframework.batch:spring-batch-test'
}



tasks.named('test') {
    useJUnitPlatform()
}

已尝试的方法 #

• 使用@ComponentScan注解指定扫描路径
• 替换@SpringBootApplication为@Configuration+@EnableAutoConfiguration+@ComponentScan组合注解
• 确保主应用类位于根包，其他类在子包下

解决方案 #

1. 移除DataSourceAutoConfiguration排除配置 #

你在@SpringBootApplication中排除了DataSourceAutoConfiguration.class，但项目依赖JPA和PostgreSQL数据源，这个自动配置类是Spring Boot初始化数据源、JPA相关Bean的核心，排除它会导致Spring无法生成Repository代理Bean。

修改主应用类：

@SpringBootApplication
public class EmmiesprojectApplication extends SpringBootServletInitializer implements WebMvcConfigurer {

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

}

2. 清理冲突的JPA依赖 #

Spring Boot 3.x使用Jakarta EE规范（对应jakarta.persistence包），但你同时引入了旧Java EE规范的javax.persistence:javax.persistence-api:2.2，两者冲突会导致JPA注解无法被正确识别。另外手动引入的org.hibernate:hibernate-core:7.0.0.Alpha1是测试版，和spring-boot-starter-data-jpa自带的Hibernate版本不兼容，需要移除。

修改后的dependencies部分：

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-batch'
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation 'org.springframework.boot:spring-boot-starter-data-jpa'

    //swagger
    implementation 'io.springfox:springfox-swagger-ui:3.0.0'

    //spotless
    implementation 'com.diffplug.spotless:spotless-lib:2.45.0'
    implementation "com.diffplug.spotless:spotless-plugin-gradle:6.25.0"

    compileOnly 'org.projectlombok:lombok'
    developmentOnly 'org.springframework.boot:spring-boot-devtools'
    runtimeOnly 'org.postgresql:postgresql'
    annotationProcessor 'org.projectlombok:lombok'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    testImplementation 'org.springframework.batch:spring-batch-test'
}

3. 确认包扫描路径 #

主应用类EmmiesprojectApplication所在包com.example.redacted，MessageRepository所在包com.example.redacted.redacted.repositories属于其子包，Spring Boot默认会扫描主类所在包及子包，无需额外配置@ComponentScan。

4. 验证步骤 #

1. 清理构建缓存：执行./gradlew clean
2. 重新构建启动：执行./gradlew bootRun
3. 先访问/status确认服务启动，再测试/message接口验证Repository是否正常工作

内容的提问来源于stack exchange，提问作者mrsteel2935