Spring Boot费用追踪项目启动报错：找不到CategoryRepository类型Bean

问题概述 #

搭建费用追踪（expense tracker）项目基础结构后，启动时出现Bean找不到的错误，无法正常启动应用。

错误信息 #

APPLICATION FAILED TO START #

描述：
com.app.expensetracker.service.CategoryServiceImpl中的categoryRepository字段需要类型为'com.app.expensetracker.dao.CategoryRepository'的Bean，但未找到。
注入点带有以下注解：

• @org.springframework.beans.factory.annotation.Autowired(required=true)

建议操作：
考虑在配置中定义类型为'com.app.expensetracker.dao.CategoryRepository'的Bean。

相关代码片段 #

CategoryRepository #

package com.app.expensetracker.dao;

import com.app.expensetracker.entity.Category;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface CategoryRepository extends JpaRepository<Category, String> {

}

Category实体类 #

package com.app.expensetracker.entity;

import jakarta.persistence.*;
import lombok.*;
import java.util.List;

@Entity
@Table(name = "category")
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
@Builder
@ToString

public class Category {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name="cat_id",nullable = false)
    private String cat_id;

    @Column(name="categoryName")
    private String categoryName;

    @Column(name="users")
    private List<String> users;

//    @ManyToOne(cascade = CascadeType.ALL,fetch = FetchType.LAZY)
//    @JoinColumn(name = "user_id")
//    private  User user;

}

CategoryService接口 #

package com.app.expensetracker.service;

import com.app.expensetracker.dto.CategoryCreateRequest;
import com.app.expensetracker.entity.Category;
import org.springframework.http.ResponseEntity;
import java.util.Optional;

public interface CategoryService {

    Category createCategory(CategoryCreateRequest categoryCreateRequest);
    ResponseEntity<Optional<Category>> getCategoryById(String category_id);
    Category updateCategory(String categoryId, CategoryCreateRequest categoryCreateRequest);
    ResponseEntity<Optional<Category>> deleteCategoryById(String category_id);
}

CategoryServiceImpl实现类 #

package com.app.expensetracker.service;
import com.app.expensetracker.dao.CategoryRepository;
import com.app.expensetracker.dto.CategoryCreateRequest;
import com.app.expensetracker.entity.Category;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.Optional;

@Service
public class CategoryServiceImpl implements CategoryService{
@Autowired
private CategoryRepository categoryRepository;

    @Override
    @Transactional
    public Category createCategory(CategoryCreateRequest categoryCreateRequest){
        Category category = categoryCreateRequest.to();
        return categoryRepository.save(category);
    }
    
    
    @Override
    @Transactional
    public ResponseEntity<Optional<Category>> getCategoryById(String category_id){
    
        Optional<Category> category =  categoryRepository.findById(category_id);
        if(category == null){
            return ResponseEntity.notFound().build();
        }
        else{
            return ResponseEntity.ok(category);
        }
    
    }
    
    @Override
    @Transactional
    public Category updateCategory(String categoryId, CategoryCreateRequest categoryCreateRequest){
        Category category = categoryCreateRequest.to();
        return categoryRepository.save(category);
    }
    
    @Override
    @Transactional
    public ResponseEntity<Optional<Category>> deleteCategoryById(String category_id){
        Optional<Category> category =  categoryRepository.findById(category_id);
        if(category == null){
            return ResponseEntity.notFound().build();
        }
        else{
            categoryRepository.deleteById(category_id);
            return ResponseEntity.ok(category);
        }
    }

}

ExpenseTrackerApplication启动类 #

package com.app.expensetracker;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@SpringBootApplication //(exclude = {DataSourceAutoConfiguration.class })
//@ComponentScan(basePackages = "com.app.*")
//@EntityScan("com.app.*")
@EnableJpaRepositories(basePackages = "com.app.expensetracker.repository")

public class ExpenseTrackerApplication {

    public static void main(String[] args) {

        SpringApplication.run(ExpenseTrackerApplication.class, args);
    }

}

解决方案 #

问题根源在于启动类中@EnableJpaRepositories注解的包路径配置错误：你的CategoryRepository实际位于com.app.expensetracker.dao包下，但注解中指定的扫描路径是com.app.expensetracker.repository，导致Spring无法找到该Repository接口并创建对应的Bean。

有两种解决方式：

方式一：修正@EnableJpaRepositories的扫描路径 #

修改启动类中的注解，将basePackages改为Repository所在的包：

package com.app.expensetracker;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@SpringBootApplication
@EnableJpaRepositories(basePackages = "com.app.expensetracker.dao")
public class ExpenseTrackerApplication {

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

}

如果存在多个Repository包，可通过数组形式指定多个路径：
@EnableJpaRepositories(basePackages = {"com.app.expensetracker.dao", "com.app.expensetracker.other.repository"})

方式二：移除@EnableJpaRepositories注解 #

@SpringBootApplication注解默认会扫描主类所在包（com.app.expensetracker）及其所有子包下的Spring组件，包括Repository接口。由于你的CategoryRepository已经在com.app.expensetracker.dao（主类包的子包）下，直接删除@EnableJpaRepositories注解，Spring会自动识别并创建Repository Bean：

package com.app.expensetracker;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class ExpenseTrackerApplication {

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

}

内容的提问来源于stack exchange，提问作者Giribala