Spring Boot启动报错：UserService依赖的UserRepository Bean未找到

我和团队在运行Spring Boot应用时接连踩坑，刚修复一个错误又冒出新问题，查了很多资料都没解决。

启动错误信息 #

Parameter 0 of constructor in com.earworm.backendearworm.UserService required a bean of type com.earworm.backendearworm.UserRepository that could not be found

我已经尝试过添加不同依赖，以下是相关代码：

UserService.java #

package com.earworm.backendearworm;

import java.time.LocalDateTime;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.UUID;

import com.earworm.registration.token.ConfirmationToken;
import com.earworm.registration.token.ConfirmationTokenService;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@Service
public class UserService implements UserDetailsService {

    private final UserRepository userRepository;
    private final BCryptPasswordEncoder bCryptPasswordEncoder;
    private final ConfirmationTokenService confirmationTokenService;

    public UserService(UserRepository userRepository, BCryptPasswordEncoder bCryptPasswordEncoder,
            ConfirmationTokenService confirmationTokenService) {
        this.userRepository = userRepository;
        this.bCryptPasswordEncoder = bCryptPasswordEncoder;
        this.confirmationTokenService = confirmationTokenService;
    }

    public List<User> getUsers() {
        return userRepository.findAll();
    }

    public String addNewUser(User user) {
        Optional<User> userByEmail = userRepository.findUserByEmail(user.getEmail());
        if (userByEmail.isPresent()) {
            throw new IllegalStateException("Email taken");
        }
        String encodedPassword = bCryptPasswordEncoder.encode(user.getPassword());
        user.setPassword(encodedPassword);
        userRepository.save(user);

        String token = UUID.randomUUID().toString();
        ConfirmationToken confirmationToken = new ConfirmationToken(token, LocalDateTime.now(),
                LocalDateTime.now().plusMinutes(15), user);

        confirmationTokenService.saveConfirmationToken(confirmationToken);

        return token;
    }
    /*
     * Fix exists by ID by actually passing id and changing repository from string
     * to long
     */
    public void deleteUser(Long id) {
        boolean userExists = userRepository.existsById(id);
        if (!userExists) {
            throw new IllegalStateException("User with id " + id + " does not exist");
        }
        userRepository.deleteById(id);

    }

    // Name and email are optional
    @Transactional
    public void updateUser(Long id, String username, int zipCode, String bio) {
        User user = userRepository.findById(id)
                .orElseThrow(() -> new IllegalStateException("User with id " + id + " does not exist"));

        if (username != null && username.length() > 0 && !Objects.equals(user.getUsername(), username)) {
            user.setUsername(username);
        }
        // -------Change email if wanted-------
        // if (email != null && email.length() > 0 && !Objects.equals(user.getEmail(),
        // email)) {
        // Optional<User> userOptional = userRepository.findUserByEmail(email);
        // if (userOptional.isPresent()) {
        // throw new IllegalStateException("Email taken");
        // }
        // user.setEmail(email);
        // }
        // Fix to lang and
        // long?>----------------------------------------------------------------------------------
        // user.setZipCode(zipCode);
        user.setBio(bio);

    }
/* 
    @Override
    public UserDetails loadUserByUsername(String email) throws UsernameNotFoundException {
        return userRepository.findUserByEmail(email)
                .orElseThrow(() -> new UsernameNotFoundException("user with email " + email + " not found"));
    }

    public int enableUser(String email) {
        return userRepository.enableUser(email);
    }
*/

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        // TODO Auto-generated method stub
        return null;
    }
}

UserRepository.java #

package com.earworm.backendearworm;

import java.util.List;
import java.util.Optional;

import org.springframework.context.annotation.Bean;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

public interface UserRepository extends JpaRepository<User, Long> {

    @Query("SELECT s FROM User s WHERE s.email = ?1")
    Optional<User> findUserByEmail(String email);

    // List<User> findAllByZipcode(int zipCode);

    // @Query("SELECT s FROM User s WHERE s.username = ?1")
    Optional<User> existsByUsername(String username);

    @Transactional
    @Modifying
    @Query("UPDATE user a " + "Set a.enabled = TRUE WHERE a.email = ?1")
    int enableUser(String email);

}

解决办法 #

针对这个报错，按以下步骤排查：

1. 给UserRepository添加@Repository注解：当前UserRepository接口只是导入了@Repository但未实际标注，Spring无法将其识别为可注入的Bean。修改后代码如下：

   @Repository
   public interface UserRepository extends JpaRepository<User, Long> {
       // 原有方法保持不变
   }
   

2. 检查Spring Boot主类的包扫描范围：确保主类所在的包是com.earworm或更上层（比如com），这样Spring会自动扫描子包com.earworm.backendearworm下的组件。如果主类在更深的子包，需要在主类上添加@ComponentScan(basePackages = "com.earworm")指定扫描范围。
3. 确认JPA依赖已正确引入：检查项目的构建文件（pom.xml或build.gradle），确保包含spring-boot-starter-data-jpa依赖：

   <!-- Maven示例 -->
   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-data-jpa</artifactId>
   </dependency>
   

4. 检查User实体类配置：确保User类添加了@Entity注解，并且主键字段标注了@Id（及@GeneratedValue），否则JPA无法为Repository生成代理实现类。

内容的提问来源于stack exchange，提问作者Rodolfo