没有匹配的类型的bean ...找到依赖....期望至少1个bean有资格作为autowire候选者

Question

这已经多次回答，但是我已经设置了所有注释，并且它似乎正确连线。

UserService接口：

public interface UserService {

    User findUserById(Long id);
    User findUserByName(String name);
    List<User> findAllUsers();
    void saveUser(User user);
    void updateUser(User user);
    void deleteUserById(long id);
    void deleteAllUsers();
    public boolean isUserExist(User user);
}

UserServiceImpl

@Service
@Transactional
public class UserServiceImpl implements UserService {

    private static final AtomicLong counter = new AtomicLong();

    private static List<User> users;

    static {
        users = populateDummyUsers();
    }

    @Override
    public User findUserById(Long id) {

        for (User user : users) {
            if (user.getId() == id) {
                return user;
            }
        }

        return null;
    }

    @Override
    public User findUserByName(String name) {
        for (User user : users) {
            if (user.getUsername().equalsIgnoreCase(name)) {
                return user;
            }
        }
        return null;
    }

失败的测试用例：

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = SpringCrudApplication.class)
@ComponentScan("com.service")
public class ServiceTest {


    private UserService userService;

    @Autowired
    public void setUserService(UserService userService) {
        this.userService = userService;
    }

    @Test
    public void findUserByIdTest() throws Exception {

        long id = (long) 0;
        User userTest = new User(id,"Mike","644 Main St", "apple@gmail.com");

        User user = userService.findUserById(id);

        assert user.getAddress() != null;
        assert user.getEmail() != null;
        assert user.getUsername() != null;

    }

我试过在com.service和com.serviceImpl上的测试类中使用componentScan而没有运气。

完整错误：

org.springframework.beans.factory.UnsatisfiedDependencyException:   
Error creating bean with name 'com.service.test.ServiceTest': 
Unsatisfied dependency expressed through method 'setUserService' 
parameter 0: No qualifying bean of type [com.service.UserService] 
found for dependency [com.service.UserService]: expected at least 1 
bean which qualifies as autowire candidate for this dependency. 
Dependency annotations: {}; nested exception is 
org.springframework.beans.factory.NoSuchBeanDefinitionException: No 
qualifying bean of type [com.service.UserService] found for 
dependency [com.service.UserService]: expected at least 1 bean which 
qualifies as autowire candidate for this dependency. Dependency 
annotations: {}

------------------- SOLUTION -------------------

我必须将@ComponentScan添加到main方法：

@SpringBootApplication
@ComponentScan("com.serviceImpl, com.service")
public class SpringCrudApplication {

    public static void main(String[] args) {

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

Answer 1

必须通过ComnponentScan找到实现，而不是接口。 因此，如果您的类UserServiceImpl位于包com.serviceImpl中，则必须扫描此包。

包名称看起来很奇怪，包名称只能是小写。 因此，请尝试将程序包重命名为com.service.impl并扫描它。

因为您正在使用@Transactional，所以spring将创建一个实现UserService的代理。因此，您只能注入UserService但不能注册UserServiceImpl。 检查你的代码，可能是你试图在其他地方@Autowire一个UserServiceImpl。

除了您的异常'没有类型的匹配bean ...'之外，堆栈跟踪中通常会出现“无法自动装配”的消息， 春天试图注入什么类型。