// @Autowired + @Qualifier
@Autowired 
@Qualifier("mysqlDataSource")
private DataSource dataSource;

// @Resource
@Resource(name = "oracleDataSource")
private DataSource dataSource;

// PathVariable
@GetMapping("/users/{id}")
public User getUser(@PathVariable Long id) { ... }

// RequestBody
@PostMapping("/users")
public ResponseEntity<?> createUser(@RequestBody UserDTO userDTO) { ... }

@Entity
@Table(name = "departments")
public class Department {
    @OneToMany(mappedBy = "department")
    private List<Employee> employees;
}

@Entity
public class Employee {
    @ManyToOne
    @JoinColumn(name = "dept_id")
    private Department department;
}

# application.yml
app:
  security:
    enabled: true
    timeout: 300

@Configuration
@ConfigurationProperties(prefix = "app.security")
public class SecurityConfig {
    private boolean enabled;
    private int timeout;
    // getters/setters
}

@Value
@Builder
public class ImmutablePoint {
    private final int x;
    private final int y;
}

// 使用
ImmutablePoint point = ImmutablePoint.builder().x(10).y(20).build();

@Service
public class UserService {
    @Transactional
    public void updateUser(User user) {
        userRepository.save(user);
    }
}

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    @Modifying
    @Query("UPDATE User u SET u.name = ?1 WHERE u.id = ?2")
    int updateNameById(String name, Long id);
}

// 全集成測(cè)試
@SpringBootTest
class UserServiceIntegrationTest {
    @Autowired
    private UserService userService;
}

// 控制層測(cè)試
@WebMvcTest(UserController.class)
class UserControllerTest {
    @MockBean
    private UserService userService;
    @Autowired
    private MockMvc mockMvc;
}