java 項目 ， controller.java , service.java ???

您好！Java项目通常采用MVC架构，其中Controller层负责接收请求并调用Service层处理业务逻辑，最后将处理结果返回给前端。Service层则负责具体的业务逻辑处理，例如数据的增删改查等操作。下面是一个简单的Java项目Controller层和Service层的示例：

Controller.java：

@RestController
@RequestMapping("/api")
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping("/users")
    public List<User> getAllUsers() {
        return userService.getAllUsers();
    }

    @GetMapping("/users/{id}")
    public User getUserById(@PathVariable Long id) {
        return userService.getUserById(id);
    }

    @PostMapping("/users")
    public User createUser(@RequestBody User user) {
        return userService.createUser(user);
    }

    @PutMapping("/users/{id}")
    public User updateUser(@PathVariable Long id, @RequestBody User user) {
        return userService.updateUser(id, user);
    }

    @DeleteMapping("/users/{id}")
    public void deleteUser(@PathVariable Long id) {
        userService.deleteUser(id);
    }
}

Service.java：

@Service
public class UserService {

    @Autowired
    private UserRepository userRepository;

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

    public User getUserById(Long id) {
        return userRepository.findById(id)
                .orElseThrow(() -> new ResourceNotFoundException("User", "id", id));
    }

    public User createUser(User user) {
        return userRepository.save(user);
    }

    public User updateUser(Long id, User userDetails) {
        User user = userRepository.findById(id)
                .orElseThrow(() -> new ResourceNotFoundException("User", "id", id));

        user.setName(userDetails.getName());
        user.setEmail(userDetails.getEmail());

        return userRepository.save(user);
    }

    public void deleteUser(Long id) {
        User user = userRepository.findById(id)
                .orElseThrow(() -> new ResourceNotFoundException("User", "id", id));

        userRepository.delete(user);
    }
}