@RequestMapping("/user")
public class UserController {
    
    @Autowired
    private UserService userService;
    
    @GetMapping("/{id}")
    public ModelAndView getUser(@PathVariable("id") int id) {
        User user = userService.getUserById(id);
        ModelAndView modelAndView = new ModelAndView("user");
        modelAndView.addObject("user", user);
        return modelAndView;
    }
    
    @PostMapping("/")
    public String createUser(@ModelAttribute("user") User user) {
        userService.createUser(user);
        return "redirect:/user/" + user.getId();
    }
    
    @PutMapping("/{id}")
    public String updateUser(@PathVariable("id") int id, @ModelAttribute("user") User user) {
        user.setId(id);
        userService.updateUser(user);
        return "redirect:/user/" + id;
    }
    
    @DeleteMapping("/{id}")
    public String deleteUser(@PathVariable("id") int id) {
        userService.deleteUser(id);
        return "redirect:/user";
    }
}

SpringMVC中的模型层如何实现业务逻辑

@Service
public class UserServiceImpl implements UserService {
    
    @Autowired
    private UserDao userDao;
    
    public User getUserById(int id) {
        return userDao.getUserById(id);
    }
    
    public void createUser(User user) {
        userDao.createUser(user);
    }
    
    public void updateUser(User user) {
        userDao.updateUser(user);
    }
    
    public void deleteUser(int id) {
        userDao.deleteUser(id);
    }
}

SpringMVC中的视图层如何展示数据

${user.username}
姓名：${user.name}
年龄：${user.age}