请写一下ssm框架中controller层的代码

以下是一个简单的 SSM 框架中 Controller 层的示例代码：

@Controller
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping(value = "/{id}", method = RequestMethod.GET)
    public String getUserById(@PathVariable("id") int id, Model model) {
        User user = userService.getUserById(id);
        model.addAttribute("user", user);
        return "user";
    }

    @RequestMapping(value = "/add", method = RequestMethod.POST)
    public String addUser(@ModelAttribute("user") User user) {
        userService.addUser(user);
        return "redirect:/user/" + user.getId();
    }

    @RequestMapping(value = "/{id}", method = RequestMethod.PUT)
    public String updateUser(@PathVariable("id") int id, @ModelAttribute("user") User user) {
        user.setId(id);
        userService.updateUser(user);
        return "redirect:/user/" + id;
    }

    @RequestMapping(value = "/{id}", method = RequestMethod.DELETE)
    public String deleteUser(@PathVariable("id") int id) {
        userService.deleteUser(id);
        return "redirect:/user";
    }
}

注意，这只是一个示例代码，实际上 Controller 层的代码会根据具体的业务需求而有所不同。