SpringMVC中的表现层结果封装

public class Result {
    private Integer code;
    private Object data;
    private String msg;

    public Result() {
    }

    public Result(Integer code, Object data) {
        this.code = code;
        this.data = data;
    }

    public Result(Integer code, Object data, String msg) {
        this.code = code;
        this.data = data;
        this.msg = msg;
    }
}

public class Code {
    public static final Integer INSERT_OK = 20011;
    public static final Integer DELETE_OK = 20021;
    public static final Integer UPDATE_OK = 20031;
    public static final Integer SELECT_OK = 20041;

    public static final Integer INSERT_ERR = 20010;
    public static final Integer DELETE_ERR = 20020;
    public static final Integer UPDATE_ERR = 20030;
    public static final Integer SELECT_ERR = 20040;

    public static final Integer SYSTEM_ERR = 50001;
    public static final Integer SYSTEM_TIMEOUT_ERR = 50002;
    public static final Integer SYSTEM_UNKNOW_ERR = 59999;
    public static final Integer BUSINESS_ERR = 60002;
}

@RestController
@RequestMapping("users")
public class UserController {
    @Autowired
    private UserService userService;

    @PostMapping
    public Result insert(@RequestBody User user) {
        boolean insert = userService.insert(user);
        return new Result(insert ? Code.: Code.INSERT_ERR,insert);
    }

    @PutMapping
    public Result update(@RequestBody User user) {
        boolean update = userService.update(user);
        return new Result(update ? Code.UPDATE_OK : Code.UPDATE_ERR,update);
    }

    @DeleteMapping("/{id}")
    public Result delete(@PathVariable Integer id) {
        boolean delete = userService.delete(id);
        return new Result(delete ? Code.DELETE_OK : Code.DELETE_ERR,delete);
    }

    @GetMapping("/{id}")
    public Result selectById(@PathVariable Integer id) {
        User user = userService.selectById(id);
        Integer code = user != null ? Code.SELECT_OK : Code.SELECT_ERR;
        String msg = user != null ? "" : "查询结果不存在，请重试！";
        return new Result(code,user,msg);
    }

    @GetMapping
    public Result selectAll() {
        List<User> userList = userService.selectAll();
        Integer code = userList != null ? Code.SELECT_OK : Code.SELECT_ERR;
        String msg = userList != null ? "" : "查询结果不存在，请重试！";
        return new Result(code,userList,msg);
    }
}