<!--web依赖包，web应用必备-->
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId>
</dependency>

public String addUser(User user) {if (user == null || user.getId() == null || user.getAccount() == null || user.getPassword() == null || user.getEmail() == null) {return "对象或者对象字段不能为空";}if (StringUtils.isEmpty(user.getAccount()) || StringUtils.isEmpty(user.getPassword()) || StringUtils.isEmpty(user.getEmail())) {return "不能输入空字符串";}if (user.getAccount().length() < 6 || user.getAccount().length() > 11) {return "账号长度必须是6-11个字符";}if (user.getPassword().length() < 6 || user.getPassword().length() > 16) {return "密码长度必须是6-16个字符";}if (!Pattern.matches("^[a-zA-Z0-9_-]+@[a-zA-Z0-9_-]+(.[a-zA-Z0-9_-]+)+$", user.getEmail())) {return "邮箱格式不正确";}// 参数校验完毕后这里就写上业务逻辑return "success";}

@Data
public class User {@NotNull(message = "用户id不能为空")private Long id;@NotNull(message = "用户账号不能为空")@Size(min = 6, max = 11, message = "账号长度必须是6-11个字符")private String account;@NotNull(message = "用户密码不能为空")@Size(min = 6, max = 11, message = "密码长度必须是6-16个字符")private String password;@NotNull(message = "用户邮箱不能为空")@Email(message = "邮箱格式不正确")private String email;
}

@RestController
@RequestMapping("user")
public class UserController {@Autowiredprivate UserService userService;@PostMapping("/addUser")public String addUser(@RequestBody @Valid User user, BindingResult bindingResult) {// 如果有参数校验失败，会将错误信息封装成对象组装在BindingResult里for (ObjectError error : bindingResult.getAllErrors()) {return error.getDefaultMessage();}return userService.addUser(user);}
}

public String addUser(User user) {// 直接编写业务逻辑return "success";}

{"account": "12345678","email": "123@qq.com","id": 0,"password": "123"
}

@PostMapping("/addUser")
public String addUser(@RequestBody @Valid User user) {return userService.addUser(user);
}

@RestControllerAdvice
public class ExceptionControllerAdvice {@ExceptionHandler(MethodArgumentNotValidException.class)public String MethodArgumentNotValidExceptionHandler(MethodArgumentNotValidException e) {// 从异常对象中拿到ObjectError对象ObjectError objectError = e.getBindingResult().getAllErrors().get(0);// 然后提取错误提示信息进行返回return objectError.getDefaultMessage();}}

@Getter //只要getter方法，无需setter
public class APIException extends RuntimeException {private int code;private String msg;public APIException() {this(1001, "接口错误");}public APIException(String msg) {this(1001, msg);}public APIException(int code, String msg) {super(msg);this.code = code;this.msg = msg;}
}

@ExceptionHandler(APIException.class)
public String APIExceptionHandler(APIException e) {return e.getMsg();
}

@Getter
public class ResultVO<T> {/*** 状态码，比如1000代表响应成功*/private int code;/*** 响应信息，用来说明响应情况*/private String msg;/*** 响应的具体数据*/private T data;public ResultVO(T data) {this(1000, "success", data);}public ResultVO(int code, String msg, T data) {this.code = code;this.msg = msg;this.data = data;}
}

@ExceptionHandler(APIException.class)
public ResultVO<String> APIExceptionHandler(APIException e) {// 注意哦，这里返回类型是自定义响应体return new ResultVO<>(e.getCode(), "响应失败", e.getMsg());
}@ExceptionHandler(MethodArgumentNotValidException.class)
public ResultVO<String> MethodArgumentNotValidExceptionHandler(MethodArgumentNotValidException e) {ObjectError objectError = e.getBindingResult().getAllErrors().get(0);// 注意哦，这里返回类型是自定义响应体return new ResultVO<>(1001, "参数校验失败", objectError.getDefaultMessage());
}

@GetMapping("/getUser")
public ResultVO<User> getUser() {User user = new User();user.setId(1L);user.setAccount("12345678");user.setPassword("12345678");user.setEmail("123@qq.com");return new ResultVO<>(user);
}

@Getter
public enum ResultCode {SUCCESS(1000, "操作成功"),FAILED(1001, "响应失败"),VALIDATE_FAILED(1002, "参数校验失败"),ERROR(5000, "未知错误");private int code;private String msg;ResultCode(int code, String msg) {this.code = code;this.msg = msg;}}

public ResultVO(T data) {this(ResultCode.SUCCESS, data);
}public ResultVO(ResultCode resultCode, T data) {this.code = resultCode.getCode();this.msg = resultCode.getMsg();this.data = data;
}

@ExceptionHandler(APIException.class)
public ResultVO<String> APIExceptionHandler(APIException e) {// 注意哦，这里传递的响应码枚举return new ResultVO<>(ResultCode.FAILED, e.getMsg());
}@ExceptionHandler(MethodArgumentNotValidException.class)
public ResultVO<String> MethodArgumentNotValidExceptionHandler(MethodArgumentNotValidException e) {ObjectError objectError = e.getBindingResult().getAllErrors().get(0);// 注意哦，这里传递的响应码枚举return new ResultVO<>(ResultCode.VALIDATE_FAILED, objectError.getDefaultMessage());
}

@RestControllerAdvice(basePackages = {"com.rudecrab.demo.controller"}) // 注意哦，这里要加上需要扫描的包
public class ResponseControllerAdvice implements ResponseBodyAdvice<Object> {@Overridepublic boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> aClass) {// 如果接口返回的类型本身就是ResultVO那就没有必要进行额外的操作，返回falsereturn !returnType.getGenericParameterType().equals(ResultVO.class);}@Overridepublic Object beforeBodyWrite(Object data, MethodParameter returnType, MediaType mediaType, Class<? extends HttpMessageConverter<?>> aClass, ServerHttpRequest request, ServerHttpResponse response) {// String类型不能直接包装，所以要进行些特别的处理if (returnType.getGenericParameterType().equals(String.class)) {ObjectMapper objectMapper = new ObjectMapper();try {// 将数据包装在ResultVO里后，再转换为json字符串响应给前端return objectMapper.writeValueAsString(new ResultVO<>(data));} catch (JsonProcessingException e) {throw new APIException("返回String类型错误");}}// 将原本的数据包装在ResultVO里return new ResultVO<>(data);}
}

@GetMapping("/getUser")
public User getUser() {User user = new User();user.setId(1L);user.setAccount("12345678");user.setPassword("12345678");user.setEmail("123@qq.com");// 注意哦，这里是直接返回的User类型，并没有用ResultVO进行包装return user;
}