自定义注解实现对用户名的存在验证

自定义注解实现对用户名的存在验证

• 创建UserNameExistAnnotation

  @Retention(RetentionPolicy.RUNTIME)
  @Target({ElementType.METHOD,ElementType.FIELD})
  @Constraint(validatedBy = UserNameExistValidator.class)
  public @interface UserNameExistAnnotation {
    String message() default "出错了！！！";
    Class<?>[] groups() default {};
    Class<?extends Payload>[] payload() default {};
  }
  

• 创建UserNameExistValidator类

  public class UserNameExistValidator implements ConstraintValidator<UserNameExistAnnotation,String> {
      @Autowired
      private UserMapper userMapper;
  
      public void initialize(UserNameExistAnnotation constraintAnnotation){
          System.out.println("UserNameExistValidator 初始化了");
      }
      public boolean isValid(String value, ConstraintValidatorContext contrxt){
          //查询是否存在该用户名
          User user=userMapper.queryUserByUsername(value);
          if(user!=null){
              System.out.println(ReflectionToStringBuilder.toString(user, ToStringStyle.MULTI_LINE_STYLE));
              return false;
          }
          return true;
      }
  }
  

• 在UserVo的username字段上添加@UserNameExistAnnotation(message="该用户名已存在")注解

  
  public class UserVo {
  
      private Integer id;
  
      @Length(min=2,max=18,message="请输入2-18位之间的用户名")
      @UserNameExistAnnotation(message="该用户名已存在")
      private String username;
  
      @Pattern(regexp = "[1-9]([0-9]{2,10})",message = "请输入6-16位之间的任意数字字母或者-_")
      private String password;
  
      @Min(value = 12,message = "年龄必须满足18岁以上")
      private Integer age;
  
      @Past(message = "生日必须是过去的日期")
      private Date birthday;
  
      @NotNull
      private String email;
  
      ...
  }
  
  

• 启动验证
  • 在传入对象的前面添加@Valid注解,添加BindingResult收集错误信息，取消spring对错误URL的自动拦截

  @PostMapping
  public JsonResult insertUser(@Valid @RequestBody UserVo vo,BindingResult bindingResult){
      bindingResult.getAllErrors().forEach(objectError -> {
          FieldError fieldError=(FieldError)objectError;
          System.out.println(fieldError.getField()+" : "+fieldError.getDefaultMessage());
      });
      System.out.println(vo);
      return JsonResult.isOk(vo);
  }