Java 约束注解

public class UserInfo {
    @NotNull(message = "用户ID不能为空 ")
    private Integer id;
    @NotEmpty(message = "用户名不能为空")
    private String username;
    /**
     * NotBlank 会自动去掉前后空格
     */
    @NotBlank(message = "用户密码不能为空")
    @Length(min = 6, max = 20, message = "密码不能少于6位多于20位")
    private String password;
    @Email(message = "格式必须为有效邮箱")
    private String email;
    @Min(value = 18, message = "年龄不能小于18")
    @Max(value = 60, message = "年龄不能大于60")
    private Integer age;
    @Size(min = 1, message = "不能少于一个好友")
    private List<UserInfo> friends;
    private String phone;
    @Past(message = "生日不能为未来日期")
    private LocalDate date;
}

    @Size(min = 1, message = "不能少于一个好友")
@Size(min = 1, message = "不能少于一个好友")
private List<@Valid  UserInfo> friends; // 这样就能实现级联验证了


public class UserInfo {
    // 登录场景
    public interface LoginGroup{}
    // 注册场景
    public interface RegisterGroup{}

    @NotNull(message = "用户ID不能为空", groups = LoginGroup.class)
    private Integer id;
    @NotEmpty(message = "用户名不能为空")
    private String username;
    /**
     * NotBlank 会自动去掉前后空格
     */
    @NotBlank(message = "用户密码不能为空")
    @Length(min = 6, max = 20, message = "密码不能少于6位多于20位")
    private String password;
    @NotNull(message = "邮箱不能为空", groups = RegisterGroup.class)
    @Email(message = "格式必须为有效邮箱")
    private String email;
}


// 登录场景
public interface LoginGroup{}
// 注册场景
public interface RegisterGroup{}
// 组排序，先验证登录场景再验证注册，再是默认(有些属性没有标注LoginGroup还是RegisterGroup)
@GroupSequence({LoginGroup.class, RegisterGroup.class, Default.class})
public interface Group{}