Entity class design for calculating age based on birthday

package com.szxs.bean.vo;

import com.fasterxml.jackson.annotation.JsonFormat;
import org.springframework.data.annotation.Id;
import org.springframework.data.elasticsearch.annotations.Document;
import org.springframework.data.elasticsearch.annotations.Field;
import org.springframework.data.elasticsearch.annotations.FieldType;
import org.springframework.format.annotation.DateTimeFormat;

import java.util.Date;

@Document(indexName = "staff", type = "staff", replicas = 1, shards = 4)
public class StaffVo {

    @Id
    private Integer id;
    @Field(type = FieldType.Keyword)
    private String userName;
    @Field(type = FieldType.Keyword)
    private String password;
    @Field(type = FieldType.Text, analyzer = "standard")
    private String realName;
    @Field(type = FieldType.Integer)
    private Integer gender;
    @Field(type = FieldType.Date)
    @DateTimeFormat(pattern = "yyyy-MM-dd")
    @JsonFormat(pattern = "yyyy-MM-dd", timezone = "GMT+8")
    private Date birthday;
    @Field(type = FieldType.Keyword)
    private String phone;
    @Field(type = FieldType.Text, analyzer = "ik_smart")
    private String address;
    @Field(type = FieldType.Integer)
    private Integer roleId;

    @Field(type = FieldType.Keyword)
    private String genderName;
    @Field(type = FieldType.Text, analyzer = "ik_smart")
    private String roleName;
    @Field(type = FieldType.Integer)
    private Integer age;

    @Override
    public String toString() {
        return "StaffVo{" +
                "id=" + id +
                ", userName='" + userName + '\'' +
                ", password='" + password + '\'' +
                ", realName='" + realName + '\'' +
                ", gender=" + gender +
                ", birthday=" + birthday +
                ", phone='" + phone + '\'' +
                ", address='" + address + '\'' +
                ", roleId=" + roleId +
                ", genderName='" + genderName + '\'' +
                ", roleName='" + roleName + '\'' +
                ", age=" + age +
                '}';
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getRealName() {
        return realName;
    }

    public void setRealName(String realName) {
        this.realName = realName;
    }

    public Integer getGender() {
        return gender;
    }

    public void setGender(Integer gender) {
        this.gender = gender;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
        setAge();
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public Integer getRoleId() {
        return roleId;
    }

    public void setRoleId(Integer roleId) {
        this.roleId = roleId;
    }

    public String getGenderName() {
        return genderName;
    }

    public void setGenderName(String genderName) {
        this.genderName = genderName;
    }

    public String getRoleName() {
        return roleName;
    }

    public void setRoleName(String roleName) {
        this.roleName = roleName;
    }

    public Integer getAge() {
        return age;
    }

    private void setAge() {
        // Get the current time 
        Date now = new Date();

        // Calculate base age 
        age = now.getYear() - birthday.getYear();

        // Judge ,  month 
        if (now.getMonth() < birthday.getMonth()){
            age--;
        }else if (now.getMonth() == birthday.getMonth()){
            // Judge ,  Japan 
            if (now.getDate() < birthday.getDate()){
                age--;
            }
        }
    }
}