mybatisPlus如何使用MetaObjectHandler对字段进行更新

/*所有domain类的通用字段*/
@Data
public class BaseDomain implements Serializable {

    /*这几个值是公用的，在 INSERT/UPDATE 操作的时候，会去自动更新这几个值，具体实现看 MyMetaObjecthandler*/
    @TableField(fill = FieldFill.INSERT_UPDATE)
    public Integer yn;
    @TableField(fill = FieldFill.INSERT_UPDATE)
    public String creator;
    @TableField(fill = FieldFill.INSERT_UPDATE)
    public String updater;
    @TableField(fill = FieldFill.INSERT_UPDATE)
    public Date createTime;
    @TableField(fill = FieldFill.INSERT_UPDATE)
    public Date updateTime;

}

@TableName(value ="student")
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student extends BaseDomain {

    @TableId(type = IdType.AUTO)
    private Integer id;
    private String studentName;
    private String studentPassword;
    private String teacheruuid;
    private String phone;
    private String address;

    @TableField(exist = false)
    private static final long serialVersionUID = 1L;

    @Override
    public boolean equals(Object that) {
        if (this == that) {
            return true;
        }
        if (that == null) {
            return false;
        }
        if (getClass() != that.getClass()) {
            return false;
        }
        Student other = (Student) that;
        return (this.getId() == null ? other.getId() == null : this.getId().equals(other.getId()))
            && (this.getStudentName() == null ? other.getStudentName() == null : this.getStudentName().equals(other.getStudentName()))
            && (this.getStudentPassword() == null ? other.getStudentPassword() == null : this.getStudentPassword().equals(other.getStudentPassword()))
            && (this.getTeacheruuid() == null ? other.getTeacheruuid() == null : this.getTeacheruuid().equals(other.getTeacheruuid()))
            && (this.getPhone() == null ? other.getPhone() == null : this.getPhone().equals(other.getPhone()))
            && (this.getAddress() == null ? other.getAddress() == null : this.getAddress().equals(other.getAddress()))
            && (this.getYn() == null ? other.getYn() == null : this.getYn().equals(other.getYn()))
            && (this.getCreator() == null ? other.getCreator() == null : this.getCreator().equals(other.getCreator()))
            && (this.getUpdater() == null ? other.getUpdater() == null : this.getUpdater().equals(other.getUpdater()))
            && (this.getCreateTime() == null ? other.getCreateTime() == null : this.getCreateTime().equals(other.getCreateTime()))
            && (this.getUpdateTime() == null ? other.getUpdateTime() == null : this.getUpdateTime().equals(other.getUpdateTime()));
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((getId() == null) ? 0 : getId().hashCode());
        result = prime * result + ((getStudentName() == null) ? 0 : getStudentName().hashCode());
        result = prime * result + ((getStudentPassword() == null) ? 0 : getStudentPassword().hashCode());
        result = prime * result + ((getTeacheruuid() == null) ? 0 : getTeacheruuid().hashCode());
        result = prime * result + ((getPhone() == null) ? 0 : getPhone().hashCode());
        result = prime * result + ((getAddress() == null) ? 0 : getAddress().hashCode());
        result = prime * result + ((getYn() == null) ? 0 : getYn().hashCode());
        result = prime * result + ((getCreator() == null) ? 0 : getCreator().hashCode());
        result = prime * result + ((getUpdater() == null) ? 0 : getUpdater().hashCode());
        result = prime * result + ((getCreateTime() == null) ? 0 : getCreateTime().hashCode());
        result = prime * result + ((getUpdateTime() == null) ? 0 : getUpdateTime().hashCode());
        return result;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append(getClass().getSimpleName());
        sb.append(" [");
        sb.append("Hash = ").append(hashCode());
        sb.append(", id=").append(id);
        sb.append(", studentName=").append(studentName);
        sb.append(", studentPassword=").append(studentPassword);
        sb.append(", teacheruuid=").append(teacheruuid);
        sb.append(", phone=").append(phone);
        sb.append(", address=").append(address);
        sb.append(", yn=").append(yn);
        sb.append(", creator=").append(creator);
        sb.append(", updater=").append(updater);
        sb.append(", createTime=").append(createTime);
        sb.append(", updateTime=").append(updateTime);
        sb.append(", serialVersionUID=").append(serialVersionUID);
        sb.append("]");
        return sb.toString();
    }
}

/*该类的作用是：
 * 为实体类上添加了 INSERT_UPDATE 设置的类的 新增或者是更新操作做自动的属性填充*/
 * 
@Component //注意这里需要将其放入容器中
public class MyMetaObjecthandler implements MetaObjectHandler {
//		公共的属性有这几个
//    public Integer yn;
//    public String creator;
//    public String updater;
//    public Date createTime;
//    public Date updateTime;
    @Override
    public void insertFill(MetaObject metaObject) {
        Date now = new Date();
        /*如果对象在进行插入操作的时候，对象中的 yn 是没有值的，此时才需要给他进行默认的填充*/
        if (metaObject.getValue("yn") == null) {
            setFieldValByName("yn", 1, metaObject);
        }
        if (metaObject.getValue("creator") == null) {
            /*这里可以结合 security 的上下文来获取操作人 我这里写的简单了，就直接使用 admin 来赋值*/
            setFieldValByName("creator", "admin", metaObject);
        }
        if (metaObject.getValue("updater") == null) {
            /*这里可以结合 security 的上下文来获取操作人 我这里写的简单了，就直接使用 admin 来赋值*/
            setFieldValByName("updater", "admin", metaObject);
        }
        if (metaObject.getValue("createTime") == null) {
            setFieldValByName("createTime", now, metaObject);
        }
        if (metaObject.getValue("updateTime") == null) {
            setFieldValByName("updateTime", now, metaObject);
        }
    }

    @Override
    public void updateFill(MetaObject metaObject) {

        /*更新的时候 逻辑就不太一样了 更新的前提是有一个对象，那么该对象的一些值是不能随便乱动的，
         * 就比如yn，而更新人和更新时间则可以变化*/
        if (metaObject.getValue("updater") == null) {
            /*这里可以结合 security 的上下文来获取操作人 我这里写的简单了，就直接使用 admin 来赋值*/
            setFieldValByName("updater", "admin1231231", metaObject);
        }
        if (metaObject.getValue("updateTime") == null) {
            setFieldValByName("updateTime", new Date(), metaObject);
        }
    }
}

        if ("com.example.jiubodou.domain.Student".equals( metaObject.getOriginalObject().getClass().getName()) ) {
 Date now = new Date();
        /*如果对象在进行插入操作的时候，对象中的 yn 是没有值的，此时才需要给他进行默认的填充*/
        if (metaObject.getValue("yn") == null) {
            setFieldValByName("yn", 1, metaObject);
        }
        if (metaObject.getValue("creator") == null) {
            /*这里可以结合 security 的上下文来获取操作人 我这里写的简单了，就直接使用 admin 来赋值*/
            setFieldValByName("creator", "admin", metaObject);
        }
        if (metaObject.getValue("updater") == null) {
            /*这里可以结合 security 的上下文来获取操作人 我这里写的简单了，就直接使用 admin 来赋值*/
            setFieldValByName("updater", "admin", metaObject);
        }
        if (metaObject.getValue("createTime") == null) {
            setFieldValByName("createTime", now, metaObject);
        }
        if (metaObject.getValue("updateTime") == null) {
            setFieldValByName("updateTime", now, metaObject);
        }     
}