mybatisplus.MetaObjectHandler；元对象字段填充控制器抽象类，实现公共字段自动写入

程序员文章站 2022-03-27 09:22:45

* Licensed under the Apache License, Version 2.0 (the "License"); * you...

先放一张表生成策略对应的结果

值	描述
DEFAULT	默认不处理
INSERT	插入时填充字段
UPDATE	更新时填充字段
INSERT_UPDATE	插入和更新时填充字段

/*
 * Copyright (c) 2011-2014, hubin (jobob@qq.com).
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.baomidou.mybatisplus.annotation;

/**
 * <p>
 * 字段填充策略枚举类
 * </p>
 *
 * @author hubin
 * @since 2017-06-27
 */
public enum FieldFill {
    /**
     * 默认不处理
     */
    DEFAULT,
    /**
     * 插入填充字段
     */
    INSERT,
    /**
     * 更新填充字段
     */
    UPDATE,
    /**
     * 插入和更新填充字段
     */
    INSERT_UPDATE
}

此处需要注意一下,如果MyBatisPlus中有一些公共字段例如修改时间,创建时间,乐观锁等等

创建是采用INSERT方案

修改时采用UPDATE

在修改时注意,使用MyBatis-Plus的update方法,传入QueryWrapper或者直接传null

用updateById会出现策略不生效的情况

贴上实现生成策略接口的代码

package com.mengxiangnongfu.project.configure.mybatisplus.tools;

import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import com.mengxiangnongfu.project.util.TimeHelper;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;

/**
 * 自动填充处理类
 * mybatis-plus 3.3版本以上 使用注解的方式
 * https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/89450006?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.channel_param&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.channel_param
 *
 * @author Yang
 * @version 1.0
 * @see
 **/
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {

    @Override
    public void insertFill(MetaObject metaObject) {　　　　　　//version是字段名 第二个参数是填充的数据
        this.setFieldValByName("version", new Long(0), metaObject);
        this.setFieldValByName("createTime", TimeHelper.getCurrentTime14(), metaObject);
        this.setFieldValByName("updateTime", TimeHelper.getCurrentTime14(), metaObject);
    }

    @Override
    public void updateFill(MetaObject metaObject) {
        this.setFieldValByName("updateTime", TimeHelper.getCurrentTime14(), metaObject);
    }
}

package cn.king.core.base;

import com.baomidou.mybatisplus.annotation.FieldFill;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableLogic;
import com.baomidou.mybatisplus.annotation.Version;
import lombok.Data;

import java.io.Serializable;
import java.util.Date;

/**
 * 实体基类
 *
 * @description:
 * @author: Admin
 * @create: 2020-12-27 13:39
 **/
@Data
public class BaseEntity implements Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * 创建时间
     */
    private Date createTime;

    /**
     * 更新时间
     */
    @TableField(update = "now()", fill = FieldFill.UPDATE)
    private Date updateTime;

    /**
     * 软删除（1:存在、2:已删除）
     */
    @TableLogic
    private Integer isDeleted;

    /**
     * 版本
     */
    @Version
    private Integer version;
}

/*
 * Copyright (c) 2011-2020, hubin (jobob@qq.com).
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.baomidou.mybatisplus.core.handlers;

import com.baomidou.mybatisplus.core.toolkit.Constants;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.SystemMetaObject;

/**
 * <p>
 * 元对象字段填充控制器抽象类，实现公共字段自动写入
 * </p>
 *
 * @author hubin
 * @since 2016-08-28
 */
public interface MetaObjectHandler {

    /**
     * 插入元对象字段填充（用于插入时对公共字段的填充）
     *
     * @param metaObject 元对象
     */
    void insertFill(MetaObject metaObject);

    /**
     * 更新元对象字段填充（用于更新时对公共字段的填充）
     *
     * @param metaObject 元对象
     */
    void updateFill(MetaObject metaObject);

    /**
     * <p>
     * Common method to set value for java bean.
     * </p>
     * <p>
     * 如果包含前缀 et 使用该方法，否则可以直接 metaObject.setValue(fieldName, fieldVal);
     * </p>
     *
     * @param fieldName  java bean property name
     * @param fieldVal   java bean property value
     * @param metaObject meta object parameter
     */
    default MetaObjectHandler setFieldValByName(String fieldName, Object fieldVal, MetaObject metaObject) {
        if (metaObject.hasSetter(fieldName) && metaObject.hasGetter(fieldName)) {
            metaObject.setValue(fieldName, fieldVal);
        } else if (metaObject.hasGetter(Constants.ENTITY)) {
            Object et = metaObject.getValue(Constants.ENTITY);
            if (et != null) {
                MetaObject etMeta = SystemMetaObject.forObject(et);
                if (etMeta.hasSetter(fieldName)) {
                    etMeta.setValue(fieldName, fieldVal);
                }
            }
        }
        return this;
    }

    /**
     * <p>
     * get value from java bean by propertyName
     * </p>
     * <p>
     * 如果包含前缀 et 使用该方法，否则可以直接 metaObject.setValue(fieldName, fieldVal);
     * </p>
     *
     * @param fieldName  java bean property name
     * @param metaObject parameter wrapper
     * @return 字段值
     */
    default Object getFieldValByName(String fieldName, MetaObject metaObject) {
        if (metaObject.hasGetter(fieldName)) {
            return metaObject.getValue(fieldName);
        } else if (metaObject.hasGetter(Constants.ENTITY_SPOT + fieldName)) {
            return metaObject.getValue(Constants.ENTITY_SPOT + fieldName);
        }
        return null;
    }

    /**
     * 是否开启了插入填充
     */
    default boolean openInsertFill() {
        return true;
    }

    /**
     * 是否开启了更新填充
     */
    default boolean openUpdateFill() {
        return true;
    }
}

本文地址：https://blog.csdn.net/hhj13978064496/article/details/111997934