Mybatis Plus实现字段默认值填充（不使用@TableField）

最新推荐文章于 2025-02-28 17:20:23 发布

原创最新推荐文章于 2025-02-28 17:20:23 发布 · 1k 阅读

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背景：

发现项目很多entity的createTime、updateTime没有进行维护。想通过框架层面进行拓展实现自动填充数据。

    @ApiModelProperty("创建人")
    private String creator;

    @ApiModelProperty("创建时间")
    private LocalDateTime createTime;

    @ApiModelProperty("修改人")
    private String modifier;

    @ApiModelProperty("修改时间")
    private LocalDateTime modifyTime;

方案一：

通过实现MetaObjectHandler进行实现

步骤一：自定义实现 MetaObjectHandler

@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
    @Override
    public void insertFill(MetaObject metaObject) {
        LocalDateTime now = LocalDateTime.now();
        String userId = LoginUserContext.getUserInfo().getId();
        this.strictInsertFill(metaObject, "creator", String.class, userId);
        this.strictInsertFill(metaObject, "create_time", LocalDateTime.class, now);
        this.strictInsertFill(metaObject, "createTime", LocalDateTime.class, now);
        this.strictInsertFill(metaObject, "modifier", String.class, userId);
        this.strictInsertFill(metaObject, "modifyTime", LocalDateTime.class, now);
    }

    @Override
    public void updateFill(MetaObject metaObject) {
        LocalDateTime now = LocalDateTime.now();
        String userId = LoginUserContext.getUserInfo().getId();
        this.strictInsertFill(metaObject, "modifier", String.class, userId);
        this.strictInsertFill(metaObject, "modifyTime", LocalDateTime.class, now);
    }
}

步骤二：实体类Entity上加@TableField注解

	@ApiModelProperty("创建人")
    @TableField(fill = FieldFill.INSERT)
    private String creator;

    @ApiModelProperty("创建时间")
    @TableField(fill = FieldFill.INSERT)
    private LocalDateTime createTime;

    @ApiModelProperty("修改人")
    @TableField(fill = FieldFill.UPDATE)
    private String modifier;

    @ApiModelProperty("修改时间")
    @TableField(fill = FieldFill.UPDATE)
    private LocalDateTime modifyTime;

两个步骤缺一不可，我的MP版本是3.5.1，这个版本里，并不支持没有@TableField(fill=XXX)的时候触发自动填充

并且理论上是只要在任意字段上加了@TableField(fill =XXX)就可以了，用不着都使用这个注解。不过还是建议加上，别误导其他小伙伴了

可以看文章后面，为什么没加这个注解就不生效！

方案二

使用MP拦截器不使用@TableField

步骤一：定义拦截器

package com.alin.db.handler;

import com.alin.common.handler.LoginUserContext;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.plugin.*;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.time.LocalDateTime;
import java.util.Map;
import java.util.Properties;


@Intercepts({@Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class})})
@Slf4j
public class MpInterceptor implements Interceptor {

    @Override
    public Object intercept(Invocation invocation) throws InvocationTargetException, IllegalAccessException {
        try {
            Object[] args = invocation.getArgs();
            if (args.length > 1) {
                Object parameter = args[1];
                MappedStatement mappedStatement = (MappedStatement) args[0];
                String sqlCommandType = mappedStatement.getSqlCommandType().name();
                if ("INSERT".equals(sqlCommandType)) {
                    LocalDateTime now = LocalDateTime.now();
                    // 获取当前用户登录id
                    String userId = LoginUserContext.getUserInfo().getId();
                    this.insertFill(parameter, "creator", userId);
                    this.insertFill(parameter, "createTime", now);
                    this.insertFill(parameter, "modifier", userId);
                    this.insertFill(parameter, "modifyTime", now);
                } else if ("UPDATE".equals(sqlCommandType)) {
                    LocalDateTime now = LocalDateTime.now();
                    String userId = LoginUserContext.getUserInfo().getId();
                    this.updateFill(parameter, "modifier", userId);
                    this.updateFill(parameter, "modifyTime", now);
                }
            }
        } catch (Exception e) {
            log.error("尝试填充默认值失败", e);
        }
        return invocation.proceed();
    }


    private void insertFill(Object object, String fieldName, Object value) throws IllegalAccessException {
        Field createTimeField = this.findField(object, fieldName);
        if (createTimeField != null) {
            createTimeField.setAccessible(true);
            if (createTimeField.get(object) == null) {  // 值为空才填充
                createTimeField.set(object, value);
            }
        }
    }

    private void updateFill(Object object, String fieldName, Object value) throws IllegalAccessException {
        if (object instanceof Map) {
            Map objectMap = (Map) object;
            object = objectMap.get("param1");
        }
        Field updateTimeField = this.findField(object, fieldName);
        if (updateTimeField != null) {
            updateTimeField.setAccessible(true);
            if (updateTimeField.get(object) == null) {  // 值为空才填充
                updateTimeField.set(object, value);
            }
        }
    }

    private Field findField(Object object, String fieldName) {
        Class<?> clazz = object.getClass();
        while (clazz != null) {
            try {
                return clazz.getDeclaredField(fieldName);
            } catch (NoSuchFieldException e) {
                clazz = clazz.getSuperclass();
            }
        }
        return null;
    }

    @Override
    public Object plugin(Object target) {
        return target instanceof Executor ? Plugin.wrap(target, this) : target;
    }

    @Override
    public void setProperties(Properties properties) {
    }
}

拦截器被Bean扫描到就可以了。