MyBatis-Plus实现公共字段自动填充功能详解

@TableField(fill = FieldFill.INSERT)//插入时填充字段
private LocalDateTime createTime;
 
@TableField(fill = FieldFill.INSERT_UPDATE)//插入、更新时填充字段
private LocalDateTime updateTime;
 
@TableField(fill = FieldFill.INSERT)//插入时填充字段
private Long createUser;

@TableField(fill = FieldFill.INSERT_UPDATE)//插入、更新时填充字段
private Long updateUser;

package com.lyq.reggie.common;

import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;
import java.time.LocalDateTime;


@Component
@Slf4j
public class MyMetaObjecthandler implements MetaObjectHandler {
    
    @Override
    public void insertFill(MetaObject metaObject) {
        log.info("公共字段自动填充[insert]...");
        log.info(metaObject.toString());
        metaObject.setValue("createTime", LocalDateTime.now());
        metaObject.setValue("updateTime",LocalDateTime.now());
        metaObject.setValue("createUser", BaseContext.getCurrentId());
        metaObject.setValue("updateUser",BaseContext.getCurrentId());
    }

    
    @Override
    public void updateFill(MetaObject metaObject) {
        log.info("公共字段自动填充[update]...");
        log.info(metaObject.toString());

        long id = Thread.currentThread().getId();
        log.info("线程id为：{}",id);

        metaObject.setValue("updateTime",LocalDateTime.now());
        metaObject.setValue("updateUser",BaseContext.getCurrentId());
    }
}

@Configuration
public class MybatisPlusConfig {
    
    @Bean
    public UpdateInterceptor updateInterceptor() {
        return new UpdateInterceptor();
    }
}

package com.lyq.jsoup.config.MybatisPlusConfig;
import com.baomidou.mybatisplus.extension.handlers.AbstractSqlParserHandler;
import org.apache.commons.lang3.ArrayUtils;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlCommandType;
import org.apache.ibatis.plugin.*;

import java.lang.reflect.Field;
import java.sql.Timestamp;
import java.util.Map;
import java.util.Objects;
import java.util.Properties;


@Intercepts(value = {@Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class})})
public class UpdateInterceptor extends AbstractSqlParserHandler implements Interceptor {

    
    private static final String CREATE_TIME = "createTime";
    
    private static final String UPDATE_TIME = "updateTime";

    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        MappedStatement mappedStatement = (MappedStatement) invocation.getArgs()[0];
        // SQL操作命令
        SqlCommandType sqlCommandType = mappedStatement.getSqlCommandType();
        // 获取新增或修改的对象参数
        Object parameter = invocation.getArgs()[1];
        // 获取对象中所有的私有成员变量（对应表字段）
        Field[] declaredFields = parameter.getClass().getDeclaredFields();
        if (parameter.getClass().getSuperclass() != null) {
            Field[] superField = parameter.getClass().getSuperclass().getDeclaredFields();
            declaredFields = ArrayUtils.addAll(declaredFields, superField);
        }
        // mybatis plus判断
        boolean plus= parameter.getClass().getDeclaredFields().length == 1 && parameter.getClass().getDeclaredFields()[0].getName().equals("serialVersionUID");

        //兼容mybatis plus
        if (plus) {
            Map<String, Object> updateParam = (Map<String, Object>) parameter;
            Class<?> updateParamType = updateParam.get(updateParam.keySet().iterator().next()).getClass();
            declaredFields = updateParamType.getDeclaredFields();
            if (updateParamType.getSuperclass() != null) {
                Field[] superField = updateParamType.getSuperclass().getDeclaredFields();
                declaredFields = ArrayUtils.addAll(declaredFields, superField);
            }
        }
        String fieldName = null;
        for (Field field : declaredFields) {
            fieldName = field.getName();
            if (Objects.equals(CREATE_TIME, fieldName)) {
                if (SqlCommandType.INSERT.equals(sqlCommandType)) {
                    field.setAccessible(true);
                    field.set(parameter, new Timestamp(System.currentTimeMillis()));
                }
            }
            if (Objects.equals(UPDATE_TIME, fieldName)) {
                if (SqlCommandType.INSERT.equals(sqlCommandType) || SqlCommandType.UPDATE.equals(sqlCommandType)) {
                    field.setAccessible(true);
                    //兼容mybatis plus的update
                    if (plus) {
                        Map<String, Object> updateParam = (Map<String, Object>) parameter;
                        field.set(updateParam.get(updateParam.keySet().iterator().next()), new Timestamp(System.currentTimeMillis()));
                    } else {
                        field.set(parameter, new Timestamp(System.currentTimeMillis()));
                    }
                }
            }
        }
        return invocation.proceed();
    }

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

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