今天遇到一个问题，在数据库层存储的是
“user_floorvarchar(50) NOT NULL DEFAULT '' COMMENT '负责楼层',

但是在PO层我需要将它转为List, 如果写方法去适配的话需要写很多，不管是存储，还是查询，都要去适配，user_floor存储的是用,分隔的字符串

实现

原理：继承BaseTypeHandler，去重写里面的抽象方法

PO

autoResultMap这个属性要加，或者说在yaml中配置了，不然查询出来是null

@Data
@TableName(value = "parxxxxxconfig", autoResultMap = true)
@Accessors(chain = true)
public class PaXXXXXXConfigPO {
     @TableField(value = "user_floor",typeHandler = ListToStringTypeHandler.class)
     private List<Integer> userFloor;
}

handler

import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

public class ListToStringTypeHandler extends BaseTypeHandler<List<Integer>> {

    private static final Logger logger = LoggerFactory.getLogger(ListToStringTypeHandler.class);

    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, List<Integer> parameter, JdbcType jdbcType) throws SQLException {
        String value = parameter.stream()
                .map(String::valueOf)
                .collect(Collectors.joining(","));
        logger.info("Setting parameter: {}", value); // 打印日志
        ps.setString(i, value);
    }

    @Override
    public List<Integer> getNullableResult(ResultSet rs, String columnName) throws SQLException {
        String value = rs.getString(columnName);
        logger.info("Getting result from column {}: {}", columnName, value); // 打印日志
        return convertStringToList(value);
    }

    @Override
    public List<Integer> getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        String value = rs.getString(columnIndex);
        logger.info("Getting result from column index {}: {}", columnIndex, value); // 打印日志
        return convertStringToList(value);
    }

    @Override
    public List<Integer> getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        String value = cs.getString(columnIndex);
        logger.info("Getting result from callable statement: {}", value); // 打印日志
        return convertStringToList(value);
    }

    private List<Integer> convertStringToList(String value) {
        if (value == null || value.isEmpty()) {
            return Collections.emptyList();
        }
        return Arrays.stream(value.split(","))
                .map(String::trim)
                .map(Integer::valueOf)
                .collect(Collectors.toList());
    }
}

mapper

 <resultMap id="xxxxxxConfigMap" type="com.xx.xxx.xxConfigPO">
            <result column="config_id" property="configId"/>

            <result column="user_floor" property="userFloor" typeHandler="com.cf.newbarcode.dao.handler.ListToStringTypeHandler"/>

    </resultMap>