官网：https://baomidou.com/guides/type-handler/

示例：

Java数据类型：List<String>
存入数据库的JSON字符串：["user", "edu-admin"]

User.java

@TableName(autoResultMap = true)
public class User implements Serializable {
    @TableField(typeHandler = JacksonTypeHandler.class)
    private List<String> roles;
}

UserMapper.xml

<resultMap id="BaseResultMap" type="cn.edu.jsu.zjj.model.entity.User">
  <result property="roles" column="roles" typeHandler="cn.edu.jsu.zjj.model.utils.ListToVarcharTypeHandler" jdbcType="VARCHAR"/>
</resultMap>

JSON解析器：

package cn.edu.jsu.zjj.model.utils;

import com.baomidou.mybatisplus.core.toolkit.StringUtils;
import org.apache.ibatis.type.*;

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

@MappedTypes(List.class)
@MappedJdbcTypes(JdbcType.VARCHAR)
public class ListToVarcharTypeHandler implements TypeHandler<List<String>> {

    public void setParameter(PreparedStatement preparedStatement, int i, List<String> strings, JdbcType jdbcType) throws SQLException {
        // 遍历List类型的入参，拼装为String类型，使用Statement对象插入数据库
        StringBuffer sb = new StringBuffer();
        for (int j = 0; j < strings.size(); j++) {
            if (j == strings.size() - 1) {
                sb.append(strings.get(j));
            } else {
                sb.append(strings.get(j)).append(",");
            }
        }
        preparedStatement.setString(i, sb.toString());
    }

    @Override
    public List<String> getResult(ResultSet resultSet, String s) throws SQLException {
        // 获取String类型的结果，使用","分割为List后返回
        String resultString = resultSet.getString(s);
        if (StringUtils.isNotBlank(resultString)) {
            return Arrays.asList(resultString.split(","));
        }
        return null;
    }

    @Override
    public List<String> getResult(ResultSet resultSet, int i) throws SQLException {
        // 获取String类型的结果，使用","分割为List后返回
        String resultString = resultSet.getString(i);
        if (StringUtils.isNotBlank(resultString)) {
            return Arrays.asList(resultString.split(","));
        }
        return null;
    }

    @Override
    public List<String> getResult(CallableStatement callableStatement, int i) throws SQLException {
        // 获取String类型的结果，使用","分割为List后返回
        String resultString = callableStatement.getString(i);
        if (StringUtils.isNotBlank(resultString)) {
            return Arrays.asList(resultString.split(","));
        }
        return null;
    }
}