MyBatisPlus自定义JsonTypeHandler实现自动转化JSON问题

@Service
public class DingRobotMsgServiceImpl extends ServiceImpl<DingRobotMsgMapper, DingRobotMsg> implements IDingRobotMsgService {
 
    @Autowired
    private DingRobotMsgMapper dingRobotMsgMapper;
 
    @Override
    public void insertRobotMsg(DingRobotMsg dingRobotMsg) {
        // 新增
        dingRobotMsg.setState("1");
        if (dingRobotMsg.getMsgtype().equals("text") || dingRobotMsg.getMsgtype().equals("file")) {
            dingRobotMsgMapper.insert(dingRobotMsg);
        } else {
            // TODO: 类型错误！
        }
    }
}

@Data
@TableName("t_dingtalk_recemsg")
public class DingRobotMsg {
    @TableId(value = "id", type = IdType.AUTO)
    private Long id;
 
    @TableField(value = "msgtype")
    private String msgtype;
 
    private Content content;
 
    private Text text;
 
    // ...
}

/**
 * 对象字段转存为Json类型
 * @param <T>
 */
@MappedTypes({Text.class, Content.class})
public class JsonTypeHandler<T> extends BaseTypeHandler<T> {
 
    private final Class<T> type;
 
    public JsonTypeHandler(Class<T> type) {
        if (type == null) {
            throw new IllegalArgumentException("Type argument cannot be null");
        }
        this.type = type;
    }
 
    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException {
        // 将对象转换为JSON字符串并设置到PreparedStatement中
        ps.setString(i, JSON.toJSONString(parameter));
    }
 
    @Override
    public T getNullableResult(ResultSet rs, String columnName) throws SQLException {
        // 从ResultSet中获取JSON字符串并转换为指定类型的对象
        String jsonString = rs.getString(columnName);
        return JSON.parseObject(jsonString, type);
    }
 
    @Override
    public T getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        // 从ResultSet中获取JSON字符串并转换为指定类型的对象
        String jsonString = rs.getString(columnIndex);
        return JSON.parseObject(jsonString, type);
    }
 
    @Override
    public T getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        // 从CallableStatement中获取JSON字符串并转换为指定类型的对象
        String jsonString = cs.getString(columnIndex);
        return JSON.parseObject(jsonString, type);
    }
}

@TableField(typeHandler = JsonTypeHandler.class)
private Content content;
 
@TableField(typeHandler = JsonTypeHandler.class)
private Text text;