会话存档 发送的是excel 文件 拉取到的数据变下面这样 

{"msgid":"9712517195034538942_1616143607","action":"send","from":"huangwei","tolist":["xundenghang"],"roomid":"","msgtime":1616143607042,"msgtype":"text","text":{"content":"【未知消息类型】"}}

检测到超过50K 会变上述情况 否则正常