https://api.weixin.qq.com/cityservice/face/identify/getimage获取的数据转化为base64为eyJlcnJjb2RlIjo0ODAwMSwiZXJybXNnIjoiYXBpIHVuYXV0aG9yaXplZCByaWQ6IDYyMzk5Njc2LTNmZjIzZmViLTcwYjVlNTgxIn0=，结果不能显示