https://developers.weixin.qq.com/miniprogram/dev/api/file/wx.openDocument.htmlhttps://developers.weixin.qq.com/miniprogram/dev/framework/https://developers.weixin.qq.com/miniprogram/dev/framework/open-ability/url-scheme.htmlhttps://developers.weixin.qq.com/miniprogram/dev/framework/open-ability/url-scheme.html
查看要打开的文件是否过大，如果文件比较大，可以加个loading。