https://developers.weixin.qq.com/doc/offiaccount/Asset_Management/Adding_Permanent_Assets.htmlhttps://developers.weixin.qq.com/doc/offiaccount/Asset_Management/Adding_Permanent_Assets.html 素材上传到底要怎么上传？ access_token是啥怎么获取？ 通过curl上传的图片参数在哪？