//使用 https://api.weixin.qq.com/cgi-bin/material/add_material?access_token=yourtoken&type=thumb
接口进行缩略图进行上传 //这里我是通过postman进行上传的  //获取asstoken 可能会报白名单的问题 ，需要把你获取token的ip 添加到公众号白名单。
记录下返回的thumb_media_id（media_id）

    card := MiniprogramCard{
                Touser: reflect.ValueOf(server.RequestMsg.FromUserName).String(), //需要发送的用户
                //miniprogrampage
                Msgtype: "miniprogrampage",
                Miniprogrampage: MiniProgramPage{
                    Title:          "title",
                    Appid:          "", //微信小程序appid
                    PagePath:       "pages/index/index",  //微信小程序页面地址
                    ThumbMediaId: "A9WJuZt1K57Vs1AQAPmx3JG_G7IGzBS_2sx_WpNSGvU"}, //小程序卡片图片的媒体ID
            }

package main

import (
   "fmt"
   wechat "github.com/silenceper/wechat/v2"
   "github.com/silenceper/wechat/v2/cache"
   offConfig "github.com/silenceper/wechat/v2/officialaccount/config"
   "github.com/silenceper/wechat/v2/officialaccount/message"
   "net/http"
   "reflect"
)

func serveWechat(rw http.ResponseWriter, req *http.Request) {
   wc := wechat.NewWechat()
   //这里本地内存保存access_token，也可选择redis memcache 或者自定cache
   memory := cache.NewMemory()
   cfg := &offConfig.Config{
      AppID:          "",
      AppSecret:      "",
      Token:          "",
      EncodingAESKey: "",
      Cache:          memory,
   }
   officialAccount := wc.GetOfficialAccount(cfg)

   // 传入request和responseWriter
   server := officialAccount.GetServer(req, rw)
   //设置接收消息的处理方法
   server.SetMessageHandler(func(mixMessage *message.MixMessage) *message.Reply {
      //TODO
      //回复消息：演示回复用户发送的消息
      switch mixMessage.MsgType {
      //自动回复消息
      case message.MsgTypeText:
         text := message.NewText(mixMessage.Content)
         return &message.Reply{MsgType: message.MsgTypeText, MsgData: text}
      }
      switch mixMessage.Event {
      //如果是初次订阅回复图文消息
      case message.EventSubscribe:
         //获取token
         miniprogrampagemessage :=  message.NewCustomerMiniprogrampageMessage(reflect.ValueOf(server.RequestMsg.FromUserName).String(),"title","appId","pages/index/index","缩略图id")
         officialAccount.GetCustomerMessageManager().Send(miniprogrampagemessage)
         return &message.Reply{MsgType: message.MsgTypeMiniprogrampage, MsgData: miniprogrampagemessage}
         //根据token 发送客服消息
         
      }
      text := message.NewText(mixMessage.Content)

      return &message.Reply{MsgType: message.MsgTypeText, MsgData: text}
   })
   //处理消息接收以及回复
   err := server.Serve()
   if err != nil {
      fmt.Println(err)
      return
   }
   //发送回复的消息
   server.Send()
}

func main() {
   http.HandleFunc("/", serveWechat)
   fmt.Println("wechat server listener at", ":8001")
   err := http.ListenAndServe(":8001", nil)
   if err != nil {
      fmt.Printf("start server error , err=%v", err)
   }
}