微信内容安全，参考代码

wechat_imgSecCheck_Demo.js

// 微信小程序，内容安全示例代码
const qiniuUploader = require("../../utils/qiniuUploader.js"); // https://github.com/gpake/qiniu-wxapp-sdk
const wittcism = require('../../utils/wittcism.js') // API

Page({
    data: {},
    onShow() {},
    change_avatar() {
        qiniuUploader.upload(filePath, (res) => {
            var original_qiniu_link = res.qiniu_url
            var link = 'https://img.wittcism.com/' + res.qiniu_url + '?imageView2/2/w/740/h/1324';
            var params = {
                url: link
            }
            wittcism.imgSecCheckByURL(params).then(data => {
                if (data['errmsg'] == 'ok') {
                    // 图片没问题
                    wx.hideLoading();
                    that.update_user_avatar(original_qiniu_link);
                    wx.showToast({
                        title: '修改头像成功',
                        icon: 'success',
                    })
                } else {
                    // 提示图片有问题
                    wx.hideLoading();
                    if (data['errmsg'] == 'risky') {
                        wx.showToast({
                            title: '微信内容安全接口认为您上传的图片含有违法违规内容, 修改头像失败',
                            icon: 'none',
                        })
                    } else {
                        wx.showToast({
                            title: data['errmsg'],
                            icon: 'none',
                        })
                    }
                }
            }).catch(e => {
                console.log(e);
                wx.showToast({
                    title: '出错了，请稍后再试',
                    icon: 'none',
                })
            })
        }, (error) => {
            wx.hideLoading();
            wx.showToast({
                title: '上传头像文件失败',
                icon: 'none',
            })
            console.log('error: ' + error);
        }, {
            region: 'SCN',
            domain: 'https://img.wittcism.com',
            uptokenURL: 'https://wittcism.com/backend/api/v1/upload_token_for_wechat',
        }, (progress) => {})
    },
})

wittcism.imgSecCheckByURL 做的事情纯粹是把七牛 URL 传给后端

七牛图片 URL 比如：
https://img.wittcism.com/tmp/wx3e98618e26700e1b.o6zAJs6rSSMeG3ZYAlQjcxSTQuz0.BhMwMs4CuyEYec61c87a1767c8e5877e396fdc30a19b.jpg

我这里发的后端地址类似这样：https://example.com/api/v1/miniapp/img_sec_check_url
（仅供参考）

qiniuUploader.upload 纯粹只是上传图片到七牛

博客：http://1c7.me/2018-11-4-wechat-mini-app-imgseccheck-demo/

后端代码：Ruby on Rails 5.2

class Api::V1::MiniappController < Api::V1::ApplicationController
  # 接收图片地址
  # 从图片地址下载图片，并传给微信内容安全接口，原样返回结果
  def img_sec_check_url
    url = params[:url]
    unless url
      render json: {status: 2, message: '需要图片的 URL'}
      return
    end
    download = open(url)
    file_path = "/tmp/#{download.base_uri.to_s.split('/')[-1]}"
    file = IO.copy_stream(download, file_path)

    access_token = return_miniapp_access_token()
    url = "https://api.weixin.qq.com/wxa/img_sec_check?access_token=#{access_token}"
    r = RestClient::Request.execute(
      method: :post, 
      url: url, 
      :payload => {
        :multipart => true,
        :file => File.new(file_path, 'rb')
      }
    )
    r = JSON.parse(r)
    render json: r
    return
  end

  # 返回 access_token (用了 redis 做缓存)
  def return_miniapp_access_token
    redis = $redis

    if redis.get("wechat_miniapp_access_token")
      return redis.get("wechat_miniapp_access_token")
    end
    # if not exist in redis
    # now we have to send http request to get a access_token from weixin
    appid = Setting.wechat_mini_program_app_id
    appsecret = Setting.wechat_mini_program_app_secret

    url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=#{appid}&secret=#{appsecret}"
    r = RestClient::Request.execute({method: :get, url: url})
    r = JSON.parse(r)
    unless r['access_token']
      return false
    end
    redis.set("wechat_miniapp_access_token", r['access_token'])
    redis.expire("wechat_miniapp_access_token", r['expires_in'].to_i - 60) # 提早 60 秒过期
    return r['access_token']
  end

end