创建微信开放平台账号，然后创建网页应用

获取appid和appsecret

前端使用的vue，安装插件vue-wxlogin

调用代码

<wxlogin :appid="appId" :scope="scope" :redirect_uri="redirect_uri"></wxlogin>
<script>
import wxlogin from "vue-wxlogin";

const appId = ref("wx开头的appid");
const scope = ref("snsapi_login");
const redirect_uri = ref("跳转的URL，需要URL编码");//比如原来是http://www.baidu.com需要填写http%3A%2F%2Fwww.baidu.com,使用encodeURIComponent即可实现
</script>

这样就能出来二维码了，微信扫码之后有一个codehttps://www.xxxx.com/?code=011UQe100NJMTR1tsG100BNvo93UQe1n&state=
前端需要返回code给后台，后台解析
安装Nuget包https://github.com/fudiwei/DotNetCore.SKIT.FlurlHttpClient.Wechat


实现解密code，需要读取appid和appsecret，这两个参数都放到appsettings.json中

 "OpenWeixin": {
   "OpenWechatAppId": "",
   "OpenWechatAppSecret": ""
 }

OpenWeixinOptions

services.AddConfigurableOptions<OpenWeixinOptions>();

public class OpenWeixinOptions : IConfigurableOptions
{
    /// <summary>
    /// 微信开放平台appid
    /// </summary>
    public string OpenWechatAppId { get; set; }

    /// <summary>
    /// 微信开放平台appsecret
    /// </summary>
    public string OpenWechatAppSecret { get; set; }
}

编写帮助类OpenWechatHelper

using Furion;
using Furion.DependencyInjection;
using SKIT.FlurlHttpClient.Wechat.Api;
using SKIT.FlurlHttpClient.Wechat.Api.Models;

/// <summary>
/// 微信开放平台帮助类
/// </summary>
public class OpenWechatHelper : ISingleton
{
    private WechatApiClient client;

    /// <summary>
    /// 构造函数注入
    /// </summary>
    public OpenWechatHelper()
    {
        var wechatConfig = App.GetOptions<OpenWeixinOptions>();
        var options = new WechatApiClientOptions()
        {
            AppId = wechatConfig.OpenWechatAppId,
            AppSecret = wechatConfig.OpenWechatAppSecret,
        };
        client = new WechatApiClient(options);
    }

    /// <summary>
    /// 根据code获取某个应用下的微信用户id
    /// </summary>
    /// <param name="code"></param>
    /// <returns></returns>
    public async Task<string> GetOpenId(string code)
    {
        var request = new SnsOAuth2AccessTokenRequest();
        request.Code = code;
        var tokenResponse = await client.ExecuteSnsOAuth2AccessTokenAsync(request);
        if (!tokenResponse.IsSuccessful())
        {
            return string.Empty;
        }

        return tokenResponse.OpenId;
    }
}

剩下的按照业务逻辑处理即可