Asp.Net Core微信服务中间件-.NetCore2.1

  又封周末，闲暇无聊，随手写了一个关于微信公众号服务的中间件，基于.NetCore2.1。服务类库采用.Net Standard2.0，兼容.net 4.6.1。

整体思路是，设计一个中间件，提供微信消息推送服务。目前实现了，接收微信消息推送后，根据消息类型，对事件消息和被动接收消息分别进行了处理。

在中间件和服务之间，创建一个服务提供类，拥有提供消息的处理逻辑，开发者，可以实现服务提供接口，完成自己的逻辑。下面，让我们看看关于中间件的代码设计：

这里，我新建了一个名为WeiXinMiddleware的类，代码如下：

    /// <summary>
    /// <![CDATA[微信中间件]]>
    /// </summary>
    public class WeiXinMiddleware
    {
        /// <summary>
        /// 
        /// </summary>
        private RequestDelegate Next = null;

        /// <summary>
        /// <![CDATA[配置]]>
        /// </summary>
        public IConfiguration Configuration { get; }


        /// <summary>
        /// <![CDATA[中间件配置信息]]>
        /// </summary>
        public OAuth.WeiXinServerOptions ServerOptions { get; set; }

        /// <summary>
        /// <![CDATA[构造]]>
        /// </summary>
        /// <param name="requestDelegate"></param>
        /// <param name="configuration"></param>
        public WeiXinMiddleware(RequestDelegate requestDelegate, IConfiguration configuration, OAuth.WeiXinServerOptions serverOptions)
        {
            Next = requestDelegate;
            Configuration = configuration;
            ServerOptions = serverOptions;
        }

        /// <summary>
        /// <![CDATA[调用]]>
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public async Task Invoke(HttpContext context)
        {if (context.Request.Path == ServerOptions.NotifyPath)
            {
                //微信服务
                if (ServerOptions.WeiXinServerProvider == null) ServerOptions.WeiXinServerProvider = (OAuth.IWeiXinServerProvider)context.RequestServices.GetService(typeof(OAuth.IWeiXinServerProvider));
                await ServerOptions.WeiXinServerProvider.Run(context, Configuration);
                return;
            }
            await Next.Invoke(context);
        }
    }

代码其实很简单，就是在类内部定义一个Invoke任务，再声明一个Next属性，用于请求的下一步处理委托。在中间件的构造函数中，进行了注入，其中有一个

WeiXinServerOptions 类，它便是定义中间件所需的配置信息，也是对外提供的接口，让我们看看具体的代码：

 /// <summary>
    /// 
    /// </summary>
    public class WeiXinServerOptions
    {
        /// <summary>
        ///<![CDATA[微信通知地址]]>
        /// </summary>
        public PathString NotifyPath { get; set; }

        /// <summary>
        /// 
        /// </summary>
        private IWeiXinServerProvider _ServerProvider = null;

        /// <summary>
        /// <![CDATA[微信服务提供程序]]>
        /// </summary>
        public IWeiXinServerProvider WeiXinServerProvider
        {
            get
            {
                return _ServerProvider;
            }
            set
            {
                _ServerProvider = value;
                _ServerProvider.ServerOptions = this;
            }
        }

        /// <summary>
        /// <![CDATA[当接收到消息时]]>
        /// </summary>
        public Func<HttpContext, Task> OnRecieveAsync { get; set; }

        /// <summary>
        /// <![CDATA[扫描事件]]>
        /// </summary>
        public Func<WeiXinContext, Task> OnScanAsync { get; set; }

        /// <summary>
        /// <![CDATA[关注事件]]>
        /// </summary>
        public Func<WeiXinContext, Task> OnSubscribeAsync { get; set; }

        /// <summary>
        /// <![CDATA[取消关注]]>
        /// </summary>
        public Func<WeiXinContext, Task> OnUnsubscribeAsync { get; set; }

        /// <summary>
        /// <![CDATA[菜单点击事件]]>
        /// </summary>
        public Func<WeiXinContext, Task> OnClickAsync { get; set; }

        /// <summary>
        /// <![CDATA[点击链接]]>
        /// </summary>
        public Func<WeiXinContext, Task> OnViewAsync { get; set; }

        /// <summary>
        /// <![CDATA[上报地理位置]]>
        /// </summary>
        public Func<WeiXinContext, Task> OnLocationAsync { get; set; }

        /// <summary>
        /// <![CDATA[被动接收普通消息]]>
        /// </summary>
        public Func<HttpContext, Task> OnRecieveMessageAsync { get; set; }
    }

这个类中，定义了中间件要拦截处理的URL，以及时间消息的处理委托，有了这些委托，我们就可以很灵活的实现在接收到微信推送消息后的逻辑处理。

这个类中，还定义了一个WeiXinServerProvider属性，它是接口IWeiXinServerProvider的派生，让我们看看它定义的成员吧！

    public interface IWeiXinServerProvider
    {

        /// <summary>
        /// 
        /// </summary>
        OAuth.WeiXinServerOptions ServerOptions { get; set; }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="context"></param>
        /// <param name="configuration"></param>
        /// <param name="serverOptions"></param>
        /// <returns></returns>
        Task Run(HttpContext context, IConfiguration configuration);
    }

很简单吧，一个属性，一个运行任务的函数。

上面几个类是我服务的核心，下面我又创建了2个扩展类，分别为添加中间件和IOC注入服务。

    /// <summary>
    /// <![CDATA[微信中间件扩展]]>
    /// </summary>
    public static class WeiXinMiddlewareExtensions
    {

        /// <summary>
        /// <![CDATA[]]>
        /// </summary>
        /// <param name="app"></param>
        /// <param name="serverOptions"></param>
        public static void UseWeiXinServer(this IApplicationBuilder app, OAuth.WeiXinServerOptions serverOptions)
        {
            app.UseMiddleware<Middleware.WeiXinMiddleware>(serverOptions);
        }
    }

下面是IOC注入的扩展方法：

    /// <summary>
    /// 
    /// </summary>
    public static class WeiXinServiceCollectionExtensions
    {
        /// <summary>
        /// 
        /// </summary>
        /// <param name="services"></param>
        public static void AddWeiXinServer(this IServiceCollection services)
        {
            services.AddSingleton(typeof(OAuth.IWeiXinServerProvider), typeof(OAuth.WeiXinServer));//单例：IOC注册服务类型
        }
    }

完成以上代码后，最后让我们再Start类中，进行服务的配置。

public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.Configure<CookiePolicyOptions>(options =>
            {
                // This lambda determines whether user consent for non-essential cookies is needed for a given request.
                options.CheckConsentNeeded = context => true;
                options.MinimumSameSitePolicy = SameSiteMode.None;
            });

            services.AddWeiXinServer();//IOC注册服务类型
            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="app"></param>
        /// <param name="env"></param>
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                app.UseHsts();
            }

            //使用微信中间件
            app.UseWeiXinServer(new OAuth.WeiXinServerOptions()
            {
                NotifyPath = new PathString("/OAuth/WeiXin"),
                //WeiXinServerProvider = new OAuth.WeiXinServer(),//此处也可也手动设置，默认通过IOC容器创建WeiXinServer实例。
                OnScanAsync = (context) => { return Task.Delay(0); },
                OnClickAsync = (context) => { return Task.Delay(0); },
                OnSubscribeAsync = (context) => { return Task.Delay(0); },
                OnUnsubscribeAsync = (context) => { return Task.Delay(0); },
                OnViewAsync = (context) => { return Task.Delay(0); },
                OnRecieveMessageAsync = (context) => { return Task.Delay(0); },
            });

            app.UseStaticFiles();
            app.UseCookiePolicy();
            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }

让我们再看看WeiXinServer类的定义：

  /// <summary>
    /// <![CDATA[微信服务]]>
    /// </summary>
    public class WeiXinServer : IWeiXinServerProvider
    {

        /// <summary>
        /// <![CDATA[服务选项]]>
        /// </summary>
        public OAuth.WeiXinServerOptions ServerOptions { get; set; }

        /// <summary>
        /// 
        /// </summary>
        public WeiXinServer()
        {

        }


        /// <summary>
        /// <![CDATA[运行服务]]>
        /// </summary>
        /// <param name="context"></param>
        /// <param name="configuration"></param>
        /// <param name="serverOptions"></param>
        /// <returns></returns>
        public async Task Run(HttpContext context, IConfiguration configuration)
        {
            #region 1、验证签名
            if (context.Request.Method.ToUpper() == "GET")
            {
                context.Response.ContentType = "text/plain;charset=utf-8";
                context.Response.StatusCode = 200;

                //1、验证签名
                if (WeiXin.Sdk.Common.Util.CheckSignature(context.Request.Query["nonce"],
                                                          context.Request.Query["timestamp"],
                                                          context.Request.Query["signature"],
                                                          configuration.GetSection("WeiXinOAuth")["Token"]))
                {
                    await context.Response.WriteAsync(context.Request.Query["echostr"]);
                    return;
                }
                await context.Response.WriteAsync("无效签名！");
                return;
            }
            #endregion  1、验证签名

            #region 2、接收微信消息
            await OnRecieve(context);//接收消息
            #endregion 2、接收微信消息
        }

        #region 虚方法
        /// <summary>
        /// <![CDATA[虚方法，接收消息后处理]]>
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public virtual Task OnRecieve(HttpContext context)
        {
            if (ServerOptions.OnRecieveAsync != null) return ServerOptions.OnRecieveAsync(context);
            string strRecieveBody = null;//接收消息
            using (System.IO.StreamReader streamReader = new System.IO.StreamReader(context.Request.Body))
            {
                strRecieveBody = streamReader.ReadToEndAsync().GetAwaiter().GetResult();
            }
            //序列化
            WeiXin.Sdk.Common.Serialization.XmlSerializer xmlSerializer = new WeiXin.Sdk.Common.Serialization.XmlSerializer(typeof(WeiXin.Sdk.Domain.Messages.Message));
            var recieve = (WeiXin.Sdk.Domain.Messages.Message)xmlSerializer.Deserialize(strRecieveBody);

            //事件消息
            if (recieve.MsgType == WeiXin.Sdk.Common.Constants.SystemConstants.MSG_TYPE.EVENT)
            {
                var weiXinContext = new WeiXinContext(recieve, context);

                 var weiXinContext = new WeiXinContext(recieve, context);
                 var actionName = recieve.Event.ToLower();
                 actionName = actionName.First().ToString().ToUpper() + actionName.Substring(1);
                 var action = this.GetType().GetMethod($"On{actionName}");
                 if (action != null) return (Task)action.Invoke(this, new object[] { weiXinContext });

            }
            //被动接收消息
            else
            {
                return OnRecieveMessage(context);
            }
            return Task.Delay(0);
        }


        /// <summary>
        /// <![CDATA[被动接收消息]]>
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public virtual Task OnRecieveMessage(HttpContext context)
        {
            if (ServerOptions.OnRecieveMessageAsync != null) return ServerOptions.OnRecieveMessageAsync(context);
            return Task.Delay(0);
        }


        /// <summary>
        /// <![CDATA[扫描事件]]>
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public virtual Task OnScan(WeiXinContext context)
        {
            if (ServerOptions.OnScanAsync != null) return ServerOptions.OnScanAsync(context);
            return Task.Delay(0);
        }

        /// <summary>
        /// <![CDATA[关注事件]]>
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public virtual Task OnSubscribe(WeiXinContext context)
        {
            if (ServerOptions.OnSubscribeAsync != null) return ServerOptions.OnSubscribeAsync(context);
            return Task.Delay(0);
        }

        /// <summary>
        /// <![CDATA[取消关注]]>
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public virtual Task OnUnsubscribe(WeiXinContext context)
        {
            if (ServerOptions.OnUnsubscribeAsync != null) return ServerOptions.OnUnsubscribeAsync(context);
            return Task.Delay(0);
        }

        /// <summary>
        ///  <![CDATA[菜单点击]]>
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public virtual Task OnClick(WeiXinContext context)
        {
            if (ServerOptions.OnClickAsync != null) return ServerOptions.OnClickAsync(context);
            return Task.Delay(0);
        }

        /// <summary>
        /// <![CDATA[点击菜单链接]]>
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public virtual Task OnView(WeiXinContext context)
        {
            if (ServerOptions.OnViewAsync != null) return ServerOptions.OnViewAsync(context);
            return Task.Delay(0);
        }

        /// <summary>
        /// <![CDATA[上报地理位置]]>
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public virtual Task OnLocation(WeiXinContext context)
        {
            if (ServerOptions.OnLocationAsync != null) return ServerOptions.OnLocationAsync(context);
            return Task.Delay(0);
        }
        #endregion
    }

WeiXinServer类中还定义了时间消息的相关的虚方法，虚方法中，调用Options配置中定义的委托，这样，开发者一方面可以通过继承WeiXinServer或IWeiXinServerProvider接口，或通过设置Options属性，来灵活运用，开发者可根据自身需求，完成

对应业务逻辑即可。有了这些设计，我们可以轻松配置和完成微信消息的处理。

以上内容的全部代码，可以通过访问https://gitee.com/lichaoqiang/weixinmd 获取，不足之处，还望不吝赐教。