基于事件总线EventBus实现邮件推送功能
有时候,有人给我的网站留了言,但是我必须要打开我的网站(https://www.xiandanplay.com/)才知道,所以我便决定给网站增加一个邮件推送的功能,好让我第一时间知道。于是乎,按照我自己的思路,同时为了去学习了解rabbitmq以及EventBus概念,我便设计了一套邮件推送的功能,这里分享出来,可能方案不是很好,大家不喜勿喷。
什么是事件总线
事件总线是对发布-订阅模式的一种实现。它是一种集中式事件处理机制,允许不同的组件之间进行彼此通信而又不需要相互依赖,达到一种解耦的目的。
关于这个概念,网上有很多讲解的,这里我推荐一个讲的比较好的(事件总线知多少)
什么是RabbitMQ
RabbitMQ这个就不用说了,想必到家都知道。
粗糙流程图
简单来解释就是:
1、定义一个事件抽象类
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | public abstract class EventData { /// <summary> /// 唯一标识 /// </summary> public string Unique { get ; set ; } /// <summary> /// 是否成功 /// </summary> public bool Success { get ; set ; } /// <summary> /// 结果 /// </summary> public string Result { get ; set ; } } |
2、定义一个事件处理抽象类,以及对应的一个队列消息执行的一个记录
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 | public abstract class EventHandler<T> where T : EventData { public async Task Handler(T eventData) { await BeginHandler(eventData.Unique); eventData = await ProcessingHandler(eventData); if (eventData.Success) await FinishHandler(eventData); } /// <summary> /// 开始处理 /// </summary> /// <param name="unique"></param> /// <returns></returns> protected abstract Task BeginHandler( string unique); /// <summary> /// 处理中 /// </summary> /// <param name="eventData"></param> /// <returns></returns> protected abstract Task<T> ProcessingHandler(T eventData); /// <summary> /// 处理完成 /// </summary> /// <param name="eventData"></param> /// <returns></returns> protected abstract Task FinishHandler(T eventData); } [Table( "Sys_TaskRecord" )] public class TaskRecord : Entity< long > { /// <summary> /// 任务类型 /// </summary> public TaskRecordType TaskType { get ; set ; } /// <summary> /// 任务状态 /// </summary> public int TaskStatu { get ; set ; } /// <summary> /// 任务值 /// </summary> public string TaskValue { get ; set ; } /// <summary> /// 任务结果 /// </summary> public string TaskResult { get ; set ; } /// <summary> /// 任务开始时间 /// </summary> public DateTime TaskStartTime { get ; set ; } /// <summary> /// 任务完成时间 /// </summary> public DateTime? TaskFinishTime { get ; set ; } /// <summary> /// 任务最后更新时间 /// </summary> public DateTime? LastUpdateTime { get ; set ; } /// <summary> /// 任务名称 /// </summary> public string TaskName { get ; set ; } /// <summary> /// 附加数据 /// </summary> public string AdditionalData { get ; set ; } } |
3、定义一个邮件事件消息类,继承自EventData,以及一个邮件处理的Hanler继承自EventHandler
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 | public class EmailEventData:EventData { /// <summary> /// 邮件内容 /// </summary> public string Body { get ; set ; } /// <summary> /// 接收者 /// </summary> public string Reciver { get ; set ; } } public class CreateEmailHandler<T> : Core.EventBus.EventHandler<T> where T : EventData { private IEmailService emailService; private IUnitOfWork unitOfWork; private ITaskRecordService taskRecordService; public CreateEmailHandler(IEmailService emailService, IUnitOfWork unitOfWork, ITaskRecordService taskRecordService) { this .emailService = emailService; this .unitOfWork = unitOfWork; this .taskRecordService = taskRecordService; } protected override async Task BeginHandler( string unique) { await taskRecordService.UpdateRecordStatu(Convert.ToInt64(unique), ( int )MqMessageStatu.Processing); await unitOfWork.CommitAsync(); } protected override async Task<T> ProcessingHandler(T eventData) { try { EmailEventData emailEventData = eventData as EmailEventData; await emailService.SendEmail(emailEventData.Reciver, emailEventData.Reciver, emailEventData.Body, "[闲蛋]收到一条留言" ); eventData.Success = true ; } catch (Exception ex) { await taskRecordService.UpdateRecordFailStatu(Convert.ToInt64(eventData.Unique), ( int )MqMessageStatu.Fail,ex.Message); await unitOfWork.CommitAsync(); eventData.Success = false ; } return eventData; } protected override async Task FinishHandler(T eventData) { await taskRecordService.UpdateRecordSuccessStatu(Convert.ToInt64(eventData.Unique), ( int )MqMessageStatu.Finish, "" ); await unitOfWork.CommitAsync(); } |
4、接着就是如何把事件消息和事件Hanler关联起来,那么我这里思路就是把EmailEventData的类型和CreateEmailHandler的类型先注册到字典里面,这样我就可以根据EmailEventData找到对应的处理程序了,找类型还不够,如何创建实例呢,这里就还需要把CreateEmailHandler注册到DI容器里面,这样就可以根据容器获取对象了,如下
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | public void AddSub<T, TH>() where T : EventData where TH : EventHandler<T> { Type eventDataType = typeof (T); Type handlerType = typeof (TH); if (!eventhandlers.ContainsKey( typeof (T))) eventhandlers.TryAdd(eventDataType, handlerType); _serviceDescriptors.AddScoped(handlerType); } ------------------------------------------------------------------------------------------------------------------- public Type FindEventType( string eventName) { if (!eventTypes.ContainsKey(eventName)) throw new ArgumentException( string .Format( "eventTypes不存在类名{0}的key" , eventName)); return eventTypes[eventName]; } ------------------------------------------------------------------------------------------------------------------------------------------------------------ public object FindHandlerType(Type eventDataType) { if (!eventhandlers.ContainsKey(eventDataType)) throw new ArgumentException( string .Format( "eventhandlers不存在类型{0}的key" , eventDataType.FullName)); var obj = _buildServiceProvider(_serviceDescriptors).GetService(eventhandlers[eventDataType]); return obj; } ---------------------------------------------------------------------------------------------------------------------------------- private static IServiceCollection AddEventBusService( this IServiceCollection services) { string exchangeName = ConfigureProvider.configuration.GetSection( "EventBusOption:ExchangeName" ).Value; services.AddEventBus(Assembly.Load( "XianDan.Application" ).GetTypes()) .AddSubscribe<EmailEventData, CreateEmailHandler<EmailEventData>>(exchangeName, ExchangeType.Direct, BizKey.EmailQueueName); return services; } |
5、发送消息,这里代码简单,就是简单的发送消息,这里用eventData.GetType().Name作为消息的RoutingKey,这样消费这就可以根据这个key调用FindEventType,然后找到对应的处理程序了
1 2 3 4 5 6 7 8 9 | using (IModel channel = connection.CreateModel()) { string routeKey = eventData.GetType().Name; string message = JsonConvert.SerializeObject(eventData); byte [] body = Encoding.UTF8.GetBytes(message); channel.ExchangeDeclare(exchangeName, exchangeType, true , false , null ); channel.QueueDeclare(queueName, true , false , false , null ); channel.BasicPublish(exchangeName, routeKey, null , body); } |
6、订阅消息,核心的是这一段
Type eventType = _eventBusManager.FindEventType(eventName);
var eventData = (T)JsonConvert.DeserializeObject(body, eventType);
EventHandler<T> eventHandler = _eventBusManager.FindHandlerType(eventType) as EventHandler<T>;
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 | public void Subscribe<T, TH>( string exchangeName, string exchangeType, string queueName) where T : EventData where TH : EventHandler<T> { try { _eventBusManager.AddSub<T, TH>(); IModel channel = connection.CreateModel(); channel.QueueDeclare(queueName, true , false , false , null ); channel.ExchangeDeclare(exchangeName, exchangeType, true , false , null ); channel.QueueBind(queueName, exchangeName, typeof (T).Name, null ); var consumer = new EventingBasicConsumer(channel); consumer.Received += async (model, ea) => { string eventName = ea.RoutingKey; byte [] resp = ea.Body.ToArray(); string body = Encoding.UTF8.GetString(resp); try { Type eventType = _eventBusManager.FindEventType(eventName); var eventData = (T)JsonConvert.DeserializeObject(body, eventType); EventHandler<T> eventHandler = _eventBusManager.FindHandlerType(eventType) as EventHandler<T>; await eventHandler.Handler(eventData); } catch (Exception ex) { LogUtils.LogError(ex, "EventBusRabbitMQ" , ex.Message); } finally { channel.BasicAck(ea.DeliveryTag, false ); } }; channel.BasicConsume(queueName, autoAck: false , consumer: consumer); } catch (Exception ex) { LogUtils.LogError(ex, "EventBusRabbitMQ.Subscribe" , ex.Message); } } |
注意,这里我使用的时候有个小坑,就是最开始是用using包裹这个IModel channel = connection.CreateModel();导致最后程序启动后无法收到消息,然后去rabbitmq的管理界面发现没有channel连接,队列也没有消费者,最后发现可能是using执行完后就释放掉了,把using去掉就好了。
好了,到此,我的思路大概讲完了,现在我的网站留言也可以收到邮件了,那么多测试邮件,哈哈哈哈哈
大家感兴趣的话可以去我的网站(https://www.xiandanplay.com/)踩一踩,互加友链也可以的,谢谢大家,不喜勿喷喽!
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