有時候，有人給我的網站留了言，但是我必須要開啟我的網站（https://www.xiandanplay.com/）才知道，所以我便決定給網站增加一個郵件推送的功能，好讓我第一時間知道。於是乎，按照我自己的思路，同時為了去學習瞭解rabbitmq以及EventBus概念，我便設計了一套郵件推送的功能，這裡分享出來，可能方案不是很好，大家不喜勿噴。
什麼是事件匯流排
事件匯流排是對釋出-訂閱模式的一種實現。它是一種集中式事件處理機制，允許不同的元件之間進行彼此通訊而又不需要相互依賴，達到一種解耦的目的。
關於這個概念，網上有很多講解的，這裡我推薦一個講的比較好的（事件匯流排知多少）
什麼是RabbitMQ
RabbitMQ這個就不用說了，想必到家都知道。
粗糙流程圖
簡單來解釋就是：
1、定義一個事件抽象類
public abstract class EventData
{
/// <summary>
/// 唯一標識
/// </summary>
public string Unique { get; set; }
/// <summary>
/// 是否成功
/// </summary>
public bool Success { get; set; }
/// <summary>
/// 結果
/// </summary>
public string Result { get; set; }
}
2、定義一個事件處理抽象類，以及對應的一個佇列訊息執行的一個記錄
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>
/// 開始處理
/// </summary>
/// <param name="unique"></param>
/// <returns></returns>
protected abstract Task BeginHandler(string unique);
/// <summary>
/// 處理中
/// </summary>
/// <param name="eventData"></param>
/// <returns></returns>
protected abstract Task<T> ProcessingHandler(T eventData);
/// <summary>
/// 處理完成
/// </summary>
/// <param name="eventData"></param>
/// <returns></returns>
protected abstract Task FinishHandler(T eventData);
}
[Table("Sys_TaskRecord")]
public class TaskRecord : Entity<long>
{
/// <summary>
/// 任務型別
/// </summary>
public TaskRecordType TaskType { get; set; }
/// <summary>
/// 任務狀態
/// </summary>
public int TaskStatu { get; set; }
/// <summary>
/// 任務值
/// </summary>
public string TaskValue { get; set; }
/// <summary>
/// 任務結果
/// </summary>
public string TaskResult { get; set; }
/// <summary>
/// 任務開始時間
/// </summary>
public DateTime TaskStartTime { get; set; }
/// <summary>
/// 任務完成時間
/// </summary>
public DateTime? TaskFinishTime { get; set; }
/// <summary>
/// 任務最後更新時間
/// </summary>
public DateTime? LastUpdateTime { get; set; }
/// <summary>
/// 任務名稱
/// </summary>
public string TaskName { get; set; }
/// <summary>
/// 附加資料
/// </summary>
public string AdditionalData { get; set; }
}
3、定義一個郵件事件訊息類，繼承自EventData，以及一個郵件處理的Hanler繼承自EventHandler
public class EmailEventData:EventData
{
/// <summary>
/// 郵件內容
/// </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, "[閒蛋]收到一條留言");
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、接著就是如何把事件訊息和事件Hanler關聯起來，那麼我這裡思路就是把EmailEventData的型別和CreateEmailHandler的型別先註冊到字典裡面，這樣我就可以根據EmailEventData找到對應的處理程式了，找型別還不夠，如何建立例項呢，這裡就還需要把CreateEmailHandler註冊到DI容器裡面，這樣就可以根據容器獲取物件了，如下
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不存在類名{0}的key", eventName));
return eventTypes[eventName];
}
------------------------------------------------------------------------------------------------------------------------------------------------------------
public object FindHandlerType(Type eventDataType)
{
if (!eventhandlers.ContainsKey(eventDataType))
throw new ArgumentException(string.Format("eventhandlers不存在型別{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、傳送訊息，這裡程式碼簡單，就是簡單的傳送訊息，這裡用eventData.GetType().Name作為訊息的RoutingKey，這樣消費這就可以根據這個key呼叫FindEventType，然後找到對應的處理程式了
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、訂閱訊息，核心的是這一段
Type eventType = _eventBusManager.FindEventType(eventName);
var eventData = (T)JsonConvert.DeserializeObject(body, eventType);
EventHandler<T> eventHandler = _eventBusManager.FindHandlerType(eventType) as EventHandler<T>;
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，這裡我使用的時候有個小坑，就是最開始是用using包裹這個IModel channel = connection.CreateModel();導致最後程式啟動後無法收到訊息，然後去rabbitmq的管理介面發現沒有channel連線，佇列也沒有消費者，最後發現可能是using執行完後就釋放掉了，把using去掉就好了。
好了，到此，我的思路大概講完了，現在我的網站留言也可以收到郵件了，那麼多測試郵件，哈哈哈哈哈
大家感興趣的話可以去我的網站（https://www.xiandanplay.com/）踩一踩，互加友鏈也可以的，謝謝大家，不喜勿噴嘍！