nopCommerce 3.9 大波浪系列 之 事件机制（生产者、消费者）

1 using System;
2 using System.Linq;
3 using Nop.Core.Infrastructure;
4 using Nop.Core.Plugins;
5 using Nop.Services.Logging;
6 
7 namespace Nop.Services.Events
8 {
9     /// <summary>
10     /// Evnt publisher
11     /// </summary>
12     public class EventPublisher : IEventPublisher
13     {
14         private readonly ISubscriptionService _subscriptionService;
15 
16         /// <summary>
17         /// Ctor
18         /// </summary>
19         /// <param name="subscriptionService"></param>
20         public EventPublisher(ISubscriptionService subscriptionService)
21         {
22             _subscriptionService = subscriptionService;
23         }
24 
25         /// <summary>
26         /// Publish to cunsumer
27         /// </summary>
28         /// <typeparam name="T">Type</typeparam>
29         /// <param name="x">Event consumer</param>
30         /// <param name="eventMessage">Event message</param>
31         protected virtual void PublishToConsumer<T>(IConsumer<T> x, T eventMessage)
32         {
33             //Ignore not installed plugins
34             var plugin = FindPlugin(x.GetType());
35             if (plugin != null && !plugin.Installed)
36                 return;
37 
38             try
39             {
40                 //消费者处理方法
41                 x.HandleEvent(eventMessage);
42             }
43             catch (Exception exc)
44             {
45                 //log error
46                 var logger = EngineContext.Current.Resolve<ILogger>();
47                 //we put in to nested try-catch to prevent possible cyclic (if some error occurs)
48                 try
49                 {
50                     logger.Error(exc.Message, exc);
51                 }
52                 catch (Exception)
53                 {
54                     //do nothing
55                 }
56             }
57         }
58 
59         /// <summary>
60         /// Find a plugin descriptor by some type which is located into its assembly
61         /// </summary>
62         /// <param name="providerType">Provider type</param>
63         /// <returns>Plugin descriptor</returns>
64         protected virtual PluginDescriptor FindPlugin(Type providerType)
65         {
66             if (providerType == null)
67                 throw new ArgumentNullException("providerType");
68 
69             if (PluginManager.ReferencedPlugins == null)
70                 return null;
71 
72             foreach (var plugin in PluginManager.ReferencedPlugins)
73             {
74                 if (plugin.ReferencedAssembly == null)
75                     continue;
76 
77                 if (plugin.ReferencedAssembly.FullName == providerType.Assembly.FullName)
78                     return plugin;
79             }
80 
81             return null;
82         }
83 
84         /// <summary>
85         /// 发送事件
86         /// </summary>
87         /// <typeparam name="T">Type</typeparam>
88         /// <param name="eventMessage">Event message</param>
89         public virtual void Publish<T>(T eventMessage)
90         {
91             var subscriptions = _subscriptionService.GetSubscriptions<T>();//获取订阅消费者
92             subscriptions.ToList().ForEach(x => PublishToConsumer(x, eventMessage));
93         }
94 
95     }
96 }
97