[翻译]自托管WebApi使用OWIN和Unity

Posted 2020-10-04

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OWIN托管的WebApi应用程序使用Unity,要比标准的WebApi应用程序使用Unity复杂一点点.

这篇博客展示怎样把ASP.NET Web API寄宿到一个控制台应用程序,使用OWIN自托管WebApi框架和Unity的Ioc.

需要实现下面的步骤:

　　1.把OWIN.Hosting和Unity的程序集添加到解决方案.

　　2.Unity的registrations和startup逻辑是必须的.

　　3.Unity的解析器需要添加到OWIN startup 的上下文.

　　4.释放资源的逻辑必须实现.

使用下面的nuget包,添加OWIN.Hosting:

http://www.nuget.org/packages/Microsoft.AspNet.WebApi.OwinSelfHost/

Install-Package Microsoft.AspNet.WebApi.OwinSelfHost -Pre

使用nuget管理器添加Unity(注意不是Unity.WebApi,下面有解释)

技术分享

一个能被Console应用程序或Windows Service调用的开始方法是必须要具备的.这个方法决定了使用Unity创建实例.这个方法也定义了服务的url和使用OWIN配置方法开始这个服务.

 1 using Owin; 
 2 using System.Web.Http;
 3 using Microsoft.Owin.Hosting;
 4 using System;
 5 using System.Net.Http;
 6 using Microsoft.Practices.Unity;
 7  
 8 namespace SelfHostWebApiOwin
 9 {
10     public class Startup
11     {
12         private static readonly IUnityContainer _container = UnityHelpers.GetConfiguredContainer();
13  
14         public static void StartServer()
15         {
16             string baseAddress = "http://localhost:8081/";
17             var startup = _container.Resolve<Startup>();
18             IDisposable webApplication = WebApp.Start(baseAddress, startup.Configuration);
19  
20             try
21             {
22                 Console.WriteLine("Started...");
23  
24                 Console.ReadKey();
25             }
26             finally
27             {
28                 webApplication.Dispose();
29             }
30         }        
31     }
32 }

Configuration(IAppBuilder appBuilder)提供我们服务所有必须的信息.这里可以添加authorization, filters, http logging,和其他的OWIN客户端

 1 public void Configuration(IAppBuilder appBuilder) 
 2 { 
 3   // Configure Web API for self-host. 
 4   HttpConfiguration config = new HttpConfiguration();
 5   config.DependencyResolver = new UnityDependencyResolver(
 6       SelfHostWebApiOwin.UnityHelpers.GetConfiguredContainer());
 7  
 8   config.Routes.MapHttpRoute( 
 9                 name: "DefaultApi", 
10                 routeTemplate: "api/{controller}/{id}", 
11                 defaults: new { id = RouteParameter.Optional } 
12             ); 
13  
14   appBuilder.UseWebApi(config); 
15 }

在这个方法里,HttpConfiguration.DependencyResolver设置了一个UnityDependencyResolver实例.WebApi controllers使用构造函数注入必须要这么做.UnityDependencyResolver类完全相当于Unity.WebApi.UnityDependencyResolver类,我们不使用Unity.WebApi,因为这是一个自托管的OWIN应用程序.

http://unity.codeplex.com/SourceControl/latest#Unity/Unity.WebApi/Src/UnityDependencyResolver.cs

UnityDependencyResolver : IDependencyResolver

Unity的注册必须被定义.他被定义在了UnityHelper类.按照注册惯例注册实例.属性用来使用每个接口,类的生命周期注册类型可以更舒适的被定义,没有必要配置地狱.

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Reflection;
 4 using Microsoft.Practices.Unity;
 5 using System.Linq;
 6 using SelfHostWebApiOwin.Business.Attributes;
 7 using SelfHostWebApiOwin;
 8  
 9 namespace SelfHostWebApiOwin
10 {
11     public static class UnityHelpers
12     {
13         #region Unity Container
14         private static Lazy<IUnityContainer> container = new Lazy<IUnityContainer>(() =>
15         {
16             var container = new UnityContainer();
17             RegisterTypes(container);
18             return container;
19         });
20  
21         public static IUnityContainer GetConfiguredContainer()
22         {
23             return container.Value;
24         }
25         #endregion
26  
27         //private static readonly Type[] EmptyTypes = new Type[0];
28  
29         public static IEnumerable<Type> GetTypesWithCustomAttribute<T>( Assembly[] assemblies)
30         {
31             foreach (var assembly in assemblies)
32             {
33                 foreach (Type type in assembly.GetTypes())
34                 {
35                     if (type.GetCustomAttributes(typeof(T), true).Length > 0)
36                     {
37                         yield return type;
38                     }
39                 }
40             }
41         }
42  
43         public static void RegisterTypes(IUnityContainer container)
44         {
45             var myAssemblies = AppDomain.CurrentDomain.GetAssemblies().Where(a => a.FullName.StartsWith("SelfHostWebApiOwin")).ToArray();
46  
47             container.RegisterType(typeof(Startup));
48  
49             container.RegisterTypes(
50                 UnityHelpers.GetTypesWithCustomAttribute<UnityIoCContainerControlledAttribute>(myAssemblies),
51                 WithMappings.FromMatchingInterface,
52                 WithName.Default,
53                 WithLifetime.ContainerControlled,
54                 null
55                 ).RegisterTypes(
56                          UnityHelpers.GetTypesWithCustomAttribute<UnityIoCTransientLifetimeAttribute>(myAssemblies),
57                          WithMappings.FromMatchingInterface,
58                          WithName.Default,
59                          WithLifetime.Transient);
60  
61         }
62  
63     }
64 }

这有一个attribute的小例子.

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Web;
 5  
 6 namespace SelfHostWebApiOwin.Business.Attributes
 7 {
 8     [System.AttributeUsage(System.AttributeTargets.Class | System.AttributeTargets.Struct)]
 9     public class UnityIoCTransientLifetimeAttribute : System.Attribute
10     {
11         public double version;
12  
13         public UnityIoCTransientLifetimeAttribute()
14         {
15             version = 1.0;
16         }
17     }
18 }

现在可以创建业务逻辑层.在这层我只使用构造函数注入.这些类是松耦合的并且容易被测试.

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Web;
 5 using SelfHostWebApiOwin.Business.Logging;
 6 using SelfHostWebApiOwin.Business.Attributes;
 7  
 8 namespace SelfHostWebApiOwin.Business
 9 {
10     [UnityIoCTransientLifetimeAttribute]
11     public class BusinessClass : IBusinessClass
12     {
13         private IUnitOfWorkExample _unitOfWorkExample;
14  
15         public BusinessClass(IUnitOfWorkExample unitOfWorkExample)
16         {
17             _unitOfWorkExample = unitOfWorkExample;
18             UnityEventLogger.Log.CreateUnityMessage("BusinessClass");
19         }
20  
21         private bool _disposed = false;
22  
23         public string Hello()
24         {
25             return _unitOfWorkExample.HelloFromUnitOfWorkExample();
26         }
27  
28         public void Dispose()
29         {
30             _unitOfWorkExample.Dispose();
31             UnityEventLogger.Log.DisposeUnityMessage("BusinessClass");
32             if (!_disposed)
33             {
34                 _disposed = true;
35             }
36         }
37     }
38 }

现在这些类可以使用构造函数注入到Controllers.

1 public class ValuesController : ApiController
2     {
3         private readonly IBusinessClass _businessClass;
4         private readonly IBusinessClass2 _businessClass2;
5         public ValuesController(IBusinessClass businessClass, IBusinessClass2 businessClass2)
6         {
7             _businessClass = businessClass;
8             _businessClass2 = businessClass2;
9         }