.NET：在ASPX、ASHX和MVC中使用IOC容器（菜鸟必看）

前言

程序开发的一个良好原则就是：“将使用和创建分开”。5年前有多少人采用这种风格呢？几乎没有。在IOC流行甚至泛滥的今天，还有一些团队没有使用IOC容器，有些是由于历史原因，有些是由于团队的文化。没有采用IOC的团队，找个机会拥抱一下吧。

我一直在用IOC容器，在此介绍一下如何将IOC集成到WebForm和WebMvc的应用系统中。

自动注入到ASPX和ASHX

框架支持

 1 using System;

 2 using System.Collections.Generic;

 3 using System.Linq;

 4 using System.Text;

 5 using System.Threading.Tasks;

 6 

 7 namespace Happy.Web

 8 {

 9     public interface IWantAutoDependInjection

10     {

11     }

12 }

 1 using System;

 2 using System.Collections.Generic;

 3 using System.Linq;

 4 using System.Text;

 5 using System.Threading.Tasks;

 6 

 7 namespace Happy.Web

 8 {

 9     [AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]

10     public sealed class DependToAttribute : Attribute

11     {

12         public Type DependToType { get; set; }

13 

14         public string Key { get; set; }

15     }

16 }

 1 using System;

 2 using System.Collections.Generic;

 3 using System.Linq;

 4 using System.Text;

 5 using System.Threading.Tasks;

 6 

 7 using System.Web;

 8 

 9 using Microsoft.Practices.ServiceLocation;

10 

11 using Happy.ExtensionMethods.Reflection;

12 

13 namespace Happy.Web

14 {

15     public class DependInjectionModule : IHttpModule

16     {

17         public void Init(HttpApplication context)

18         {

19             context.PreRequestHandlerExecute += OnPreRequestHandlerExecute;

20         }

21 

22         private void OnPreRequestHandlerExecute(object sender, EventArgs e)

23         {

24             if (!(HttpContext.Current.CurrentHandler is IWantAutoDependInjection))

25             {

26                 return;

27             }

28 

29             var properties = HttpContext.Current.CurrentHandler.GetType().GetProperties();

30 

31             foreach (var property in properties)

32             {

33                 var dependToAttribute = property.GetAttribute<DependToAttribute>(false);

34 

35                 if (dependToAttribute == null)

36                 {

37                     continue;

38                 }

39 

40                 var dependType = dependToAttribute.DependToType ?? property.PropertyType;

41 

42                 var value = ServiceLocator.Current.GetInstance(dependType, dependToAttribute.Key ?? string.Empty);

43 

44                 property.SetValue(HttpContext.Current.Handler, value);

45             }

46         }

47 

48         public void Dispose()

49         {

50         }

51     }

52 }

代码示例

 1 <configuration>

 2   <system.web>

 3     <compilation debug="true" targetFramework="4.5" />

 4     <httpRuntime targetFramework="4.5" />

 5   </system.web>

 6 

 7   <system.webServer>

 8     <modules>

 9       <add name="DependInjectionModule" type="Happy.Web.DependInjectionModule"/>

10     </modules>

11   </system.webServer>

12 

13 </configuration>

 1 using System;

 2 using System.Collections.Generic;

 3 using System.Linq;

 4 using System.Web;

 5 using System.Web.UI;

 6 using System.Web.UI.WebControls;

 7 

 8 using Happy.Web;

 9 

10 namespace WebStudy

11 {

12     public partial class Test : System.Web.UI.Page, IWantAutoDependInjection

13     {

14         [DependTo]

15         public ApplicationService ApplicationService { get; set; }

16 

17         protected void Page_Load(object sender, EventArgs e)

18         {

19             this.Response.Write(this.ApplicationService.GetMessage());

20         }

21     }

22 

23     public sealed class ApplicationService

24     {

25         public string GetMessage()

26         {

27             return "段光伟";

28         }

29     }

30 }

运行结果

 

自动注入到MVC

框架支持（最新版本）

 1 using System;

 2 using System.Collections.Generic;

 3 using System.Linq;

 4 using System.Text;

 5 using System.Threading.Tasks;

 6 

 7 using System.Web.Routing;

 8 using System.Web.Mvc;

 9 

10 using Microsoft.Practices.ServiceLocation;

11 

12 using Happy.DesignByContract;

13 

14 namespace Happy.Web.Mvc

15 {

16     public sealed class ServiceLocationDependencyResolver : IDependencyResolver

17     {

18         private readonly IServiceLocator _serviceLocator;

19 

20         public ServiceLocationDependencyResolver(IServiceLocator serviceLocator)

21         {

22             Check.RequireNotNull(serviceLocator, "serviceLocator");

23 

24             _serviceLocator = serviceLocator;

25         }

26 

27         public object GetService(Type serviceType)

28         {

29             Check.RequireNotNull(serviceType, "serviceType");

30 

31             try

32             {

33                 return _serviceLocator.GetInstance(serviceType);

34             }

35             catch

36             {

37                 return null;

38             }

39         }

40 

41         public IEnumerable<object> GetServices(Type serviceType)

42         {

43             Check.RequireNotNull(serviceType, "serviceType");

44 

45             try

46             {

47                 return _serviceLocator.GetAllInstances(serviceType);

48             }

49             catch

50             {

51                 return new List<object>();

52             }

53         }

54     }

55 }

代码示例

此处省略代码示例，有兴趣的朋友请留言交流。

备注

想象一下，开发人员只需要定义和声明，不需要手工组装（new）会有多爽。IOC容器的配置最好根据约定自动配置。