Asp.net MVC源码分析 -- Filter 以及调用优先级

在Asp.net MVC 框架中一共有四种型的Filter,它们分别是

1.IActionFilter

2.IAuthorizationFilter

3.IExceptionFilter

4.IResultFilter

别外再加上一个GlobalFilters.Filters全局的,看起来挺多但是基本上这些Filter都与Action的调用有关,

让我沿着Mvc3.0源码一一找出它们的线索。

首先让我们看FilterProviders.cs，这是一个全局的系统默认FilterFilter provider,当然们也可以向里面加自定义的provider.

FilterProviders.cs

 1 namespace System.Web.Mvc {

 2     public static class FilterProviders {

 3         static FilterProviders() {

 4             Providers = new FilterProviderCollection();

 5             Providers.Add(GlobalFilters.Filters);

 6             Providers.Add(new FilterAttributeFilterProvider());

 7             Providers.Add(new ControllerInstanceFilterProvider());

 8         }

 9

10         public static FilterProviderCollection Providers {

11             get;

12             private set;

13         }

14     }

15 }

这里面最为重要的是FilterAttributeFilterProvider，它提供了找出Action所有在元数据中Filter的功能方法。

FilterAttributeFilterProvider.cs

 1   public class FilterAttributeFilterProvider : IFilterProvider {

 2         private readonly bool _cacheAttributeInstances;

 3

 4         public FilterAttributeFilterProvider()

 5             : this(true) {

 6         }

 7

 8         public FilterAttributeFilterProvider(bool cacheAttributeInstances) {

 9             _cacheAttributeInstances = cacheAttributeInstances;

10         }

11

12         protected virtual IEnumerable<FilterAttribute> GetActionAttributes(ControllerContext controllerContext, ActionDescriptor actionDescriptor) {

13             return actionDescriptor.GetFilterAttributes(_cacheAttributeInstances);

14         }

15

16         protected virtual IEnumerable<FilterAttribute> GetControllerAttributes(ControllerContext controllerContext, ActionDescriptor actionDescriptor) {

17             return actionDescriptor.ControllerDescriptor.GetFilterAttributes(_cacheAttributeInstances);

18         }

19

20         public virtual IEnumerable<Filter> GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor) {

21             ControllerBase controller = controllerContext.Controller;

22             if (c