一直都知道MVC中的ActionFilter,只是没有在实际项目中使用过。
顾名思义，ActionFilter就是指在Action上的Filter, 那么，在Action上的Filter到底有哪些呢。首先我们看看MVC中的Controller基类（抽象类）
public abstract class Controller : ControllerBase, IActionFilter, IAuthenticationFilter, IAuthorizationFilter, IDisposable, IExceptionFilter, IResultFilter, IAsyncController, IController, IAsyncManagerContainer
{
}
我们可以看到，它有5个Filter,分别是IActionFilter, IAuthenticationFilter, IAuthorizationFilter, IExceptionFilter, IResultFilter. 我们先看看第一个IActionFilter
IActionFilter解析
从名称就可以看出，IActionFilter是一个接口.源码如下
//
// 摘要:
// Defines the methods that are used in an action filter.
public interface IActionFilter
{
//
// 摘要:
// Called after the action method executes.
//
// 参数:
// filterContext:
// The filter context.
void OnActionExecuted(ActionExecutedContext filterContext);
//
// 摘要:
// Called before an action method executes.
//
// 参数:
// filterContext:
// The filter context.
void OnActionExecuting(ActionExecutingContext filterContext);
}
可以看到，该接口中有两个方法，一个是OnActionExecuted (执行完Action之后执行该方法)，另一个是OnActionExecuting(执行Action之前执行该方法)
也就是这两个方法分别在Action的前后执行. 所以它可以用于记录日志，获取action的访问量......
知道了之后，那么我们如何来实现ActionFilter呢。
我们注意到，Controller基类继承了IActionFilter接口，而我们在MVC中写的Controller又都继承自Controller基类, 所以我们应该可以直接在MVC的Controller中override这两个方法
1. 用override的方式来实现ActionFilter
public class HomeController : Controller
{
public ActionResult Index()
{
return View();
} protected override void OnActionExecuting(ActionExecutingContext filterContext)
{
filterContext.HttpContext.Response.Write("Execute something before action"); base.OnActionExecuting(filterContext);
} protected override void OnActionExecuted(ActionExecutedContext filterContext)
{
filterContext.HttpContext.Response.Write("Execute something after action"); base.OnActionExecuted(filterContext);
}
}
这样好像就可以的，但是它有个问题，就是它只能用于HomeController, 有没有一种方法，我能写一个ActionFilter,可以用于多个Controller中的不同Action呢
显然，可以做到。我们可以自己写一个ActionFilter的类，使它继承IActionFilter, 如下：
2. 自定义一个ActionFilter 属性来实现IActionFilter接口
public class MyActionFilterAttribute : Attribute, IActionFilter
{
public void OnActionExecuted(ActionExecutedContext filterContext)
{
filterContext.HttpContext.Response.Write("Execute something before action");
} public void OnActionExecuting(ActionExecutingContext filterContext)
{
filterContext.HttpContext.Response.Write("Execute something after action");
}
}
好了，到现在我们就有自己写的ActionFilter了，叫做“MyActionFilter”, 如何使用它呢，很简单的
public class HomeController : Controller
{
[MyActionFilter]
public ActionResult Index()
{
return View();
}
}
除了上面两种方法，还有没有其他方法呢。事实上是有的,MVC Framework自己给我们提供了一个ActionFilterAttribute特性，这也是一个抽象类，我们来看看源码
//
// 摘要:
// Represents the base class for filter attributes.
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = false)]
public abstract class ActionFilterAttribute : FilterAttribute, IActionFilter, IResultFilter
{
//
// 摘要:
// Initializes a new instance of the System.Web.Mvc.ActionFilterAttribute class.
protected ActionFilterAttribute(); //
// 摘要:
// Called by the ASP.NET MVC framework after the action method executes.
//
// 参数:
// filterContext:
// The filter context.
public virtual void OnActionExecuted(ActionExecutedContext filterContext);
//
// 摘要:
// Called by the ASP.NET MVC framework before the action method executes.
//
// 参数:
// filterContext:
// The filter context.
public virtual void OnActionExecuting(ActionExecutingContext filterContext);
//
// 摘要:
// Called by the ASP.NET MVC framework after the action result executes.
//
// 参数:
// filterContext:
// The filter context.
public virtual void OnResultExecuted(ResultExecutedContext filterContext);
//
// 摘要:
// Called by the ASP.NET MVC framework before the action result executes.
//
// 参数:
// filterContext:
// The filter context.
public virtual void OnResultExecuting(ResultExecutingContext filterContext);
}
所以，我们可以写一个自己的ActionFilter属性，来实现MVC Framework提供的这个类ActionFilterAttribute就好
3. 自定义一个ActionFilter 类来继承ActionFilterAttribute类
namespace MyApplication.Controllers
{
public class HomeController : Controller
{
[MyActionFilter]
public ActionResult Index()
{
return View();
}
} public class MyActionFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
base.OnActionExecuting(filterContext);
} public override void OnActionExecuted(ActionExecutedContext filterContext)
{
base.OnActionExecuted(filterContext);
}
}
}
以上参考 http://www.cnblogs.com/huangxincheng/p/5671106.html