该筛选器是在系统出现异常时触发，可以对抛出的异常进行处理。所有的ExceptionFilter筛选器都是实现自IExceptionFilter接口
public interface IExceptionFilter
{
void OnException(ExceptionContext filterContext);
}
实现OnException方法来实现对异常的自定义处理
MVC4中实现了默认的异常处理机制，源码如下
public virtual void OnException(ExceptionContext filterContext)
{
if (filterContext == null)
{
throw new ArgumentNullException("filterContext");
}
if (filterContext.IsChildAction)
{
return;
} // If custom errors are disabled, we need to let the normal ASP.NET exception handler
// execute so that the user can see useful debugging information.
if (filterContext.ExceptionHandled || !filterContext.HttpContext.IsCustomErrorEnabled)
{
return;
} Exception exception = filterContext.Exception; // If this is not an HTTP 500 (for example, if somebody throws an HTTP 404 from an action method),
// ignore it.
if (new HttpException(null, exception).GetHttpCode() != )
{
return;
} if (!ExceptionType.IsInstanceOfType(exception))
{
return;
} string controllerName = (string)filterContext.RouteData.Values["controller"];
string actionName = (string)filterContext.RouteData.Values["action"];
HandleErrorInfo model = new HandleErrorInfo(filterContext.Exception, controllerName, actionName);
filterContext.Result = new ViewResult
{
ViewName = View,
MasterName = Master,
ViewData = new ViewDataDictionary<HandleErrorInfo>(model),
TempData = filterContext.Controller.TempData
};
filterContext.ExceptionHandled = true;
filterContext.HttpContext.Response.Clear();
filterContext.HttpContext.Response.StatusCode = ; // Certain versions of IIS will sometimes use their own error page when
// they detect a server error. Setting this property indicates that we
// want it to try to render ASP.NET MVC's error page instead.
filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
}
Application_Start中将HandleErrorAttribute添加到全局筛选器GlobalFilterCollection中，系统即会对异常进行对应的处理。
我们现在实现一个自定义的异常处理筛选器，在处理完后记录异常信息至日志文件中
public class MyExceptionHandleAttribute : HandleErrorAttribute
{
public MyExceptionHandleAttribute()
: base()
{
} public void OnException(ExceptionContext filterContext)
{
base.OnException(filterContext);
//记录日志
log.Info(filterContext.Exception);
}
}
在GlobalFilterCollection添加MyExceptionHandleAttribute 即可使用自定义的异常筛选器来处理