ActionFilter的使用场景及示例
ActionFilter里面有几个可以重写的事件：OnActionExecuting,OnActionExecuted,OnResultExecuting,OnResultExecuted 从字面我们大概就知道他们运行的顺序了。
示例：看四个方法的执行次序。定义一个继承ActionFilterAttribute并重写其内部方法的类。
public class SimpleFilterAttribute:ActionFilterAttribute
{
public int ID { get; set; }
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
File.AppendAllText(@"F:/actionlog.txt", this.ID +" "+ "OnActionExecuting <br>");
}
public override void OnActionExecuted(ActionExecutedContext filterContext)
{
File.AppendAllText(@"F:/actionlog.txt", this.ID + " " + "OnActionExecuted <br>");
}
public override void OnResultExecuting(ResultExecutingContext filterContext)
{
File.AppendAllText(@"F:/actionlog.txt", this.ID + " " + "OnResultExecuting <br>");
}
public override void OnResultExecuted(ResultExecutedContext filterContext)
{
File.AppendAllText(@"F:/actionlog.txt", this.ID + " " + "OnResultExecuted <br>");
}
}
在HomeController的Action方法上面标志。
[SimpleFilterAttribute(ID=1,Order=1)]
public ActionResult Index()
执行后，查看actionlog.txt文件可以看到是按照：OnActionExecuting,OnActionExecuted,OnResultExecuting,OnResultExecuted 次序执行的。
1.OnActionExecuting
在Action方法调用前使用，使用场景：如何验证登录等。
public class LoginFilterAttribute:ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
//当用户没有验证时
if (!filterContext.HttpContext.User.Identity.IsAuthenticated)
{
filterContext.Result = new RedirectToRouteResult("Default",
new RouteValueDictionary(new {action="Login"})
);
}
}
}
[LoginFilterAttribute]
public ActionResult Index()
2.OnActionExecuted
在Action方法调用后，result方法调用前执行，使用场景：异常处理
public class ErrorActionFilter:ActionFilterAttribute
{
public override void OnActionExecuted(ActionExecutedContext filterContext)
{
if (filterContext.Exception != null)
{
filterContext.Canceled = true;
filterContext.Result = new RedirectToRouteResult("Demo", new RouteValueDictionary(new { action = "ErrorPage" }));
}
}
}
[ErrorActionFilter]
public void ErrorHandler()
{
throw new Exception();
}
3.OnResultExecuting
在result执行前发生(在view 呈现前)，使用场景：设置客户端缓存，服务器端压缩.
明天写一下。
4.OnResultExecuted
在result执行后发生，使用场景：异常处理，页面尾部输出调试信息。
明天写一下。