ASP.NET MVC Action Filters中有趣的Http Headers

ASP.NET MVC Action Filters中有趣的Http Headers

        你想要你的Asp.net mvc 应用程序在一段时间后自动重定向一个指定的URL，是的你能用javascript中window.location来实现，除了javascript外呢？看这个代码：

[AutoRefresh(ControllerName = "Home", ActionName = "About", DurationInSeconds = 10)]
public ActionResult Index1()

[AutoRefresh(ActionName = "About", DurationInSeconds = 15)]
public ActionResult Index2()

[AutoRefresh(RouteName = "ByFavoriteRoute", DurationInSeconds = 30)]
public ActionResult Index3()

[AutoRefresh(DurationInSeconds = 45)]
public ActionResult Index4()

[AutoRefresh(ControllerName = "Home", ActionName = "About", DurationInSeconds = 10)]
public ActionResult Index1()

[AutoRefresh(ActionName = "About", DurationInSeconds = 15)]
public ActionResult Index2()

[AutoRefresh(RouteName = "ByFavoriteRoute", DurationInSeconds = 30)]
public ActionResult Index3()

[AutoRefresh(DurationInSeconds = 45)]
public ActionResult Index4()

如果浏览器在特定期间是闲置的，它将自动重定向到那个Action.如果你不指定任何action/controller/route，它将自动重定向当前URL．怎样？好的我只是使用/滥用一些http header,来看下面：

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = false)]
[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
public class AutoRefreshAttribute : ActionFilterAttribute
{
    public const int DefaultDurationInSeconds = 300; // 5 Minutes

    public AutoRefreshAttribute()
    {
        DurationInSeconds = DefaultDurationInSeconds;
    }

    public int DurationInSeconds
    {
        get;
        set;
    }

    public string RouteName
    {
        get;
        set;
    }

    public string ControllerName
    {
        get;
        set;
    }

    public string ActionName
    {
        get;
        set;
    }

    public override void OnResultExecuted(ResultExecutedContext filterContext)
    {
        string url = BuildUrl(filterContext);
        string headerValue = string.Concat(DurationInSeconds, ";Url=", url);

        filterContext.HttpContext.Response.AppendHeader("Refresh", headerValue);

        base.OnResultExecuted(filterContext);
    }

    private string BuildUrl(ControllerContext filterContext)
    {
        UrlHelper urlHelper = new UrlHelper(filterContext.RequestContext);
        string url;

        if (!string.IsNullOrEmpty(RouteName))
        {
            url = urlHelper.RouteUrl(RouteName);
        }
        else if (!string.IsNullOrEmpty(ControllerName) && !string.IsNullOrEmpty(ActionName))
        {
            url = urlHelper.Action(ActionName, ControllerName);
        }
        else if (!string.IsNullOrEmpty(ActionName))
        {
            url = urlHelper.Action(ActionName);
        }
        else
        {
            url = filterContext.HttpContext.Request.RawUrl;
        }

        return url;
    }
}

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = false)]
[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
public class AutoRefreshAttribute : ActionFilterAttribute
{
    public const int DefaultDurationInSeconds = 300; // 5 Minutes

    public AutoRefreshAttribute()
    {
        DurationInSeconds = DefaultDurationInSeconds;
    }

    public int DurationInSeconds
    {
        get;
        set;
    }

    public string RouteName
    {
        get;
        set;
    }

    public string ControllerName
    {
        get;
        set;
    }

    public string ActionName
    {
        get;
        set;
    }

    public override void OnResultExecuted(ResultExecutedContext filterContext)
    {
        string url = BuildUrl(filterContext);
        string headerValue = string.Concat(DurationInSeconds, ";Url=", url);

        filterContext.HttpContext.Response.AppendHeader("Refresh", headerValue);

        base.OnResultExecuted(filterContext);
    }

    private string BuildUrl(ControllerContext filterContext)
    {
        UrlHelper urlHelper = new UrlHelper(filterContext.RequestContext);
        string url;

        if (!string.IsNullOrEmpty(RouteName))
        {
            url = urlHelper.RouteUrl(RouteName);
        }
        else if (!string.IsNullOrEmpty(ControllerName) && !string.IsNullOrEmpty(ActionName))
        {
            url = urlHelper.Action(ActionName, ControllerName);
        }
        else if (!string.IsNullOrEmpty(ActionName))
        {
            url = urlHelper.Action(ActionName);
        }
        else
        {
            url = filterContext.HttpContext.Request.RawUrl;
        }

        return url;
    }
}

不能想像适当使用这个action filter，可能你能在你你要显示一些在线统计之类页面任何iframe中使用它．好的，现在让我们试试滥用这个Refeash header,这时它是一个相当通的场景．

你要安全的使用(标记为已认证)action,当会话过期时自动重定向到登陆页面.现试试这个:

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = false)]
[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
public class AutoRedirecToLogin : ActionFilterAttribute
{
    public override void OnResultExecuted(ResultExecutedContext filterContext)
    {
        string url = FormsAuthentication.LoginUrl;
        int durationInSeconds = ((filterContext.HttpContext.Session.Timeout * 60) + 10); // Extra 10 seconds

        string headerValue = string.Concat(durationInSeconds, ";Url=", url);

        filterContext.HttpContext.Response.AppendHeader("Refresh", headerValue);

        base.OnResultExecuted(filterContext);
    }
}

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = false)]
[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
public class AutoRedirecToLogin : ActionFilterAttribute
{
    public override void OnResultExecuted(ResultExecutedContext filterContext)
    {
        string url = FormsAuthentication.LoginUrl;
        int durationInSeconds = ((filterContext.HttpContext.Session.Timeout * 60) + 10); // Extra 10 seconds

        string headerValue = string.Concat(durationInSeconds, ";Url=", url);

        filterContext.HttpContext.Response.AppendHeader("Refresh", headerValue);

        base.OnResultExecuted(filterContext);
    }
}

当会话过期时,不需要额外的用户点击它将自动重定向到登陆页面.

警告:如果你要你的URL被搜索引擎收录为索引,那以不要使用Refresh meta 头(验证过Google,其它的不确定).例如,你的页面A要自动重定向页面B,那么页面A只有这个头,在那种情况下页面A将不会被索引.

Roni Schuetz 刚通知他有一个聚集 mvc action filters的项目在CodePlex 上, 对于他的项目这两个应该是最佳候选.

Author: Petter Liu   http://wintersun.cnblogs.com       Source