C# MVC 中自定義權限特性[Authorize]中對於Ajax訪問的處理

在MVC中定義本身的權限特性。

下例中是簡單的登陸判斷，登陸信息存與Session中，若是Session中沒有登陸信息，那麼就不經過。

在處理無權限的時候，判斷當前請求是否爲Ajax請求，若是是Ajax請求，返回Json {state=-1,msg="請登陸"}，如過不是Ajax請求那麼就直接重定向到登陸頁面。

/// <summary>
/// 受權特性
/// </summary>
public class MyAuthorizeAttribute : AuthorizeAttribute
{
    string errcode = null;

    /// <summary>
    /// 受權核心
    /// </summary>
    /// <param name="httpContext"></param>
    /// <returns></returns>
    protected override bool AuthorizeCore(HttpContextBase httpContext)
    {
        var loginInfo = httpContext.Session["login"];
        if (loginInfo == null)
        {
            errcode = "NotLoggedIn";
            return false;
        }
        // 登陸用戶信息
        UserIdentity userIdentity = new UserIdentity((AdminInfo)loginInfo);
        httpContext.User = new UserPrincipal(userIdentity);

        return true;
    }

    /// <summary>
    /// 處理無權限請求
    /// </summary>
    /// <param name="filterContext"></param>
    protected override void HandleUnauthorizedRequest(AuthorizationContext filterContext)
    {
        // 沒有登陸
        if (errcode == "NotLoggedIn")
        {
            if (filterContext.HttpContext.Request.IsAjaxRequest())
            {
                filterContext.HttpContext.Response.StatusCode = (int)HttpStatusCode.OK;
                filterContext.Result = new JsonResult
                {
                    ContentEncoding = System.Text.Encoding.UTF8,
                    ContentType = "application/json",
                    JsonRequestBehavior = JsonRequestBehavior.AllowGet,
                    Data = new { state = -1, msg = "請從新登陸" },
                };
            }
            else
            {
                filterContext.Result = new RedirectResult("/Account/Login");
            }
        }
        return;
    }
}