得到 ASP.NET 當前的 Trust Level

得到 ASP.NET 當前的 Trust Level，摘自：dmitryr's blog

 AspNetHostingPermissionLevel GetCurrentTrustLevel() {  
     foreach (AspNetHostingPermissionLevel trustLevel in 
             new AspNetHostingPermissionLevel [] {  
                 AspNetHostingPermissionLevel.Unrestricted,  
                 AspNetHostingPermissionLevel.High,  
                 AspNetHostingPermissionLevel.Medium,  
                 AspNetHostingPermissionLevel.Low,  
                 AspNetHostingPermissionLevel.Minimal   
             } ) {  
         try {  
             new AspNetHostingPermission(trustLevel).Demand();  
         }  
         catch (System.Security.SecurityException ) {  
             continue;  
         }  
    
         return trustLevel;  
      }  
  
      return AspNetHostingPermissionLevel.None;  
 }