How to Get and check the application key values in web.config of Sharepoint site

In asp.net it is easy to access key values from web.config file using configuration assembly.Here in this post I will given an example to check whether the key value is exists or not for SharePoint site.The SharePoint provides  a class "webconfigurationManager" to access the key values from web.config file.Using the below bool method I will check the key value

 public static bool checkkeyvalues()
 {
using (SPSite sw = new SPSite(URL))
 {
 System.Configuration.Configuration cfig = WebConfigurationManager.OpenWebConfiguration("/", Sw.WebApplication.Name);

  AppSettingsSection aps = cfig.AppSettings;

return aps.ElementInformation.IsPresent;
 }
}