C# Online Compiler | .NET Fiddle

using System;
using System.ComponentModel.DataAnnotations;

namespace HelloWorldMvcApp
{
	public class SampleViewModel
	{

	}
}

@{
	Layout = null;
}

<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="utf-8">
		<meta http-equiv="X-UA-Compatible" content="IE=edge">
		<meta name="viewport" content="width=device-width, initial-scale=1">
		<title>session id</title>
		
	
	</head>
	
	<body>
			
		<h2>Index</h2>
		@ViewBag.Cache
		<hr />
		SesseionIDï¼
		@System.Web.HttpContext.Current.Session.SessionID	
		
	</body>
	</html>

 
@{
    Layout = null;
}
​
<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <title>session id</title>
        
    
    </head>
    
    <body>
            
        <h2>Index</h2>
        @ViewBag.Cache
        <hr />
        SesseionIDï¼•
        @System.Web.HttpContext.Current.Session.SessionID   
        
    </body>
    </html>

using System;
using System.Web;
using System.Web.Caching;
using System.Web.Mvc;

namespace HelloWorldMvcApp
{
	public class HomeController : Controller
	{
        public ActionResult Index()
        {
            ViewBag.Cache = GetCache("Index");
            return View();
        }

        private string GetCache(string key)
        {
            string result = "nothing";
            if (HttpRuntime.Cache.Get(key) == null)
            {
                string tmp = DateTime.Now.ToString("yyyy-MM-ddTHH:mm:ss+08:00");
                HttpRuntime.Cache.Add(key, tmp, null, DateTime.Now.AddSeconds(10), Cache.NoSlidingExpiration, CacheItemPriority.High, null);
                result = tmp;
            }
            else
            {
                result = (string)HttpRuntime.Cache.Get(key);
            }
            return result;
        }
	}
}

 
using System;
using System.Web;
using System.Web.Caching;
using System.Web.Mvc;
​
namespace HelloWorldMvcApp
{
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            ViewBag.Cache = GetCache("Index");
            return View();
        }
​
        private string GetCache(string key)
        {
            string result = "nothing";
            if (HttpRuntime.Cache.Get(key) == null)
            {
                string tmp = DateTime.Now.ToString("yyyy-MM-ddTHH:mm:ss+08:00");
                HttpRuntime.Cache.Add(key, tmp, null, DateTime.Now.AddSeconds(10), Cache.NoSlidingExpiration, CacheItemPriority.High, null);
                result = tmp;
            }
            else
            {
                result = (string)HttpRuntime.Cache.Get(key);
            }
            return result;
        }
    }
}