public class CustomerResourceFilterAttribute : Attribute, IResourceFilter
    {
        private static Dictionary<string,object> cacheDic=new Dictionary<string, object>();
        public void OnResourceExecuting(ResourceExecutingContext context)
        {
            var path=context.HttpContext.Request.Path; 
            if (cacheDic.ContainsKey(path))
            {
                context.Result = (IActionResult)cacheDic[path];
            }
            Console.WriteLine("CustomerResourceFilterAttribute.OnResourceExecuting");
        }
        public void OnResourceExecuted(ResourceExecutedContext context)
        {
            var path = context.HttpContext.Request.Path;
            cacheDic[path] = context.Result;
            Console.WriteLine("CustomerResourceFilterAttribute.OnResourceExecuted");
        }

        
    }

2、使用Filter

public class HomeController : Controller
    {
        private readonly ILogger<HomeController> _logger;

        public HomeController(ILogger<HomeController> logger)
        {
            _logger = logger;
            Console.WriteLine($"執(zhí)行 {this.GetType().Name} 構造函數(shù)");
        }

        [CustomerResourceFilter]
        public IActionResult Index()
        {
            ViewBag.Data = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
            return View();
        }
    }

3、前端頁面代碼

@{
    ViewData["Title"] = "Home Page";
}


<h3>來自于控制器的結果：@ViewBag.Data</h3>
<h3>來自于頁面的結果：@DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")</h3>

4、頁面效果

按F5可以看到頁面值的變化效果，"來自于控制器的結果"的值會一直不變，“來自于頁面的結果”隨著頁面刷新，值會一直變化

三、IAsyncResourceFilter（異步資源緩存）

public class CustomerAsyncResourceFilterAttribute : Attribute, IAsyncResourceFilter
    {
        private static Dictionary<string, object> cacheDic = new Dictionary<string, object>();
        public async Task OnResourceExecutionAsync(ResourceExecutingContext context, ResourceExecutionDelegate next)
        {
            Console.WriteLine("CustomerResourceFilterAttribute.OnResourceExecutionAsync Before");

            var path = context.HttpContext.Request.Path;
            if (cacheDic.ContainsKey(path))
            {
                context.Result = (IActionResult)cacheDic[path];
            }
            else
            {
                ResourceExecutedContext resource =await next.Invoke();
                cacheDic[path] = resource.Result; // 這句話的執(zhí)行就是去執(zhí)行控制器的構造函數(shù)+Action
                Console.WriteLine("CustomerResourceFilterAttribute.OnResourceExecutionAsync After");
            }
            

        }
    }