.Net Core Aop IResourceFilter

SportSky 2022-05-23 我要评论

一、简介

在.net core 中Filter分为以下六大类：

1、AuthorizeAttribute（权限验证）
2、IResourceFilter（资源缓存）
3、IActionFilter（执行方法前后的记录）
4、IResultFilter（结果生成前后扩展）
5、IAlwaysRun（响应结果的补充）
6、IExceptionFilter（异常处理）

二、IResourceFilter（同步资源缓存）

1、定义Filter

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($"执行 {this.GetType().Name} 构造函数");
        }

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

3、前端页面代码

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


<h3>来自于控制器的结果：@ViewBag.Data</h3>
<h3>来自于页面的结果：@DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")</h3>

4、页面效果

按F5可以看到页面值的变化效果，"来自于控制器的结果"的值会一直不变，“来自于页面的结果”随着页面刷新，值会一直变化

三、IAsyncResourceFilter（异步资源缓存）

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; // 这句话的执行就是去执行控制器的构造函数+Action
                Console.WriteLine("CustomerResourceFilterAttribute.OnResourceExecutionAsync After");
            }
            

        }
    }