.Net Core Aop之IActionFilter

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、IActionFilter（同步）

1、定义Filter

public class CustomerActionFilterAttribute : Attribute, IActionFilter
    {
        /// <summary>
        /// 在XXAction执行之前
        /// </summary>
        /// <param name="context"></param>
        public void OnActionExecuting(ActionExecutingContext context)
        {
            Console.WriteLine("CustomerActionFilterAttribute.OnActionExecuting");
        }

        /// <summary>
        /// 在XXAction执行之后
        /// </summary>
        /// <param name="context"></param>
        public void OnActionExecuted(ActionExecutedContext context)
        {
            Console.WriteLine("CustomerActionFilterAttribute.OnActionExecuted");
        }

    }

2、使用Filter

public class Home1Controller : Controller
    {
        private readonly ILogger<HomeController> _logger;

        public Home1Controller(ILogger<HomeController> logger)
        {
            _logger = logger;
            Console.WriteLine($"执行 {this.GetType().Name} 构造函数");
        }

        [CustomerActionFilter]
        public IActionResult Index()
        {
            Console.WriteLine($"执行 Index 方法");
            return View();
        }
    }

3、扩展记录日志

public class CustomerActionFilterAttribute : Attribute, IActionFilter
    {

        private readonly ILogger<CustomerActionFilterAttribute> _logger;

        public CustomerActionFilterAttribute(ILogger<CustomerActionFilterAttribute> logger)
        {
            _logger = logger;
        }
        /// <summary>
        /// 在XXAction执行之前
        /// </summary>
        /// <param name="context"></param>
        public void OnActionExecuting(ActionExecutingContext context)
        {
            var para = context.HttpContext.Request.QueryString.Value;
            var controllerName = context.ActionDescriptor.RouteValues["controller"];
            var actionName = context.ActionDescriptor.RouteValues["action"];

            _logger.LogInformation($"当前请求的控制器是{controllerName},方法名{actionName},请求参数是{JsonConvert.SerializeObject(para)}");

        }

        /// <summary>
        /// 在XXAction执行之后
        /// </summary>
        /// <param name="context"></param>
        public void OnActionExecuted(ActionExecutedContext context)
        {
            var para = context.Result;
            var controllerName = context.ActionDescriptor.RouteValues["controller"];
            var actionName = context.ActionDescriptor.RouteValues["action"];
            _logger.LogInformation($"当前请求的控制器是{controllerName},方法名{actionName},请求结果是{JsonConvert.SerializeObject(para)}");

        }
    }

public class Home1Controller : Controller
    {
        private readonly ILogger<HomeController> _logger;

        public Home1Controller(ILogger<HomeController> logger)
        {
            _logger = logger;
            Console.WriteLine($"执行 {this.GetType().Name} 构造函数");
        }

        [TypeFilter(typeof(CustomerActionFilterAttribute))]
        public IActionResult Index(int id)
        {
            Console.WriteLine($"执行 Index 方法");
            ViewBag.Data = new { name = "11111" };
            return View();
        }
    }

三、IAsyncActionFilter（异步）

public class CustomerAsyncActionFilterAttribute : Attribute, IAsyncActionFilter
    {

        private readonly ILogger<CustomerAsyncActionFilterAttribute> _logger;

        public CustomerAsyncActionFilterAttribute(ILogger<CustomerAsyncActionFilterAttribute> logger)
        {
            _logger = logger;
        }
        public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
        {

            var para = context.HttpContext.Request.QueryString.Value;
            var controllerName = context.ActionDescriptor.RouteValues["controller"];
            var actionName = context.ActionDescriptor.RouteValues["action"];

            _logger.LogInformation($"当前请求的控制器是{controllerName},方法名{actionName},请求参数是{JsonConvert.SerializeObject(para)}");

            var excuteContext = await next.Invoke(); // 这句话就是去执行Action

            _logger.LogInformation($"当前请求的控制器是{controllerName},方法名{actionName},请求结果是{JsonConvert.SerializeObject(excuteContext.Result)}");

        }
    }

public class Home1Controller : Controller
    {
        private readonly ILogger<HomeController> _logger;

        public Home1Controller(ILogger<HomeController> logger)
        {
            _logger = logger;
            Console.WriteLine($"执行 {this.GetType().Name} 构造函数");
        }

        //[TypeFilter(typeof(CustomerActionFilterAttribute))]
        [TypeFilter(typeof(CustomerAsyncActionFilterAttribute))]
        public IActionResult Index(int id)
        {
            Console.WriteLine($"执行 Index 方法");
            ViewBag.Data = new { name = "11111" };
            return View();
        }
    }

四、总结

作用：该Filter可以记录Action执行前后的参数和结果

执行顺序：
1、执行控制器的构造函数
2、执行CustomerActionFilterAttribute.OnActionExecuting
3、执行Action方法
4、执行CustomerActionFilterAttribute.OnActionExecuted