ActionFilterAttribute

1、新建类CustomActionResultFilterAttribute，继承ActionFilterAttribute

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using Project6.Model;

namespace Project6.Utility.Filters
{
    public class CustomActionResultFilterAttribute:ActionFilterAttribute
    {
        private readonly ILogger<CustomActionResultFilterAttribute> _ILogger;

        public CustomActionResultFilterAttribute(ILogger<CustomActionResultFilterAttribute> iLogger)
        {
            this._ILogger = iLogger;
        }

        public override void OnActionExecuting(ActionExecutingContext context)
        {
            var para = context.HttpContext.Request.QueryString.Value;
            var controllerName = context.HttpContext.GetRouteValue("controller");
            var actionName = context.HttpContext.GetRouteValue("action");
            _ILogger.LogInformation($"执行{controllerName} - {actionName},参数为：{para}");
        }

        public override void OnActionExecuted(ActionExecutedContext context)
        {
            var result = Newtonsoft.Json.JsonConvert.SerializeObject(context.Result);
            var controllerName = context.HttpContext.GetRouteValue("controller");
            var actionName = context.HttpContext.GetRouteValue("action");
            _ILogger.LogInformation($"执行{controllerName} - {actionName},结果为：{result}");
        }

        public  override async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
        {
            var controllerName = context.HttpContext.GetRouteValue("controller");
            var actionName = context.HttpContext.GetRouteValue("action");
            var para = context.HttpContext.Request.QueryString.Value;
            _ILogger.LogInformation($"执行{controllerName} - {actionName}方法:参数为:{para}");

            //去执行控器里面的Action
            ActionExecutedContext executedContext = await next.Invoke();

            var result = Newtonsoft.Json.JsonConvert.SerializeObject(executedContext.Result);
            _ILogger.LogInformation($"执行{controllerName} - {actionName}方法:结果为:{result}");
        }

        public override void OnResultExecuting(ResultExecutingContext context)
        {
            if (context.Result is JsonResult)
            {
                JsonResult jsonResult = (JsonResult)context.Result;
                context.Result = new JsonResult(new AjaxResult()
                {
                    Success = true,
                    Message = "OK",
                    Data = jsonResult.Value
                });
            }
        }

        public override void OnResultExecuted(ResultExecutedContext context)
        {
            base.OnResultExecuted(context);
        }

        public override async Task OnResultExecutionAsync(ResultExecutingContext context, ResultExecutionDelegate next)
        {
            if (context.Result is JsonResult)
            {
                JsonResult jsonResult = (JsonResult)context.Result;
                context.Result = new JsonResult(new AjaxResult()
                {
                    Success = true,
                    Message = "OK",
                    Data = jsonResult.Value
                });
            }

            await next.Invoke();
        }
    }
}

2、新建类AjaxResult

namespace Project6.Model
{
    public class AjaxResult
    {
        public bool Success { get; set; }
        public string Message { get; set; }
        public object Data { get; set; }

    }
}

3、新建控制器CustomActionResultFilterController

using Microsoft.AspNetCore.Mvc;
using Project6.Utility.Filters;

namespace Project6.Controllers
{
    public class CustomActionResultFilterController : Controller
    {
        [TypeFilter(typeof(CustomActionResultFilterAttribute))]
        public IActionResult Index(int id)
        {
            int _id = id;
            return Json(new
            {
                Id = _id,
                Name = "net"
            });
        }
    }
}

4、在各个方法开始处设置断点，执行/CustomActionResultFilter?id=1

可以发现程序执行顺序为：OnActionExecutionAsync--->

执行到 ActionExecutedContext executedContext = await next.Invoke();时跳到控制器CustomActionResultFilterController的Index-->

执行为Action方法之后，继续执行 ActionExecutedContext executedContext = await next.Invoke();之后的代码-->

OnResultExecutionAsync

结论：1、ActionFilterAttribute抽像类继承 Attribute, IActionFilter, IFilterMetadata, IAsyncActionFilter, IResultFilter, IAsyncResultFilter, IOrderedFilter

 

 只要继承它即可以实现常见的过滤方法。

2、当同步方法和异步方法同时存在，程序只处理异步方法

3、OnActionExecutionAsync方法在Action方法执行前后执行

4、OnResultExecutionAsync方法在Action 返回结果之后执行