Asp.Net.Core5 筛选器

一，ActionFilterAttribute

public class CustomActionFilterAttribute: ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext context)
        {
            base.OnActionExecuting(context);
        }
        public override void OnActionExecuted(ActionExecutedContext context)
        {
            base.OnActionExecuted(context);
        }

        public override void OnResultExecuting(ResultExecutingContext context)
        {
            base.OnResultExecuting(context);
        }

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

二，ExceptionFilterAttribute

 public class CustomExceptionFilterAttribute : ExceptionFilterAttribute
    {
        //出现异常处理
        public override void OnException(ExceptionContext context)
        {
            //返回错误信息
            context.Result = new JsonResult(new
            {
                errcode = 1,
                message = context.Exception.Message
            });
        }
    }

三，ResultFilterAttribute

 public class CustomResultFilterAttribute: ResultFilterAttribute
    {
        public CustomResultFilterAttribute() { } //构造函数
        //执行前
        public override void OnResultExecuting(ResultExecutingContext context)
        {
            ////请求方法对象
           // context.HttpContext.Response;
            //context.HttpContext.Request;
            base.OnResultExecuting(context);
        }
        //执行后
        public override void OnResultExecuted(ResultExecutedContext context)
        {
            base.OnResultExecuted(context);
        }
    }

四，作用域

1，Action  标识Filter

2，Controller  标识Filter

 [Filters.CustomResultFilter]
 [Filters.CustomExceptionFilter]
 [Filters.CustomActionFilter]
 public IActionResult Index()
 {
     return View();
 }

3，所有Action ，Controller 

在Startup.cs 添加    options.Filters.Add(typeof(Filters.CustomeActionFilter));

 public void ConfigureServices(IServiceCollection services)
        {
            services.AddRazorPages().AddRazorRuntimeCompilation();
            services.AddSession();//注册Session
            services.AddControllersWithViews(options =>
            {
                //添加筛选
                options.Filters.Add(typeof(Filters.CustomeActionFilter));
            });
        }

五，筛选器执行-顺序设置

默认属性可以直接设置为具体int指

 [Filters.CustomExceptionFilter(Order =int.MinValue)]
public IActionResult Index()
{
     return View();
}

//全局 
options.Filters.Add(typeof(Filters.CustomeActionFilter),int.MaxValue);

六，ServiceFilterAttribute

Action中（CustomeActionFilter） 将从依赖注入容器DI中获取得到

public void ConfigureServices(IServiceCollection services) { 
   services.AddScoped<Filters.CustomeActionFilter>();
}

[ServiceFilter(typeof(Filters.CustomeActionFilter),Order =int.MaxValue)]
public IActionResult Index()
{
   return View();
}

七，TypeFilterAttribute

不需注册依赖注入，自带DI容器实现的依赖。

Microsoft.Extensions.DependencyInjection.ObjectFactory  对类型实例化

[TypeFilter(typeof(Filters.CustomeActionFilter),Order =int.MaxValue)]
public IActionResult Index()
{
   return View();
}