ASP.NET MVC Filter基础

1. IAuthorizationFilter  　　                              可用于登录检查，判断是否登录
2. IActionFilter                                                  Action拦截器 方法执行前后拦截
3. IResultFilter                                                  Result拦截器 方法返回前后拦截
4. ExceptionFilter                                             Exception拦截器 异常处理拦截    同一返回错误界面  
5. FilterAttribute ||1/2/3/4                                  自定义拦截器（多继承上面任意拦截器实现）

IAuthorizationFilter

public class LoginFilter : IAuthorizationFilter
    {
        public void OnAuthorization(AuthorizationContext filterContext)
        {
            //1、控制器+方法
            string controllerName1 = filterContext.RouteData.Values["controller"].ToString();
            string actionName1 = filterContext.RouteData.Values["action"].ToString();

            //2、建议：
            string controllerName2 = filterContext.ActionDescriptor.ControllerDescriptor.ControllerName;
            string actionName2 = filterContext.ActionDescriptor.ActionName;

            //filterContext.HttpContext.Response.Write("控制器：" + controllerName2 + "<br/>");         
            //filterContext.HttpContext.Response.Write("Action：" + actionName2 + "<br/>"); 
            if (controllerName2 == "Login" && actionName2 == "index"|| controllerName2 == "Exception")
            {
            }
            else
            {
                if (filterContext.HttpContext.Session["username"]==null)
                {
                    filterContext.Result = new ContentResult() {Content="没有登录" };
                }
            }

                                                                                                
        }
    }

IActionFilter  .

 public class ActionFilter : IActionFilter
    {
        public void OnActionExecuted(ActionExecutedContext filterContext)
        {
            string controllerName = filterContext.ActionDescriptor.ControllerDescriptor.ControllerName;
            string actionName = filterContext.ActionDescriptor.ActionName;
            File.AppendAllText(HttpContext.Current.Server.MapPath("~/IActionFilter.txt"), $"OnActionExecuted: {controllerName}-{actionName} 
");   
        }

        public void OnActionExecuting(ActionExecutingContext filterContext)
        {
            string controllerName = filterContext.ActionDescriptor.ControllerDescriptor.ControllerName;
            string actionName = filterContext.ActionDescriptor.ActionName;
            File.AppendAllText(HttpContext.Current.Server.MapPath("~/IActionFilter.txt"), $"OnActionExecuting: {controllerName}-{actionName} 
");
        }
    }

IResultFilter

    public class ResultFilter : IResultFilter
    {
        public void OnResultExecuted(ResultExecutedContext filterContext)
        {
             
            File.AppendAllText(HttpContext.Current.Server.MapPath("~/IResultFilter.txt"), $"OnResultExecuted 
");
        }

        public void OnResultExecuting(ResultExecutingContext filterContext)
        {                                                                    
            File.AppendAllText(HttpContext.Current.Server.MapPath("~/IResultFilter.txt"), $"OnResultExecuting 
");
        }
    }

ExceptionFilter ：

   public class ExceptionFilter : IExceptionFilter
    {
        public void OnException(ExceptionContext filterContext)
        {
            //1、获取异常对象
            Exception ex = filterContext.Exception;       
            //2、记录异常日志
            File.AppendAllText(HttpContext.Current.Server.MapPath("~/IExceptionFilter.txt"), $"OnException {ex.Message} 
");
            //3、重定向友好页面
            filterContext.Result = new RedirectResult("~/Exception/NoFund");
            //4.标记错误已处理
            filterContext.ExceptionHandled = true;                         
        }
    }

FilterAttribute 

    /// <summary>
    /// 自定义拦截
    /// </summary>
    public class LogFilterAttribute : FilterAttribute, IActionFilter
    {
        public void OnActionExecuted(ActionExecutedContext filterContext)
        {
            string controllerName = filterContext.ActionDescriptor.ControllerDescriptor.ControllerName;
            string actionName = filterContext.ActionDescriptor.ActionName;
            File.AppendAllText(HttpContext.Current.Server.MapPath("~/LogFilterAttribute.txt"), $"OnActionExecuted: {controllerName}-{actionName} 
");
        }

        public void OnActionExecuting(ActionExecutingContext filterContext)
        {
            string controllerName = filterContext.ActionDescriptor.ControllerDescriptor.ControllerName;
            string actionName = filterContext.ActionDescriptor.ActionName;
            File.AppendAllText(HttpContext.Current.Server.MapPath("~/LogFilterAttribute.txt"), $"OnActionExecuting: {controllerName}-{actionName} 
");
        }
    }

结果显示：