Asp.net Core過濾器

1. Asp.net Core五類過濾器：Authorization Filter、Resource Filter、Acton Filter、Exception Filter、Result Filter。優先級逐次遞減。
2. 過濾器使用
   1. 　

      public class GlobalFiler: Attribute,IAuthorizationFilter
          {
              public void OnAuthorization(AuthorizationFilterContext context)
              {
                  context.Result = new JsonResult("全局權限設置");
              }
      
          }
      public class MyFilter : Attribute,IActionFilter,IOrderedFilter
          {
              public int Order { get; set; }
      
              public void OnActionExecuted(ActionExecutedContext context)
              {
              }
      
              public void OnActionExecuting(ActionExecutingContext context)
              {
              }
          }
      
      //ActionFilterAttribute繼承了Attribute、IActionFilter、IOrderedFilter等 public class MyFilter2 : ActionFilterAttribute
          {
      　　     public override void OnActionExecuting(ActionExecutingContext context)
              {
       //如果失敗，頁面提示 
                  context.Result = new JsonResult("MyFilter2設置，無權限訪問");
              }
          }

       

3. 過濾器注冊，分為兩種：全局注冊和用Attribute區域注冊，用在特定Action上。
   1. 全局注冊Startup.cs

      public void ConfigureServices(IServiceCollection services)
              {
                  services.AddMvc(config => config.Filters.Add(new GlobalFiler()));
                  //services.AddMvc(config => config.Filters.Add(typeof(GlobalFiler)));
              }

       

   2. 區域注冊

      [Route("api/[controller]")]
          [MyFilter(Order = 1)]
          public class ValuesController : Controller
          {
              // GET api/values
              [HttpGet]
              [MyFilter2(Order = 0)]
              public IEnumerable<string> Get()
              {
                  return new string[] { "value1", "value2" };
              }
          }

       

4. 過濾器執行順序
   1. 默認執行順序：全局過濾器優先於控制器過濾器，控制器過濾器優先於Action方法過濾器。　　
   2. 通過IOrderedFilter覆蓋默認執行順序，此接口公開Order屬性表示優先級，Order值越小優先級越高。

　　參考文檔：https://www.cnblogs.com/tdfblog/p/filters-in-aspnet-core-mvc.html