乘风原创程序

  • asp.net mvc core管道及拦截器的理解
  • 2020/5/17 10:21:21
  • 今天来看一下asp.net core的执行管道。先看下官方说明:

     从上图可以抛光,asp.net core的执行顺序是,当收到一个请求后,request请求会先经过已注册的中间件,然后会进入到mvc的拦截器管道:

    进入mvc管道后,根据以上顺序执行过滤校正。

    OK,根据以上说明下面我们新建一个MVC的演示,将执行方式切换为控台运行:

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
     services.AddControllersWithViews(config=> 
     {
      Console.WriteLine("execute C");
      //config.Filters.Add(new AsyncAuthorizationFilter());
      config.Filters.Add(new AuthorizationFilter());
      config.Filters.Add(new ResourceFilter());
      //config.Filters.Add(new AsyncResourceFilter());
      config.Filters.Add(new ActionFilter());
      //config.Filters.Add(new AsyncActionFilter());
      config.Filters.Add(new ResultFilter());
      //config.Filters.Add(new AsyncResultFilter());
      config.Filters.Add(new ExceptionFilter());
      //config.Filters.Add(new AsyncExceptionFilter());
      Console.WriteLine("execute D");
     });
     services.AddSession(config=> {
      Console.WriteLine("execute E");
     });
    }
    
    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
     if (env.IsDevelopment())
     {
      app.UseDeveloperExceptionPage();
     }
     else
     {
      app.UseExceptionHandler("/Home/Error");
     }
     app.UseStaticFiles();
     app.UseRouting();
     app.UseAuthorization();
     app.Use(async (context, next) =>
     {
      Console.WriteLine("execute F");
      await context.Response.WriteAsync("hello world");
      Console.WriteLine("execute G");
     });
     //app.UseSession();
     app.UseEndpoints(endpoints =>
     {
      Console.WriteLine("execute A");
      endpoints.MapControllerRoute(
       name: "default",
       pattern: "{controller=Home}/{action=Index}/{id?}");
      Console.WriteLine("execute B");
     });
    }

    执行结果:

    不多做解释,从从这里我们可以抛光符合官方说明文档。

    看完中间件执行顺序,下面我们来了解下mvc拦截器的使用与执行顺序。

    根据mvc filter管道执行顺序,我们分别来看下用法:

    1)AuthorizationFilter:该拦截器是优先级最高的,当请求进入mvc后,首先会被AuthorizationFilter验证是否有权限访问,无权限则跳出。

    同步用法:

    public class AuthorizationFilter: IAuthorizationFilter
    {
     public void OnAuthorization(AuthorizationFilterContext context)
     {
      context.HttpContext.Response.WriteAsync("authorization filter \r");
     }
    }

    异步用法:

    public class AsyncAuthorizationFilter: IAsyncAuthorizationFilter
    {
     public async Task OnAuthorizationAsync(AuthorizationFilterContext context)
     {
      await context.HttpContext.Response.WriteAsync($"async authorization filter in \r");
     }
    }

    2)ResourceFilter:该拦截器是作为第二道拦截器,

    OnResourceExecuting在模型绑定之前运行代码。OnResourceExecuted在管道的其余阶段完成之后运行代码。

    同步用法:

    public class ResourceFilter: IResourceFilter
    {
     public void OnResourceExecuting(ResourceExecutingContext context)
     {
      context.HttpContext.Response.WriteAsync($"resource executing\r");
     }
     public void OnResourceExecuted(ResourceExecutedContext context)
     {
      context.HttpContext.Response.WriteAsync($"resource executed \r");
     }
    }

    异步用法:

    public class AsyncResourceFilter: IAsyncResourceFilter
    {
     public async Task OnResourceExecutionAsync(ResourceExecutingContext context, ResourceExecutionDelegate next)
     {
      await context.HttpContext.Response.WriteAsync($" async resource filter in. \r\n");
      await next();
      await context.HttpContext.Response.WriteAsync($"async resource filter out. \r\n");
     }
    }

    3)ActionFilter:在调用操作方法之前和之后立即运行代码;可以更改传递到操作中的参数;可以更改从操作返回的结果。

    同步用法:

    public class ActionFilter: IActionFilter
    {
     public void OnActionExecuting(ActionExecutingContext context)
     {
      context.HttpContext.Response.WriteAsync($"action executing \r");
     }
    
     public void OnActionExecuted(ActionExecutedContext context)
     {
      context.HttpContext.Response.WriteAsync($"action executed . \r");
     }
    }

    异步用法:

    public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
    {
     await context.HttpContext.Response.WriteAsync($"async action execution in. \r\n");
     await next();
     await context.HttpContext.Response.WriteAsync($"async action execution out. \r\n");
    }

    4)OnException:在向响应正文写入任何内容之前,对声明处理的异常应用变量策略。

    同步用法:

    public class ExceptionFilter: IExceptionFilter
    {
     public void OnException(ExceptionContext context)
     {
      context.HttpContext.Response.WriteAsync($"exception \r");
     }
    }

    异步用法:

    public class AsyncExceptionFilter: IAsyncExceptionFilter
    {
     public Task OnExceptionAsync(ExceptionContext context)
     {
      context.HttpContext.Response.WriteAsync($"exception async \r");
      return Task.CompletedTask;
     }
    }

    5)ResultFilter:在执行操作结果之前和之后立即运行代码;仅当操作方法成功执行时,其才会运行。 可以设置格式化返回结果:

    同步操作:

    public class ResultFilter: IResultFilter
    {
     public void OnResultExecuting(ResultExecutingContext context)
     {
      context.HttpContext.Response.WriteAsync($"result executing\r");
     }
     public void OnResultExecuted(ResultExecutedContext context)
     {
      context.HttpContext.Response.WriteAsync($"result executed \r");
     }
    }

    异步用法:

    public class AsyncResultFilter: IAsyncResultFilter
    {
     public async Task OnResultExecutionAsync(ResultExecutingContext context, ResultExecutionDelegate next)
     {
      await context.HttpContext.Response.WriteAsync($"result execution async in \r");
      await next();
      await context.HttpContext.Response.WriteAsync($"result execution async out. \r");
     }
    }

    注册方式我们就是用分区注册,已经在上面说明,不再多做表述,下面我们看下运行情况(页面输出):

     定义一个异常看下结果:

    public IActionResult Privacy()
    {
      throw new Exception("error");
    }

    ok,目标达成,不多说了,下次再看拦截器具体实现。

    参考文档:ASP.NET Core 中的筛选器

    总结