利用中间件处理异常

IExceptionFilter有些异常捕捉不到，可以利用中间件进行补充

1、在Program.cs添加以下代码

#region 中间件处理异常
{
    app.UseStatusCodePagesWithReExecute("/Home/Error/{0}");   //只要不是200，都能进来

    //拼装一个response输出
    app.UseExceptionHandler(errorApp =>
    {
        errorApp.Run(async context =>
        {
            context.Response.StatusCode = 200;
            context.Response.ContentType = "text/html";
            await context.Response.WriteAsync("<html lang='en'<body>\r\n");
            await context.Response.WriteAsync("ERROR!<br><br>\r\n");
            var exceptionHandlerPathFeature = context.Features.Get<IExceptionHandlerPathFeature>();
            Console.WriteLine("&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&");
            Console.WriteLine($"{exceptionHandlerPathFeature?.Error.Message}");
            Console.WriteLine("&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&");
            if(exceptionHandlerPathFeature?.Error is FileNotFoundException)
            {
                await context.Response.WriteAsync("File error thrown!<br><br>\r\n");
            }
            await context.Response.WriteAsync("<a href='/'>Home</a><br>\r\n");
            await context.Response.WriteAsync("</body></html>\r\n");
            await context.Response.WriteAsync(new string(' ', 512));
        });
    });
}
#endregion