using System;

using System.IO;

using Microsoft.Extensions.Configuration;

using Microsoft.Extensions.DependencyInjection;

using Microsoft.Extensions.Logging;

using Microsoft.Extensions.Logging.Console;

using ILogger = Microsoft.Extensions.Logging.ILogger;

​

namespace SampleApp

{

    public class Program

    {

        private readonly ILogger _logger;

​

        public Program()

        {

            var loggingConfiguration = new ConfigurationBuilder()

                .SetBasePath(Directory.GetCurrentDirectory())

                .AddJsonFile("logging.json", optional: false, reloadOnChange: true)

                .Build();

​

            // A Web App based program would configure logging via the WebHostBuilder.

            // Create a logger factory with filters that can be applied across all logger providers.

            var serviceCollection = new ServiceCollection()

                .AddLogging(builder =>

                {

                    builder

                        .AddConfiguration(loggingConfiguration.GetSection("Logging"))

                        .AddFilter("Microsoft", LogLevel.Warning)

                        .AddFilter("System", LogLevel.Warning)

                        .AddFilter("SampleApp.Program", LogLevel.Debug)

                        .AddConsole();

#if NET461

                    builder.AddEventLog();

#elif NETCOREAPP2_0

#else

#error Target framework needs to be updated

#endif

                });

​

            // providers may be added to a LoggerFactory before any loggers are created

​

​

            var serviceProvider = serviceCollection.BuildServiceProvider();

            // getting the logger using the class's name is conventional

            _logger = serviceProvider.GetRequiredService<ILogger<Program>>();

​

            ///// above logger works

            ///// following not working:

            /*

            ILoggerFactory loggerFactory = new LoggerFactory().AddConsole(LogLevel.Trace);

            ILoggerProvider console = new ConsoleLoggerProvider(new ConsoleLoggerSettings());

            loggerFactory.AddProvider(console);

            ILogger logger = loggerFactory.CreateLogger("foo");

            _logger = logger;

            */

        }

​

        public static void Main(string[] args)

        {

            new Program().Execute(args);

        }

​

        public void Execute(string[] args)

        {

            _logger.LogInformation("Starting");

​

            var startTime = DateTimeOffset.Now;

            _logger.LogInformation(1, "Started at '{StartTime}' and 0x{Hello:X} is hex of 42", startTime, 42);

            // or

            _logger.ProgramStarting(startTime, 42);

        }