Kestrel的ListenAnyIP和ListenLocalhost的区别

        /// <summary>
        /// Listens on ::1 and 127.0.0.1 with the given port. Requesting a dynamic port by specifying 0 is not supported
        /// for this type of endpoint.
        /// </summary>
        public void ListenLocalhost(int port, Action<ListenOptions> configure)
        {
            if (configure == null)
            {
                throw new ArgumentNullException(nameof(configure));
            }

            var listenOptions = new LocalhostListenOptions(port);
            ApplyEndpointDefaults(listenOptions);
            configure(listenOptions);
            ListenOptions.Add(listenOptions);
        }

    /// <summary>
        /// Listens on all IPs using IPv6 [::], or IPv4 0.0.0.0 if IPv6 is not supported.
        /// </summary>
        public void ListenAnyIP(int port, Action<ListenOptions> configure)
        {
            if (configure == null)
            {
                throw new ArgumentNullException(nameof(configure));
            }

            var listenOptions = new AnyIPListenOptions(port);
            ApplyEndpointDefaults(listenOptions);
            configure(listenOptions);
            ListenOptions.Add(listenOptions);
        }

  internal sealed class LocalhostListenOptions : ListenOptions
    {
        internal LocalhostListenOptions(int port)
            : base(new IPEndPoint(IPAddress.Loopback, port))
        {
            if (port == 0)
            {
                throw new InvalidOperationException(CoreStrings.DynamicPortOnLocalhostNotSupported);
            }
        }

        //绑定回环地址ipv4是127.0.0.1 ，iPV6是::1
        internal override async Task BindAsync(AddressBindContext context)
        {
            var exceptions = new List<Exception>();

            try
            {
                var v4Options = Clone(IPAddress.Loopback);
                await AddressBinder.BindEndpointAsync(v4Options, context).ConfigureAwait(false);
            }
            catch (Exception ex) when (!(ex is IOException))
            {
                context.Logger.LogWarning(0, CoreStrings.NetworkInterfaceBindingFailed, GetDisplayName(), "IPv4 loopback", ex.Message);
                exceptions.Add(ex);
            }

            try
            {
                var v6Options = Clone(IPAddress.IPv6Loopback);
                await AddressBinder.BindEndpointAsync(v6Options, context).ConfigureAwait(false);
            }
            catch (Exception ex) when (!(ex is IOException))
            {
                context.Logger.LogWarning(0, CoreStrings.NetworkInterfaceBindingFailed, GetDisplayName(), "IPv6 loopback", ex.Message);
                exceptions.Add(ex);
            }

            if (exceptions.Count == 2)
            {
                throw new IOException(CoreStrings.FormatAddressBindingFailed(GetDisplayName()), new AggregateException(exceptions));
            }

            // If StartLocalhost doesn't throw, there is at least one listener.
            // The port cannot change for "localhost".
            context.Addresses.Add(GetDisplayName());
        }

      
    }

 internal sealed class AnyIPListenOptions : ListenOptions
    {
        internal AnyIPListenOptions(int port)
            : base(new IPEndPoint(IPAddress.IPv6Any, port))
        {
        }

        //如果本机不支持 IPv6就绑定ipv4
        internal override async Task BindAsync(AddressBindContext context)
        {
            // when address is 'http://hostname:port', 'http://*:port', or 'http://+:port'
            try
            {
                await base.BindAsync(context).ConfigureAwait(false);
            }
            catch (Exception ex) when (!(ex is IOException))
            {
                context.Logger.LogDebug(CoreStrings.FormatFallbackToIPv4Any(IPEndPoint.Port));

                // for machines that do not support IPv6
                EndPoint = new IPEndPoint(IPAddress.Any, IPEndPoint.Port);
                await base.BindAsync(context).ConfigureAwait(false);
            }
        }
    }

 webBuilder.ConfigureKestrel(options =>
                    {
                        //1.ListenLocalhost方法
                        //options.ListenLocalhost(8081);

                        //2.ListenAnyIP方法
                        options.ListenAnyIP(8081);

                        //3.Listen方法
                        // options.Listen(IPAddress.Loopback, 8081);

                        // Setup a HTTP/2 endpoint without TLS.
                        options.ListenAnyIP(18081, o => o.Protocols =
                            HttpProtocols.Http1AndHttp2);
                    });