.Net Core 修改默認的啟動端口
今天無意中發現一個變化，因為很久沒看.net core的項目了，發現項目啟動的默認端口已經不是5000了，記得很清楚，最早那還是.net core 1.x版本的時候，每次啟動都會默認是5000端口號，而現在不是了。借此機會在來說一下，關於.net core項目修改默認端口號的解決方案，我們最熟知的是一種解決方案就是直接在Program.cs中創建WebHost對象的時候，使用UseUrls()方法，配置要使用的端口，如下所示：
這是我們再熟悉不過的修改方法了，啟動以後，5001和5002端口都會開啟監聽，所以我們通過這兩個地址都會訪問到我們的網站。但是這種方式的缺點就是我們要修改代碼，重新編譯運行，這並不是我們想要的最好的解決方案，如果可以直接在配置文件中配置就完美了，便在一個個人博客裏看到了一個方法，地址：http://benfoster.io/blog/how-to-configure-kestrel-urls-in-aspnet-core-rc2 添加一個json文件，叫做hosting.json,意為服務配置,當然起什麽名字不重要，裏面只需要添加一個節點即可，內容如下：
{
"server.urls": "http://localhost:5001;http://localhost:5002"
}
添加了一個server.urls節點，然後再修改Program.cs文件，
運行後，顯示如下：
5001和5002端口都開啟了監聽。
這不禁引起了我的興趣，便翻起了關於這一塊兒的源碼。關於Hosting的源碼地址：https://github.com/aspnet/Hosting
下面我們層層深入，究其原因，查看IWebHost接口的Build方法：
/// <summary>
/// Builds the required services and an <see cref="IWebHost"/> which hosts a web application.
/// </summary>
public IWebHost Build()
{
if (_webHostBuilt)
{
throw new InvalidOperationException(Resources.WebHostBuilder_SingleInstance);
}
_webHostBuilt = true;
var hostingServices = BuildCommonServices(out var hostingStartupErrors);
var applicationServices = hostingServices.Clone();
var hostingServiceProvider = GetProviderFromFactory(hostingServices);
if (!_options.SuppressStatusMessages)
{
// Warn about deprecated environment variables
if (Environment.GetEnvironmentVariable("Hosting:Environment") != null)
{
Console.WriteLine("The environment variable ‘Hosting:Environment‘ is obsolete and has been replaced with ‘ASPNETCORE_ENVIRONMENT‘");
}
if (Environment.GetEnvironmentVariable("ASPNET_ENV") != null)
{
Console.WriteLine("The environment variable ‘ASPNET_ENV‘ is obsolete and has been replaced with ‘ASPNETCORE_ENVIRONMENT‘");
}
if (Environment.GetEnvironmentVariable("ASPNETCORE_SERVER.URLS") != null)
{
Console.WriteLine("The environment variable ‘ASPNETCORE_SERVER.URLS‘ is obsolete and has been replaced with ‘ASPNETCORE_URLS‘");
}
}
var logger = hostingServiceProvider.GetRequiredService<ILogger<WebHost>>();
// Warn about duplicate HostingStartupAssemblies
foreach (var assemblyName in _options.GetFinalHostingStartupAssemblies().GroupBy(a => a, StringComparer.OrdinalIgnoreCase).Where(g => g.Count() > 1))
{
logger.LogWarning($"The assembly {assemblyName} was specified multiple times. Hosting startup assemblies should only be specified once.");
}
AddApplicationServices(applicationServices, hostingServiceProvider);
var host = new WebHost(
applicationServices,
hostingServiceProvider,
_options,
_config,
hostingStartupErrors);
try
{
host.Initialize();
return host;
}
catch
{
// Dispose the host if there‘s a failure to initialize, this should clean up
// will dispose services that were constructed until the exception was thrown
host.Dispose();
throw;
}在Build方法裏主要是初始化了一個WebHost對象，再進入WebHost的源代碼，
private void EnsureServer()
{
if (Server == null)
{
Server = _applicationServices.GetRequiredService<IServer>();
var serverAddressesFeature = Server.Features?.Get<IServerAddressesFeature>();
var addresses = serverAddressesFeature?.Addresses;
if (addresses != null && !addresses.IsReadOnly && addresses.Count == 0)
{
var urls = _config[WebHostDefaults.ServerUrlsKey] ?? _config[DeprecatedServerUrlsKey];
if (!string.IsNullOrEmpty(urls))
{
serverAddressesFeature.PreferHostingUrls = WebHostUtilities.ParseBool(_config, WebHostDefaults.PreferHostingUrlsKey);
foreach (var value in urls.Split(new[] { ‘;‘ }, StringSplitOptions.RemoveEmptyEntries))
{
addresses.Add(value);
}
}
}
}
}不難找到是在上述方法裏面，添加的URL地址，在這行代碼中：
var urls = _config[WebHostDefaults.ServerUrlsKey] ?? _config[DeprecatedServerUrlsKey];
W這裏的URL判斷，如果當前默認的配置為空則使用後面的配置，而DepreacatedServerUrlsKey在一開始就已經定義了，
private static readonly string DeprecatedServerUrlsKey = "server.urls";
該參數的默認值為server.urls，所以我們在hosting.json中直接配置該鍵值對，.net core啟動後會自動讀取配置文件，使用配置的端口。其他相關配置，大家就自行搜索吧。
.Net Core 修改默認的啟動端口