.NET Core，.NET5預設配置都是隻載入一次，修改配置時都需要重啟才能生效，如何能修改即時生效呢，下面來演示一遍。
一、設定配置檔案實時生效
1.1配置
在Program.cs的CreateHostBuilder()處增加載入配置檔案的時候，reloadOnChange:true。
這樣配置檔案修改的時候，程式就會監聽到檔案發生變化，自動重新載入了。
public static IHostBuilder CreateHostBuilder(string[] args) =>
Host.CreateDefaultBuilder(args)
.ConfigureAppConfiguration((context, config) =>
{
config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true);
})
.ConfigureWebHostDefaults(webBuilder =>
{
webBuilder.UseStartup<Startup>(); });
1.2驗證
appsettings.json檔案內容如下
{
"TestSetting": "123",
"AppOptions": {
"UserName": "zhangsan"
}
}
程式碼：
public class HomeController : Controller
{
private readonly ILogger<HomeController> _logger;
private readonly IConfiguration _configuration;
public HomeController(ILogger<HomeController> logger, IConfiguration configuration)
{
_logger = logger;
_configuration = configuration;
} public IActionResult Index()
{
string Name = _configuration["TestSetting"];
string Name2 = _configuration["AppOptions:UserName"];
ViewBag.Name = Name;
ViewBag.Name2 = Name2;
return View();
}
}
介面顯示：
把配置檔案修改為：
{
"TestSetting": "abc",
"AppOptions": {
"UserName": "zhangsan123"
}
}
重新整理頁面，已經發生變化：
1.3 IOptions方式實時生效
新建AppOptions.cs類
/// <summary>
/// 配置檔案
/// </summary>
public class AppOptions
{
public string UserName { get; set; }
}
在Startup.cs處把配置加到Options
public void ConfigureServices(IServiceCollection services)
{
services.AddControllersWithViews();
services.Configure<AppOptions>(Configuration.GetSection("AppOptions"));
}
使用：
public class HomeController : Controller
{
private readonly ILogger<HomeController> _logger;
private readonly IConfiguration _configuration;
private AppOptions _options;
public HomeController(ILogger<HomeController> logger, IConfiguration configuration, IOptionsMonitor<AppOptions> appOptions)
{
_logger = logger;
_configuration = configuration;
_options = appOptions.CurrentValue;
} public IActionResult Index()
{
string Name = _configuration["TestSetting"];
string Name2 = _options.UserName;
ViewBag.Name = Name;
ViewBag.Name2 = Name2;
return View();
}
}
IOptions有三種方式
//IOptions<T> //站點啟動後，獲取到的值永遠不變
//IOptionsMonitor<T> //站點啟動後，如果配置檔案有變化會發布事件 （載入配置時，reloadOnChange:true 必須為true）
//IOptionsSnapshot<T> //站點啟動後，每次獲取到的值都是配置檔案裡的最新值 （載入配置時，reloadOnChange:true 必須為true）
根據情景使用，這裡使用IOptionsMonitor<T>。
1.4多個配置檔案載入實時生效
增加多一個db配置檔案
修改Program.cs處CreateHostBuilder()，也是載入時加上reloadOnChange:true 就可以了。
public static IHostBuilder CreateHostBuilder(string[] args) =>
Host.CreateDefaultBuilder(args)
.ConfigureAppConfiguration((context, config) =>
{
config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true);
config.AddJsonFile("Configs/dbsetting.json", optional: true, reloadOnChange: true);
})
.ConfigureWebHostDefaults(webBuilder =>
{
webBuilder.UseStartup<Startup>(); });
使用也是一樣的：
public class HomeController : Controller
{
private readonly ILogger<HomeController> _logger;
private readonly IConfiguration _configuration;
private AppOptions _options;
public HomeController(ILogger<HomeController> logger, IConfiguration configuration, IOptionsMonitor<AppOptions> appOptions)
{
_logger = logger;
_configuration = configuration;
_options = appOptions.CurrentValue;
} public IActionResult Index()
{
string Name = _configuration["TestSetting"];
string Name2 = _configuration["db:connection1"];
ViewBag.Name = Name;
ViewBag.Name2 = Name2;
return View();
}
}