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所属分类：.NET技术
.NET Core，.NET5默认配置都是只加载一次，修改配置时都需要重启才能生效，如何能修改即时生效呢，下面来演示一遍。
一、设置配置文件实时生效
1.1配置
在Program.cs的CreateHostBuilder()处增加加载配置文件的时候，reloadOnChange:true。
这样配置文件修改的时候，程序就会监听到文件发生变化，自动重新加载了。
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验证
appsettings.json文件内容如下
{ "TestSetting": "123", "AppOptions": { "UserName": "zhangsan" } }
代码：
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(); } }
界面显示：
把配置文件修改为：
{ "TestSetting": "abc", "AppOptions": { "UserName": "zhangsan123" } }
刷新页面，已经发生变化：
1.3 IOptions方式实时生效
新建AppOptions.cs类
/// <summary> /// 配置文件 /// </summary> public class AppOptions { public string UserName { get; set; } }
在Startup.cs处把配置加到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有三种方式
//IOptions<T> //站点启动后，获取到的值永远不变 //IOptionsMonitor<T> //站点启动后，如果配置文件有变化会发布事件 （加载配置时，reloadOnChange:true 必须为true） //IOptionsSnapshot<T> //站点启动后，每次获取到的值都是配置文件里的最新值 （加载配置时，reloadOnChange:true 必须为true）
根据情景使用，这里使用IOptionsMonitor<T>。
1.4多个配置文件加载实时生效
增加多一个db配置文件
修改Program.cs处CreateHostBuilder()，也是加载时加上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>(); });
使用也是一样的：
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(); } }
