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.NET5修改配置不重启自动生效的实现_实用技巧_

2023-05-24 228人已围观

简介 .NET5修改配置不重启自动生效的实现_实用技巧_

.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(); }); 

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 _logger; private readonly IConfiguration _configuration; public HomeController(ILogger 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

 ///  /// 配置文件 ///  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(Configuration.GetSection("AppOptions")); } 

使用:

 public class HomeController : Controller { private readonly ILogger _logger; private readonly IConfiguration _configuration; private AppOptions _options; public HomeController(ILogger logger, IConfiguration configuration, IOptionsMonitor 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 //站点启动后,获取到的值永远不变 //IOptionsMonitor //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 //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) 

注意:

在 AddSingleton Services中使用 IOptionsMonitor也是无法实现配置立即生效的,而IOptionsSnapshot启动就会报错。

例:

 public class HomeController : Controller { private readonly ILogger _logger; private UserService _userService; public HomeController(ILogger logger, UserService userService) { _userService = userService; } public IActionResult Index() { string Name2 = _userService.GetName(); ViewBag.Name2 = Name2; return View(); } } 
 public class UserService { private AppOptions _options; public UserService(IOptionsMonitor appOptions) { _options = appOptions.CurrentValue; } public string GetName() { var Name = _options.UserName; return Name; } } 
 public void ConfigureServices(IServiceCollection services) { services.AddControllersWithViews(); services.Configure(Configuration.GetSection("AppOptions")); services.AddSingleton(); }

上面的UserService是单例注入的,通过IOptions的方式是实现不了配置实时刷新的,这种情况只能通过1.2中的 _configuration["AppOptions:UserName"]; 方式获取才能实现。

所以,这几种方式要根据情景变换使用。

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(); }); 

使用也是一样的:

 public class HomeController : Controller { private readonly ILogger _logger; private readonly IConfiguration _configuration; private AppOptions _options; public HomeController(ILogger logger, IConfiguration configuration, IOptionsMonitor 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(); } }

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