APP
.NET Core，.NET5默認(rèn)配置都是只加載一次，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(shè)置配置文件實(shí)時生效1.1配置
在Program.cs的CreateHostBuilder()處增加加載配置文件的時候，reloadOnChange:true。
這樣配置文件修改的時候，程序就會監(jiān)聽到文件發(fā)生變化，自動重新加載了。
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(yàn)證
appsettings.json文件內(nèi)容如下
{
"TestSetting": "123",
"AppOptions": {
"UserName": "zhangsan"
}
}代碼：
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();
}
}
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界面顯示：
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?把配置文件修改為：
{
"TestSetting": "abc",
"AppOptions": {
"UserName": "zhangsan123"
}
}刷新頁面，已經(jīng)發(fā)生變化：
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1.3 IOptions方式實(shí)時生效
新建AppOptions.cs類
/// <summary>
/// 配置文件
/// </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 IOptionsMonitor<AppOptions> _options;
public HomeController(ILogger<HomeController> logger, IConfiguration configuration, IOptionsMonitor<AppOptions> appOptions)
{
_logger = logger;
_configuration = configuration;
_options = appOptions;
}
public IActionResult Index()
{
string Name = _configuration["TestSetting"];
string Name2 = _options.CurrentValue.UserName;
ViewBag.Name = Name;
ViewBag.Name2 = Name2;
return View();
}
}
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IOptions有三種方式
//IOptions<T> //站點(diǎn)啟動后，獲取到的值永遠(yuǎn)不變
//IOptionsMonitor<T> //站點(diǎn)啟動后，如果配置文件有變化會發(fā)布事件 （加載配置時，reloadOnChange:true 必須為true）
//IOptionsSnapshot<T> //站點(diǎn)啟動后，每次獲取到的值都是配置文件里的最新值 （加載配置時，reloadOnChange:true 必須為true）
注意：?
IOptionsMonitor<T> 和 IOptionsSnapshot<T> 的最大區(qū)別是前者可以被其他的Singleton Services使用而后者不可以， 因?yàn)榍罢弑蛔詾镾ingleton 而后者是被注冊為Scoped，也就是說文件被修改了前者會立即Reload，而后者是在每個請求才被Reload。
例：
public class HomeController : Controller
{
private readonly ILogger<HomeController> _logger;
private UserService _userService;
public HomeController(ILogger<HomeController> logger, UserService userService)
{
_userService = userService;
}
public IActionResult Index()
{
string Name2 = _userService.GetName();
ViewBag.Name2 = Name2;
return View();
}
}
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public class UserService
{
private IOptionsMonitor<AppOptions> _options;
public UserService(IOptionsMonitor<AppOptions> appOptions)
{
_options = appOptions;
}
public string GetName()
{
var Name = _options.CurrentValue.UserName;
return Name;
}
}
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public void ConfigureServices(IServiceCollection services)
{
services.AddControllersWithViews();
services.Configure<AppOptions>(Configuration.GetSection("AppOptions"));
services.AddSingleton<UserService>();
}
上面的UserService是單例注入的，通過IOptionsMonitor<T>的方式是可以實(shí)現(xiàn)配置實(shí)時刷新的，而IOptionsSnapshot<T>啟動就會報錯。
1.4多個配置文件加載實(shí)時生效
增加多一個db配置文件
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修改Program.cs處CreateHostBuilder()，也是加載時加上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>();
});
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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();
}
}
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本文摘自 ：https://blog.51cto.com/u
