.NET 5 修改配置不重启自动生效

.NET 5 修改配置不重启自动生效

.NET 5 修改配置不重启自动生效

.NET Core,.NET 5 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:

.NET 5 修改配置不重启自动生效

把配置文件修改为:

{
  "TestSetting": "abc",
  "AppOptions": {
    "UserName": "zhangsan123"
  }
}

刷新页面,已经发生变化:

.NET 5 修改配置不重启自动生效

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 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();
    }
}

IOptions有三种方式

1. IOptions<T>          //站点启动后,获取到的值永远不变
2. 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)
3. 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)

注意:

IOptionsMonitor<T> 和 IOptionsSnapshot<T> 的最大区别是前者可以被其他的Singleton Services使用而后者不可以, 因为前者被注册为Singleton 而后者是被注册为Scoped,也就是说文件被修改了前者会立即Reload,而后者是在每个请求才被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();
    }
}
public class UserService
{
    private IOptionsMonitor<AppOptions> _options;
    
    public UserService(IOptionsMonitor<AppOptions> appOptions)
    {
        _options = appOptions;
    }
    
    public string GetName()
    {
        var Name = _options.CurrentValue.UserName;
        return Name;
    }
}
public void ConfigureServices(IServiceCollection services)
{
    services.AddControllersWithViews();
    services.Configure<AppOptions>(Configuration.GetSection("AppOptions"));
    services.AddSingleton<UserService>();
}

上面的UserService是单例注入的,通过IOptionsMonitor<T>的方式是可以实现配置实时刷新的,而IOptionsSnapshot<T>启动就会报错。

1.4 多个配置文件加载实时生效

增加多一个db配置文件

.NET 5 修改配置不重启自动生效

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();
    }
}

转载自:博客园

原文作者:包子wxl

原文标题:.NET5修改配置不重启自动生效

原文链接:https://www.cnblogs.com/wei325/p/15277177.html

原文出处:博客园【包子wxl】

原文链接:https://www.cnblogs.com/wei325/p/15277177.html

本文观点不代表Dotnet9立场,转载请联系原作者。

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