2.2.3 核心模块--配置

• IConfiguration

• Options

ASP.NET Core 中的配置：https://docs.microsoft.com/zh-cn/aspnet/core/fundamentals/configuration/?view=aspnetcore-5.0

IConfiguration

• IConfiguration 的使用

• 层级对象配置到 key-value 键值对转换

• 通过环境变量修改日志级别

• 通过命令行修改日志级别

IConfiguration 的使用

appsettings.json

{"Logging": {"LogLevel": {"Default": "Information","Microsoft": "Warning","Microsoft.Hosting.Lifetime": "Information"}},"AllowedHosts": "*"
}

新增 ConfigController.cs

namespace HelloApi.Controllers
{[ApiController][Route("[controller]")]public class ConfigController : Controller{private readonly IConfiguration _configuration;public ConfigController(IConfiguration configuration){_configuration = configuration;}[HttpGet]public IActionResult GetConfigurations(){var result = new List<string>();foreach (var key in _configuration.AsEnumerable()){result.Add($"Key: {key.Key}, value: {key.Value}");}return Ok(result);}}
}

启动程序，访问：https://localhost:5001/config

不仅得到 appsettings.json 的配置， 还可以得到环境变量配置

可以在 ConfigureAppConfiguration 中清除所有配置，再添加自己需要的配置，后面添加的配置会覆盖前面的配置

.ConfigureAppConfiguration((hostingContext, config) =>
{config.Sources.Clear();var env = hostingContext.HostingEnvironment;config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true).AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);
})

启动程序，访问：https://localhost:5001/config

这样可以得到自己添加的配置

层级对象配置到 key-value 键值对转换

appsettings.json

{"Logging": {"LogLevel": {"Default": "Information","Microsoft": "Warning","Microsoft.Hosting.Lifetime": "Information"}},"AllowedHosts": "*"
}

通过冒号读取下一级配置（Windows），Linux 上通过下划线

[HttpGet]
public IActionResult GetConfigurations()
{var result = new List<string>();//foreach (var key in _configuration.AsEnumerable())//{//    result.Add($"Key: {key.Key}, value: {key.Value}");//}return Content(string.Format("Default Log Level: {0}", _configuration["Logging:LogLevel:Default"]));
}

启动程序，输出如下：

Default Log Level: Debug

通过环境变量修改日志级别

在 launcSettings.json 中添加 Trace 日志级别

"environmentVariables": {"ASPNETCORE_ENVIRONMENT": "Development","Logging__LogLevel__Default": "Trace"}

在 CreateHostBuilder 的时候添加环境变量配置

config.AddEnvironmentVariables();

启动程序，输出如下：

Default Log Level: Trace

通过命令行修改日志级别

CreateHostBuilder

config.AddCommandLine(source =>
{source.Args = args;
});

在命令行中设置

set Logging__LogLevel__Default=Warning

Options

• 通过 ConfigurationBinder 操作 Options

• 通过 Configure 绑定 Option

通过 ConfigurationBinder 操作 Options

新建 MyOption.cs

namespace HelloApi
{public class MyOption{public string Name { get; set; }public int Age { get; set; }}
}

在 appsettings.json 中新增一个节点

"MyOption": {"Name": "Mingson","Age": 25 },

在 ConfigureServices 中绑定

var myOption = new MyOption();
Configuration.GetSection("MyOption").Bind(myOption);
// 单例注入到全局中
services.AddSingleton(myOption);

在 ConfigController 中注入，与获取

private readonly MyOption _myOption;public ConfigController(IConfiguration configuration, MyOption myOption)
{_configuration = configuration;_myOption = myOption;
}[HttpGet("option")]
public IActionResult GetOption()
{return Ok(_myOption);
}

启动程序，访问：https://localhost:5001/config/option

输出如下：

{"name":"Mingson","age":25}

通过 Get 的方式

myOption = Configuration.GetSection("MyOption").Get<MyOption>();

通过 Configure 绑定 Option

IOptions

• IOptions

  被注册为 singletone，不支持为可命名的配置

• IOptionsSnapshot

  被注册为 scoped，支持为可命名的配置

• IOptionsMonitor

  被注册为 singletone，会被通知，支持重载配置，支持为可命名的配置

IOptions

// 直接注入到容器中
services.Configure<MyOption>(Configuration.GetSection("MyOption"));

通过 IOptions 注入

public ConfigController(IConfiguration configuration, IOptions<MyOption> myOption)
{_configuration = configuration;_myOption = myOption.Value;
}

启动程序可以得到同样的输出

IOptionsSnapshot

public ConfigController(IConfiguration configuration, IOptionsSnapshot<MyOption> myOption)
{_configuration = configuration;_myOption = myOption.Value;
}

启动程序，修改配置，刷新浏览器，可以获取到修改后的配置

可命名的配置

appsettings.json

"Jack": {"Name": "Jack","Age": 16},"Peter": {"Name": "Peter","Age": 18}

MyOption.cs

public const string PETER = "Peter";public const string JACK = "Jack";

ConfigureServices

services.Configure<MyOption>("Peter", Configuration.GetSection("Peter"));
services.Configure<MyOption>("Jack", Configuration.GetSection("Jack"));

ConfigController

_myOption = myOption.Get(MyOption.PETER);
_myOption = myOption.Get(MyOption.JACK);

启动程序即可读取不同命名的配置

IOptionsMonitor

public ConfigController(IConfiguration configuration, IOptionsMonitor<MyOption> myOption)
{_configuration = configuration;_myOption = myOption.CurrentValue;// 配置变化处理myOption.OnChange(option =>{});
}

option 验证

属性验证标签

namespace HelloApi
{public class MyConfigOptions{public const string MyConfig = "MyConfig";[RegularExpression(@"^[a-zA-Z''-'\s]{1,40}$")]public string Key1 { get; set; }[Range(0, 1000, ErrorMessage = "Value for {0} must be between {1} and {2}.")]public int Key2 { get; set; }public int Key3 { get; set; }}
}

绑定后校验

ConfigureServices

services.AddOptions<MyOption>().Bind(Configuration.GetSection("MyOption")).ValidateDataAnnotations();

MyOption

[Range(1, 20)]
public int Age { get; set; }

启动程序，输出如下：

OptionsValidationException: DataAnnotation validation failed for members: 'Age' with the error: 'The field Age must be between 1 and 20.'.

PostConfigure

当配置被读取出来的时候会被执行

services.PostConfigure<MyOption>(option =>
{if (option.Age == 20){option.Age = 19;}
});

GitHub源码链接：

https://github.com/MINGSON666/Personal-Learning-Library/tree/main/ArchitectTrainingCamp/HelloApi

课程链接

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