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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