.NET10中通过appsettings.json配置文件获取信息的几个方法

 

{
  "AppSettings": {
    "Name": "配置系统实战应用",
    "Version": "1.0.0",
    "MaxItems": 100
  },
  "ConnectionStrings": {
    "DefaultConnection": "Server=localhost;Database=SampleDb;Trusted_Connection=True;"
  }
}

方法1 基于Host.CreateApplicationBuilder

 using Microsoft.Extensions.Hosting;
 var builder = Host.CreateApplicationBuilder(args);
 var env = builder.Environment;
 Console.WriteLine($"当前环境: {env.EnvironmentName}");
 Console.WriteLine($"输出Name：{builder.Configuration["AppSettings:Name"]}");

这个用法简单，直接支持命令行传参  dotnet run --environment Production，暂时不知道如何绑定到强类型类。

方法2 基于ConfigurationBuilder

var config = new ConfigurationBuilder()
    .SetBasePath(Directory.GetCurrentDirectory())
    .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
    .Build();

Console.WriteLine($"AppSettings.Name:{config["AppSettings:Name"]}");
Console.WriteLine($"AppSettings.Name1:{config["AppSettings:Name1"]}");

方法3 添加配置到Service容器，让后续可以通过DI注入到类中使用

AppSettings.cs文件中

 

    internal class AppSettingsService
    {
        private readonly AppSettings _options;
        public AppSettingsService(IOptions<AppSettings> options) { 
        _options = options.Value;
        }
        public void Show()
        {
            Console.WriteLine($"AppSettings.Name:{_options.Name}");
            Console.WriteLine($"AppSettings.Version:{_options.Version}");
            Console.WriteLine($"AppSettings.MaxItems:{_options.MaxItems}");
        }
    }

 

    internal class AppSettings
    {
        [Required(ErrorMessage ="Name值不能为空！")]
        public string Name { get; set; }
        public string Version { get; set; }
        public int MaxItems { get; set; }
    }

 这里的serviceCollection.Configure如果要正常使用需要安装包Microsoft.Extensions.Options.ConfigurationExtension

var serviceCollection = new ServiceCollection();
serviceCollection.Configure<AppSettings>(options =>
{
    config.GetSection("AppSettings")
    .Bind(options);
});
serviceCollection.AddSingleton<AppSettingsService>();
var serviceProvider = serviceCollection.BuildServiceProvider();

try
{
    var s = serviceProvider.GetService<AppSettingsService>();
    s.Show();
}
catch (Exception e)
{
    Console.WriteLine(e.Message);
}

 方法4 AddOptions并增加数据验证

serviceCollection.AddOptions<AppSettings>()
    .Bind(config.GetSection("AppSettings"))
    //这一步需要引入Microsoft.Extensions.Options.DataAnnotations包才能正常使用
    .ValidateDataAnnotations()
    .ValidateOnStart();

方法5 AddOptionsWithValidateOnStart并增加数据验证

serviceCollection
    .AddOptionsWithValidateOnStart<AppSettings>()
    .Bind(config.GetSection("AppSettings"))
    //这一步需要引入Microsoft.Extensions.Options.DataAnnotations包才能正常使用
    .ValidateDataAnnotations();

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net10.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Extensions.Configuration" Version="10.0.5" />
    <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="10.0.5" />
    <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="10.0.5" />
    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="10.0.5" />
    <PackageReference Include="Microsoft.Extensions.Hosting" Version="10.0.5" />
    <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="10.0.5" />
    <PackageReference Include="Microsoft.Extensions.Options.DataAnnotations" Version="10.0.5" />
  </ItemGroup>

  <ItemGroup>
    <None Update="appsettings.Production.json">
      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
    </None>
    <None Update="appsettings.json">
      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
    </None>
  </ItemGroup>

</Project>

如果有代码报错，看看是否缺少引用，比如说引入Json文件需要

Microsoft.Extensions.Configuration.Json，前面也有部分备注，多调试。