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试用.Net8

· 4分钟阅读

环境​

  • dotnet
❯ dotnet --list-sdks
7.0.400 [C:\Program Files\dotnet\sdk]
8.0.100-preview.7.23376.3 [C:\Program Files\dotnet\sdk]
  • Microsoft Visual Studio Professional 2022 (64-bit) - Current Version 17.7.2

准备​

目前.net8还是preview状态，需要在VS中开启，否则无法选用.net8版本的SDK。

Sample​

Kx.Toolx.Clicky.csproj
<Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
        <Nullable>enable</Nullable>

        <!-- AOT -->
        <PublishAot>true</PublishAot>
        <IsAotCompatible>true</IsAotCompatible>
        <InvariantGlobalization>true</InvariantGlobalization>

        <!-- NuGet -->
        <PackAsTool>true</PackAsTool>
        <ToolCommandName>clicky</ToolCommandName>
        <RootNamespace>Kx.Toolx.Clicky</RootNamespace>
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="Microsoft.Extensions.Hosting" Version="8.0.0-preview.7.23375.6" />
        <PackageReference Include="Serilog.Extensions.Logging" Version="7.0.0" />
        <PackageReference Include="Serilog.Sinks.Console" Version="4.2.0-dev-00918" />
        <PackageReference Include="Microsoft.Windows.CsWin32" Version="0.3.18-beta">
            <PrivateAssets>all</PrivateAssets>
            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
        </PackageReference>
    </ItemGroup>

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

</Project>

选项模式的简易替代方案​

直接使用选项模式会报警告：

原因是Configure方法已经标了RequiresDynamicCode特性：

        [RequiresDynamicCode(OptionsBuilderConfigurationExtensions.RequiresDynamicCodeMessage)]
        [RequiresUnreferencedCode(OptionsBuilderConfigurationExtensions.TrimmingRequiredUnreferencedCodeMessage)]
        public static IServiceCollection Configure<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] TOptions>(this IServiceCollection services, IConfiguration config) where TOptions : class
            => services.Configure<TOptions>(Options.Options.DefaultName, config);

跟进代码后发现核心代码如下：

        [RequiresDynamicCode(OptionsBuilderConfigurationExtensions.RequiresDynamicCodeMessage)]
        [RequiresUnreferencedCode(OptionsBuilderConfigurationExtensions.TrimmingRequiredUnreferencedCodeMessage)]
        public static IServiceCollection Configure<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] TOptions>(this IServiceCollection services, string? name, IConfiguration config, Action<BinderOptions>? configureBinder)
            where TOptions : class
        {
            ThrowHelper.ThrowIfNull(services);
            ThrowHelper.ThrowIfNull(config);

            services.AddOptions();
            services.AddSingleton<IOptionsChangeTokenSource<TOptions>>(new ConfigurationChangeTokenSource<TOptions>(name, config));
            return services.AddSingleton<IConfigureOptions<TOptions>>(new NamedConfigureFromConfigurationOptions<TOptions>(name, config, configureBinder));
        }

真正受影响的是NamedConfigureFromConfigurationOptions这个类：

        [RequiresDynamicCode(OptionsBuilderConfigurationExtensions.RequiresDynamicCodeMessage)]
        [RequiresUnreferencedCode(OptionsBuilderConfigurationExtensions.TrimmingRequiredUnreferencedCodeMessage)]
        public NamedConfigureFromConfigurationOptions(string? name, IConfiguration config, Action<BinderOptions>? configureBinder)
            : base(name, options => config.Bind(options, configureBinder))
        {
            ThrowHelper.ThrowIfNull(config);
        }

其核心作用是将config中的配置信息填充给被注入的options对象。

我们做如下替换：

  1. 初始化

    await Host.CreateDefaultBuilder(args)
        .ConfigureServices((hostContext, services) =>
        {
            // 服务注册
            services.AddHostedService<HostedService>();

            // Options
            
            // 原配置
            // services.Configure<ClickyConfig>(hostContext.Configuration.GetSection(ClickyConfig.KEY));

            // 替换后
            services.AddOptions();
            var config = hostContext.Configuration.GetSection(ClickyConfig.KEY);
            services.AddSingleton<IOptionsChangeTokenSource<ClickyConfig>>(new ConfigurationChangeTokenSource<ClickyConfig>(string.Empty, config));
            // 使用 ClickyConfigureNamedOptions 替换 NamedConfigureFromConfigurationOptions
            services.AddSingleton<IConfigureOptions<ClickyConfig>>(new ClickyConfigureNamedOptions(string.Empty, config));
        })
        .UseConsoleLifetime()
        .Build()
        .RunAsync()
        ;
  1. ClickyConfigureNamedOptions
using System.Drawing;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Options;

namespace Kx.Toolx.Clicky;

internal class ClickyConfigureNamedOptions : ConfigureNamedOptions<ClickyConfig>
{
    public ClickyConfigureNamedOptions(string? name, IConfiguration configuration)
        : base(name, cc => Bind(cc, configuration))
    {
    }

    private static void Bind(ClickyConfig config, IConfiguration configuration)
    {
        if (config == null)
        {
            return;
        }

        if (configuration == null)
        {
            return;
        }

        // 填充config的具体字段
        config.Hwnd = configuration[nameof(config.Hwnd)] ?? string.Empty;
        config.TimerPeriod = double.TryParse(configuration[nameof(config.TimerPeriod)], out var tp) ? tp : 5;
        config.Points = configuration.GetSection(nameof(config.Points))
            .GetChildren()
            .Select(p => new Point((int.TryParse(p["X"], out var x) ? x : 0), (int.TryParse(p["Y"], out var y) ? y : 0)))
            .ToList()
            ;
    }
}

相当于手动解析了一下配置，目前项目配置不复杂还可以接受，复杂的话就够呛。

不过我相信官方不久就应该要解决这个问题了，毕竟选型模式挺好用且挺好用的。躺着等就好。

参考​