如何在.NET Core中使用默认依赖注入从父级创建子作用域？

Question

我正在构建一个控制台.NET Core应用程序.它会定期运行一个可以完成某些工作的方法.如何使ServiceProvider的行为与ASP.NET Core应用程序中的行为相同.我希望它在方法开始执行时解析作用域服务,并在方法结束时处理已解析的服务.

// pseudocode

globalProvider.AddScoped<ExampleService>();

// ...

using (var scopedProvider = globalProvider.CreateChildScope())
{
    var exampleService = scopedProvider.Resolve<ExampleService>();
}

Answer 1

引用Microsoft.Extensions.DependencyInjection包并创建范围:

var services = new ServiceCollection();
services.AddScoped<ExampleService>();
var globalProvider = services.BuildServiceProvider();

using (var scope = globalProvider.CreateScope())
{
    var localScoped = scope.ServiceProvider.GetService<ExampleService>();

    var globalScoped = globalProvider.GetService<ExampleService>();
}

您也可以轻松测试它:

using (var scope = globalProvider.CreateScope())
{
    var localScopedV1 = scope.ServiceProvider.GetService<ExampleService>();
    var localScopedV2 = scope.ServiceProvider.GetService<ExampleService>();
    Assert.Equal(localScopedV1, localScopedV2);

    var globalScoped = globalProvider.GetService<ExampleService>();
    Assert.NotEqual(localScopedV1, globalScoped);
    Assert.NotEqual(localScopedV2, globalScoped);
}

文档:服务生命周期和注册选项.