簡單介紹,直接官方文檔

https://docs.microsoft.com/zh-cn/aspnet/core/fundamentals/dependency-injection?view=aspnetcore-2.2

public interface IOperation {Guid OperationId { get; } }public interface IOperationTransient : IOperation { }public interface IOperationScoped : IOperation { }public interface IOperationSingleton : IOperation { }public interface IOperationSingletonInstance : IOperation { } public class Operation : IOperationTransient, IOperationScoped, IOperationSingleton, IOperationSingletonInstance {public Operation() : this(Guid.NewGuid()){}public Operation(Guid id){OperationId = id;}public Guid OperationId { get; private set; } } public class OperationService {public OperationService(IOperationTransient transientOperation,IOperationScoped scopedOperation,IOperationSingleton singletonOperation,IOperationSingletonInstance instanceOperation){TransientOperation = transientOperation;ScopedOperation = scopedOperation;SingletonOperation = singletonOperation;SingletonInstanceOperation = instanceOperation;}public IOperationTransient TransientOperation { get; }public IOperationScoped ScopedOperation { get; }public IOperationSingleton SingletonOperation { get; }public IOperationSingletonInstance SingletonInstanceOperation { get; } } 在 Startup.ConfigureServices 中，根據(jù)其指定的生存期，將每個類型添加到容器中： C#public void ConfigureServices(IServiceCollection services) {services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);services.AddScoped<IMyDependency, MyDependency>();services.AddTransient<IOperationTransient, Operation>();services.AddScoped<IOperationScoped, Operation>();services.AddSingleton<IOperationSingleton, Operation>();services.AddSingleton<IOperationSingletonInstance>(new Operation(Guid.Empty));// OperationService depends on each of the other Operation types.services.AddTransient<OperationService, OperationService>(); } public class IndexModel : PageModel {private readonly IMyDependency _myDependency;public IndexModel(IMyDependency myDependency, OperationService operationService,IOperationTransient transientOperation,IOperationScoped scopedOperation,IOperationSingleton singletonOperation,IOperationSingletonInstance singletonInstanceOperation){_myDependency = myDependency;OperationService = operationService;TransientOperation = transientOperation;ScopedOperation = scopedOperation;SingletonOperation = singletonOperation;SingletonInstanceOperation = singletonInstanceOperation;}public OperationService OperationService { get; }public IOperationTransient TransientOperation { get; }public IOperationScoped ScopedOperation { get; }public IOperationSingleton SingletonOperation { get; }public IOperationSingletonInstance SingletonInstanceOperation { get; }public async Task OnGetAsync(){await _myDependency.WriteMessage("IndexModel.OnGetAsync created this message.");} }

以下兩個輸出顯示了兩個請求的結(jié)果：

第一個請求：

控制器操作：

暫時性：d233e165-f417-469b-a866-1cf1935d2518
作用域：5d997e2d-55f5-4a64-8388-51c4e3a1ad19
單一實例：01271bc1-9e31-48e7-8f7c-7261b040ded9
實例：00000000-0000-0000-0000-000000000000

OperationService?操作：

暫時性：c6b049eb-1318-4e31-90f1-eb2dd849ff64
作用域：5d997e2d-55f5-4a64-8388-51c4e3a1ad19
單一實例：01271bc1-9e31-48e7-8f7c-7261b040ded9
實例：00000000-0000-0000-0000-000000000000

第二個請求：

控制器操作：

暫時性：b63bd538-0a37-4ff1-90ba-081c5138dda0
作用域：31e820c5-4834-4d22-83fc-a60118acb9f4
單一實例：01271bc1-9e31-48e7-8f7c-7261b040ded9
實例：00000000-0000-0000-0000-000000000000

OperationService?操作：

暫時性：c4cbacb8-36a2-436d-81c8-8c1b78808aaf
作用域：31e820c5-4834-4d22-83fc-a60118acb9f4
單一實例：01271bc1-9e31-48e7-8f7c-7261b040ded9
實例：00000000-0000-0000-0000-000000000000

觀察哪個?OperationId?值會在一個請求之內(nèi)和不同請求之間變化：

• • 暫時性 對象始終不同。?第一個和第二個客戶端請求的暫時性?OperationId?值對于?OperationService?操作和在客戶端請求內(nèi)都是不同的。?為每個服務請求和客戶端請求提供了一個新實例。
  • 作用域 對象在一個客戶端請求中是相同的，但在多個客戶端請求中是不同的。
  • 單一實例 對象對每個對象和每個請求都是相同的（不管?Startup.ConfigureServices?中是否提供?Operation?實例）。

接下來是本文重點要說明的

?

public void ConfigureServices(IServiceCollection services) {services.AddSingleton<SingletonService>();services.AddTransient<TransientService>();services.AddScoped<ScopedService>(); }

?

public class SingletonService{public string Id = Guid.NewGuid().ToString();}public class ScopedService{public string Id = Guid.NewGuid().ToString();}public class TransientService{public string Id = Guid.NewGuid().ToString();private ScopedService _transient;private SingletonService _singleton;public TransientService(ScopedService transient, SingletonService singleton){_transient = transient;_singleton = singleton;}}

這種情況是可以的,transient 可以依賴 singleton 和 scoped

對于 Transient 服務,它可以被任何服務依賴,但是在依賴的服務中創(chuàng)建的服務的生命周期會跟隨依賴的服務
對于 Scoped 服務,它只能被 Transient 和 Scoped 服務依賴,生命周期不會變化,如果要在 Singleton 服務中使用,可以使用 IServiceProvider 的 CreateScope 方法 ,然后 GetService, 但是 生成的 scoped 服務生命周期為 Singleton
對于 Singleton 服務,它可以被任何服務依賴,生命周期不會變化 public class SingletonService{public string Id = Guid.NewGuid().ToString();private ScopedService _scoped;public SingletonService(IServiceProvider serviceProvider){using (var scope = serviceProvider.CreateScope()){_scoped = scope.ServiceProvider.GetService<ScopedService>();}}}public class ScopedService{public string Id = Guid.NewGuid().ToString();}public class TransientService{public string Id = Guid.NewGuid().ToString();}

?

這個 在單例中使用 Scoped 服務

轉(zhuǎn)載于:https://www.cnblogs.com/microestc/p/11215094.html

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