1.前言 在ConfigureServices方法中的容器注册每个应用程序的服务，Asp.Core都可以为每个应用程序提供三种服务生命周期： Transient（暂时）：每次请求都会
在ConfigureServices方法中的容器注册每个应用程序的服务，Asp.Core都可以为每个应用程序提供三种服务生命周期：
为了演示生命周期和注册选项之间的差异，请考虑以下接口，将任务表示为具有唯一标识符 OperationId 的操作。根据以下接口配置操作服务的生命周期的方式，容器在类请求时提供相同或不同的服务实例：
public interface IOperation
{
Guid OperationId { get; }
}
public interface IOperationTransient : IOperation
{
}
public interface IOperationScoped : IOperation
{
}
public interface IOperationSingleton : IOperation
{
}
public interface IOperationSingletonInstance : IOperation
{
}上面四种服务接口在 Operation 类中实现。调用Operation类时将自动生成一个GUID，下面是Operation类的实现：
public class Operation : IOperationTransient, IOperationScoped, IOperationSingleton, IOperationSingletonInstance
{
public Operation() : this(Guid.NewGuid())
{
}
public Operation(Guid id)
{
OperationId = id;
}
public Guid OperationId { get; private set; }
}再注册一个OperationService服务实例，当通过依赖关系注入请求 OperationService 实例时，它将接收每个服务的新实例或基于从属服务（Operation）的生命周期的现有实例。OperationService 服务作用就是第二次调用 Operation类，查看Operation类实例的作用域变化。
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; }
}然后在Startup.ConfigureServices()服务容器中注册各个生命周期的实例：
public void ConfigureServices(IServiceCollection services)
{
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>();
}再在IndexModel模块里面调用OnGet方法输出，观察IOperation与OperationService类属性OperationId 值的变化：
public class IndexModel : PageModel
{
public OperationService _operationService { get; }
public IOperationTransient _transientOperation { get; }
public IOperationScoped _scopedOperation { get; }
public IOperationSingleton _singletonOperation { get; }
public IOperationSingletonInstance _singletonInstanceOperation { get; }
public IndexModel(
OperationService operationService,
IOperationTransient transientOperation,
IOperationScoped scopedOperation,
IOperationSingleton singletonOperation,
IOperationSingletonInstance singletonInstanceOperation)
{
_operationService = operationService;
_transientOperation = transientOperation;
_scopedOperation = scopedOperation;
_singletonOperation = singletonOperation;
_singletonInstanceOperation = singletonInstanceOperation;
}
public void OnGet()
{
Console.WriteLine("IOperation操作:");
Console.WriteLine("暂时:" + _transientOperation.OperationId.ToString());
Console.WriteLine("作用域:" + _scopedOperation.OperationId.ToString());
Console.WriteLine("单例:" + _singletonOperation.OperationId.ToString());
Console.WriteLine("实例:" + _singletonInstanceOperation.OperationId.ToString());
Console.WriteLine("OperationService操作:");
Console.WriteLine("暂时:" + _operationService._transientOperation.OperationId.ToString());
Console.WriteLine("作用域:" + _operationService._scopedOperation.OperationId.ToString());
Console.WriteLine("单例:" + _operationService._singletonOperation.OperationId.ToString());
Console.WriteLine("实例:" + _operationService._singletonInstanceOperation.OperationId.ToString());
}
}执行IndexModel 类输出结果：
由图总结如下：
2.1 Transient（暂时）：每次调用服务的时候都会创建一个新的实例。即在IndexModel类的局部方法或属性中（这里是OnGet方法）实例化一个依赖对象Operation类，伪代码是：
public class IndexModel: PageModel
{
public void OnGet()
{
//调用IndexModel类时，实例化了两次Operation类
//第一次
OperationService operationService=new OperationService();
//第二次
IOperationTransient TransientOperation=new Operation();
}
}2.2 Scoped（作用域）：一次请求（Action）内对象实例是相同的，但每次请求会产生一个新实例。相当于在IndexModel类的全局中实例化一次依赖对象Operation类，伪代码是：
OperationService operationService = null;
public IndexModel()
{
operationService = new OperationService();
operationService._scopedOperation = new Operation();
}
public void OnGet()
{
operationService._scopedOperation.OperationId;
IOperationScoped operationScoped = operationService._scopedOperation;
operationScoped.OperationId
}2.3 Singleton（单例）：首次请求初始化同一个实例，后续每次请求都使用同一个实例。相当于在整个应用Application中只实例化一次实例，常见的单例模式。
生命周期流程图如下：
到此这篇关于ASP.net core服务生命周期的文章就介绍到这了。希望对大家的学习有所帮助，也希望大家多多支持编程网。
--结束END--
本文标题: ASP.NETCore服务生命周期
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