C# 从ConfigureServices内使用ASP.NET Core DI解析实例
如何使用ASP.NET Core MVC内置的依赖项注入框架手动解析类型 设置容器非常简单:C# 从ConfigureServices内使用ASP.NET Core DI解析实例,c#,dependency-injection,asp.net-core,asp.net-core-mvc,C#,Dependency Injection,Asp.net Core,Asp.net Core Mvc,如何使用ASP.NET Core MVC内置的依赖项注入框架手动解析类型 设置容器非常简单: public void ConfigureServices(IServiceCollection services) { // ... services.AddTransient<ISomeService, SomeConcreteService>(); } IServiceCollection中没有此类方法手动解析实例涉及使用以下接口: 正在解析Startup.Conf
public void ConfigureServices(IServiceCollection services)
{
// ...
services.AddTransient<ISomeService, SomeConcreteService>();
}
IServiceCollection
中没有此类方法手动解析实例涉及使用以下接口:
正在解析Startup.ConfigureServices中的依赖项
解析控制器操作中的依赖项
该接口用于构建依赖项注入容器。在完全构建之后,它将被组合成一个实例,您可以使用它来解析服务。您可以将IServiceProvider
注入任何类。iaapplicationbuilder
和HttpContext
类也可以通过各自的or属性提供服务提供者
IServiceProvider
定义解析服务的方法:
var service = (IFooService)serviceProvider.GetService(typeof(IFooService));
还有几种方便的扩展方法可用,例如(为Microsoft.Extensions.DependencyInjection
使用添加)
解析startup类内的服务
注入依赖项
运行时的宿主服务提供程序可以将某些服务注入启动
类的构造函数中,例如,
(IHostingEnvironment
在3.0之前的版本中)和iSeries提供程序
。请注意,后者是由宿主层构建的实例,仅包含启动应用程序的基本服务
ConfigureServices()
方法不允许注入服务,它只接受IServiceCollection
参数。这很有意义,因为ConfigureServices()
是注册应用程序所需服务的地方。但是,您可以在此处使用在启动的构造函数中注入的服务,例如:
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
public void ConfigureServices(IServiceCollection services)
{
// Use Configuration here
}
services.AddTransient<ITestService, TestService>();
然后可以将在ConfigureServices()
中注册的任何服务注入Configure()
方法;您可以在iaapplicationbuilder
参数之后添加任意数量的服务:
public void ConfigureServices(IServiceCollection services)
{
services.AddScoped<IFooService>();
}
public void Configure(IApplicationBuilder app, IFooService fooService)
{
fooService.Bar();
}
可以在启动
类的构造函数中传递并直接使用IServiceProvider
,但如上所述,它将包含有限的服务子集,因此效用有限:
public Startup(IServiceProvider serviceProvider)
{
var hostingEnv = serviceProvider.GetService<IWebHostEnvironment>();
}
请注意:
通常,您应该避免在ConfigureServices()
方法中解析服务,因为这实际上是您配置应用程序服务的地方。有时您只需要访问IOptions
实例。您可以通过将IConfiguration
实例中的值绑定到MyOptions
的实例来实现这一点(这基本上就是选项框架所做的):
或者对AddSingleton/AddScoped/AddTransient
使用重载:
// Works for AddScoped and AddTransient as well
services.AddSingleton<IBarService>(sp =>
{
var fooService = sp.GetRequiredService<IFooService>();
return new BarService(fooService);
}
//也适用于addScope和AddTransient
services.AddSingleton(sp=>
{
var fooService=sp.GetRequiredService();
返回新的BarService(fooService);
}
手动解析服务(又称服务定位器)是。虽然它有它的用例(对于框架和/或基础结构层),但您应该尽可能避免它。如果您使用模板生成应用程序,则在启动
类中会有类似的内容:
public void ConfigureServices(IServiceCollection services)
{
// Add framework services.
services.AddApplicationInsightsTelemetry(Configuration);
services.AddMvc();
}
然后可以在此处添加依赖项,例如:
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
public void ConfigureServices(IServiceCollection services)
{
// Use Configuration here
}
services.AddTransient<ITestService, TestService>();
然后,您可以解析您添加的服务:
var service = serviceProvider.GetService<ITestService>();
ITestService.cs
public interface ITestService
{
int GenerateRandom();
}
public class TestService : ITestService
{
public int GenerateRandom()
{
return 4;
}
}
TestService.cs
public interface ITestService
{
int GenerateRandom();
}
public class TestService : ITestService
{
public int GenerateRandom()
{
return 4;
}
}
Startup.cs(配置服务)
public void配置服务(IServiceCollection服务)
{
services.AddApplicationInsightsTelemetry(配置);
services.AddMvc();
services.AddTransient();
}
HomeController.cs
using Microsoft.Extensions.DependencyInjection;
namespace Core.Controllers
{
public class HomeController : Controller
{
public HomeController(IServiceProvider serviceProvider)
{
var service = serviceProvider.GetService<ITestService>();
int rnd = service.GenerateRandom();
}
使用Microsoft.Extensions.DependencyInjection;
名称空间核心控制器
{
公共类HomeController:控制器
{
公共家庭控制器(IServiceProvider服务提供商)
{
var service=serviceProvider.GetService();
int rnd=service.generateradom();
}
公共void配置服务(IServiceCollection服务)
{
services.AddMvc();
services.AddDbContext(选项=>
options.UseSqlServer(Configuration.GetConnectionString(“SqlConnectionString”));
services.addScope();
services.addScope();
}
您可以通过这种方式在属性(如AuthorizeAttribute)中注入依赖项
var someservice = (ISomeService)context.HttpContext.RequestServices.GetService(typeof(ISomeService));
public void Configure(IApplicationBuilder app)
{
//---------- Your code
using (var serviceScope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>().CreateScope())
{
var resultLogic = serviceScope.ServiceProvider.GetService<IResultLogic>();
resultLogic.YourMethod();
}
//---------- Your code
}
如果您只需要解析一个依赖项,以便将其传递给正在注册的另一个依赖项的构造函数,那么您可以这样做
假设您有一个包含字符串和等距服务的服务
public class AnotherService : IAnotherService
{
public AnotherService(ISomeService someService, string serviceUrl)
{
...
}
}
在Startup.cs中注册此文件时,需要执行以下操作:
ISomeService service = services.Resolve<ISomeService>();
services.AddScoped<IAnotherService>(ctx =>
new AnotherService(ctx.GetService<ISomeService>(), "https://someservice.com/")
);
services.AddScoped(ctx=>
新建另一个服务(ctx.GetService(),”https://someservice.com/")
);
我知道这是一个老问题,但我很惊讶这里没有一个相当明显和令人厌恶的黑客
您可以利用定义自己的ctor函数的能力,在定义服务时从服务中获取必要的值……显然,这将在每次请求服务时运行,除非您在第一次构造ctor时明确删除/清除并重新添加此服务的定义
此方法的优点是不需要您在配置服务期间构建或使用服务树。您仍在定义如何配置服务
public void ConfigureServices(IServiceCollection services)
{
//Prey this doesn't get GC'd or promote to a static class var
string? somevalue = null;
services.AddSingleton<IServiceINeedToUse, ServiceINeedToUse>(scope => {
//create service you need
var service = new ServiceINeedToUse(scope.GetService<IDependantService>())
//get the values you need
somevalue = somevalue ?? service.MyDirtyHack();
//return the instance
return service;
});
services.AddTransient<IOtherService, OtherService>(scope => {
//Explicitly ensuring the ctor function above is called, and also showcasing why this is an anti-pattern.
scope.GetService<IServiceINeedToUse>();
//TODO: Clean up both the IServiceINeedToUse and IOtherService configuration here, then somehow rebuild the service tree.
//Wow!
return new OtherService(somevalue);
});
}
public void配置服务(IServiceCollection服务)
{
//这不会得到GC'd或提升为静态类var
字符串?somevalue=null;
services.AddSingleton(范围=>{
//创建您需要的服务
var service=new ServiceINeedToUse(scope.GetService())
//获取所需的值
somevalue=somevalue??service.MyDirtyHack();
//归还仪器
public void ConfigureServices(IServiceCollection services)
{
services.AddApplicationInsightsTelemetry(Configuration);
services.AddMvc();
services.AddTransient<ITestService, TestService>();
}
using Microsoft.Extensions.DependencyInjection;
namespace Core.Controllers
{
public class HomeController : Controller
{
public HomeController(IServiceProvider serviceProvider)
{
var service = serviceProvider.GetService<ITestService>();
int rnd = service.GenerateRandom();
}
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();
services.AddDbContext<ConfigurationRepository>(options =>
options.UseSqlServer(Configuration.GetConnectionString("SqlConnectionString")));
services.AddScoped<IConfigurationBL, ConfigurationBL>();
services.AddScoped<IConfigurationRepository, ConfigurationRepository>();
}
var someservice = (ISomeService)context.HttpContext.RequestServices.GetService(typeof(ISomeService));
public class AnotherService : IAnotherService
{
public AnotherService(ISomeService someService, string serviceUrl)
{
...
}
}
services.AddScoped<IAnotherService>(ctx =>
new AnotherService(ctx.GetService<ISomeService>(), "https://someservice.com/")
);
public void ConfigureServices(IServiceCollection services)
{
//Prey this doesn't get GC'd or promote to a static class var
string? somevalue = null;
services.AddSingleton<IServiceINeedToUse, ServiceINeedToUse>(scope => {
//create service you need
var service = new ServiceINeedToUse(scope.GetService<IDependantService>())
//get the values you need
somevalue = somevalue ?? service.MyDirtyHack();
//return the instance
return service;
});
services.AddTransient<IOtherService, OtherService>(scope => {
//Explicitly ensuring the ctor function above is called, and also showcasing why this is an anti-pattern.
scope.GetService<IServiceINeedToUse>();
//TODO: Clean up both the IServiceINeedToUse and IOtherService configuration here, then somehow rebuild the service tree.
//Wow!
return new OtherService(somevalue);
});
}
public void Configure(IApplicationBuilder app)
{
//---------- Your code
using (var serviceScope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>().CreateScope())
{
var resultLogic = serviceScope.ServiceProvider.GetService<IResultLogic>();
resultLogic.YourMethod();
}
//---------- Your code
}