asp.net core 依赖注入问题

     最近.net core可以跨平台了，这是一个伟大的事情，为了可以赶上两年以后的跨平台部署大潮，我也加入到了学习之列。今天研究的是依赖注入，但是我发现一个问题，困扰我很久，现在我贴出来，希望可以有人帮忙解决或回复一下。

   背景：我测试.net自带的依赖注入生命周期，一共三个：Transient、Scope、Single三种，通过一个GUID在界面展示，但是我发现scope和single的每次都是相同的，并且single实例的guid值每次都会改变。

通过截图可以看到scope和Single每次浏览器刷新都会改变，scope改变可以理解，就是每次请求都会改变。但是single 每次都改变就不对了。应该保持一个唯一值才对。

 

Program.cs代码：启动代码

namespace CoreStudy
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
            var host = new WebHostBuilder()
                .UseKestrel()//使用服务器serve
                .UseContentRoot(Directory.GetCurrentDirectory())
                .UseIISIntegration()//使用IIS
                .UseStartup<Startup>()//使用起始页
                .Build();//IWebHost

            host.Run();//构建用于宿主应用程序的IWebHost
            //然后启动它来监听传入的HTTP请求
        }
    }
}

Startup.cs 文件代码

namespace CoreStudy
{
    public class Startup
    {
        public Startup(IHostingEnvironment env, ILoggerFactory logger)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                .AddEnvironmentVariables();
            builder.AddInMemoryCollection();

        }
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit http://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {//定义服务            
            services.AddMvc();
            services.AddLogging();
            services.AddTransient<IPersonRepository, PersonRepository>();
            services.AddTransient<IGuidTransientAppService, TransientAppService>();

            services.AddScoped<IGuidScopeAppService, ScopeAppService>();

            services.AddSingleton<IGuidSingleAppService, SingleAppService>();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IApplicationLifetime appLifetime)
        {//定义中间件

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseBrowserLink();
                app.UseDatabaseErrorPage();

            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }
            app.UseStaticFiles();
            //app.UseStaticFiles(new StaticFileOptions() {
            //      FileProvider=new PhysicalFileProvider(Path.Combine(Directory.GetCurrentDirectory(),@"staticFiles")),
            //       RequestPath="/staticfiles"
            // });
            //默认路由设置
            app.UseMvc(routes =>
            {
                routes.MapRoute(name: "default", template: "{controller=Person}/{action=Index}/{id?}");
            });

           
        }
    }
}

请注意22-26行，注册了三种不同生命周期的实例，transientService、scopeService以及singleService。

对应的接口定义：

namespace CoreStudy
{
    public interface IGuideAppService
    {
        Guid GuidItem();
    }
    public interface IGuidTransientAppService:IGuideAppService
    { }
    public interface IGuidScopeAppService:IGuideAppService
    { }
    public interface IGuidSingleAppService:IGuideAppService
    { }

}

namespace CoreStudy
{
    public class GuidAppService : IGuideAppService
    {
        private readonly Guid item;
        public GuidAppService()
        {
            item = Guid.NewGuid();
        }
        public Guid GuidItem()
        {
            return item;
        }
        
    }
    public class TransientAppService:GuidAppService,IGuidTransientAppService
    {

    }

    public class ScopeAppService:GuidAppService,IGuidScopeAppService
    { }
    public class SingleAppService:GuidAppService,IGuidSingleAppService
    { }
}

代码很简单，只是定义了三种不同实现类。

控制器中 通过构造函数注入方式注入：

namespace CoreStudy.Controllers
{
    /// <summary>
    /// 控制器方法
    /// </summary>
    public class PersonController : Controller
    {
        private readonly IGuidTransientAppService transientService;
        private readonly IGuidScopeAppService scopedService;
        private readonly IGuidSingleAppService singleService;


        private IPersonRepository personRepository = null;
        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="repository"></param>
        public PersonController(IGuidTransientAppService trsn, IGuidScopeAppService scope, IGuidSingleAppService single)
        {
            this.transientService = trsn;
            this.scopedService = scope;
            this.singleService = single;
        }

        /// <summary>
        /// 主页方法
        /// </summary>
        /// <returns></returns>
        public IActionResult Index()
        {
            ViewBag.TransientService = this.transientService.GuidItem();

            ViewBag.scopeService = this.scopedService.GuidItem();

            ViewBag.singleservice = this.scopedService.GuidItem();

            return View();
        }


    }
}

控制器对应的视图文件Index.cshtm

@{
    ViewData["Title"] = "Person Index";
    Layout = null;
}

<form asp-controller="person"  method="post" class="form-horizontal" role="form"> 
     <h4>创建账户</h4>
    <hr />
   <div class="row">
       <div class="col-md-4">
           <span>TransientService:</span>
           @ViewBag.TransientService
       </div>       
   </div>
    <div class="row">
        <span>Scope</span>
        @ViewBag.ScopeService
    </div>
    <div class="row">
        <span>Single</span>
        @ViewBag.SingleService
    </div>
    <div class="col-md-4">
        @await Component.InvokeAsync("Greeting");
    </div>
</form>

 

其他无关代码就不粘贴了，希望各位能给个解释，我再看一下代码，是否哪里需要特殊设置。

 答案在PersonController 类的 35行，此问题主要是为了能够更好的理解依赖注入

.Net Core来了，我们又可以通过学习来涨工资了。