asp.net core 依賴註入問題

     最近.net core可以跨平臺了，這是一個偉大的事情，為了可以趕上兩年以後的跨平臺部署大潮，我也加入到了學習之列。今天研究的是依賴註入，但是我發現一個問題，困擾我很久，現在我貼出來，希望可以有人幫忙解決或回覆一下。

   背景：我測試.net自帶的依賴註入生命周期，一共三個：Transient、Scope、Single三種，通過一個GUID在界面展示，但是我發現scope和single的每次都是相同的，並且single實例的guid值每次都會改變。

通過截圖可以看到scope和Single每次瀏覽器刷新都會改變，scope改變可以理解，就是每次請求都會改變。但是single 每次都改變就不對了。應該保持一個唯一值才對。

Program.cs代碼：啟動代碼

 1 namespace CoreStudy
 2 {
 3     public class Program
 4     {
 5         public static void Main(string[] args)
 6         {
 7             Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
 8             var host = new WebHostBuilder()
 9                 .UseKestrel()//使用伺服器serve
10                 .UseContentRoot(Directory.GetCurrentDirectory())
11                 .UseIISIntegration()//使用IIS
12                 .UseStartup<Startup>()//使用起始頁
13                 .Build();//IWebHost
14 
15             host.Run();//構建用於宿主應用程式的IWebHost
16             //然後啟動它來監聽傳入的HTTP請求
17         }
18     }
19 }

Startup.cs 文件代碼

 1 namespace CoreStudy
 2 {
 3     public class Startup
 4     {
 5         public Startup(IHostingEnvironment env, ILoggerFactory logger)
 6         {
 7             var builder = new ConfigurationBuilder()
 8                 .SetBasePath(env.ContentRootPath)
 9                 .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
10                 .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
11                 .AddEnvironmentVariables();
12             builder.AddInMemoryCollection();
13 
14         }
15         // This method gets called by the runtime. Use this method to add services to the container.
16         // For more information on how to configure your application, visit http://go.microsoft.com/fwlink/?LinkID=398940
17         public void ConfigureServices(IServiceCollection services)
18         {//定義服務            
19             services.AddMvc();
20             services.AddLogging();
21             services.AddTransient<IPersonRepository, PersonRepository>();
22             services.AddTransient<IGuidTransientAppService, TransientAppService>();
23 
24             services.AddScoped<IGuidScopeAppService, ScopeAppService>();
25 
26             services.AddSingleton<IGuidSingleAppService, SingleAppService>();
27         }
28 
29         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
30         public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IApplicationLifetime appLifetime)
31         {//定義中間件
32 
33             if (env.IsDevelopment())
34             {
35                 app.UseDeveloperExceptionPage();
36                 app.UseBrowserLink();
37                 app.UseDatabaseErrorPage();
38 
39             }
40             else
41             {
42                 app.UseExceptionHandler("/Home/Error");
43             }
44             app.UseStaticFiles();
45             //app.UseStaticFiles(new StaticFileOptions() {
46             //      FileProvider=new PhysicalFileProvider(Path.Combine(Directory.GetCurrentDirectory(),@"staticFiles")),
47             //       RequestPath="/staticfiles"
48             // });
49             //預設路由設置
50             app.UseMvc(routes =>
51             {
52                 routes.MapRoute(name: "default", template: "{controller=Person}/{action=Index}/{id?}");
53             });
54 
55            
56         }
57     }
58 }

請註意22-26行，註冊了三種不同生命周期的實例，transientService、scopeService以及singleService。

對應的介面定義：

 1 namespace CoreStudy
 2 {
 3     public interface IGuideAppService
 4     {
 5         Guid GuidItem();
 6     }
 7     public interface IGuidTransientAppService:IGuideAppService
 8     { }
 9     public interface IGuidScopeAppService:IGuideAppService
10     { }
11     public interface IGuidSingleAppService:IGuideAppService
12     { }
13 
14 }
15 
16 namespace CoreStudy
17 {
18     public class GuidAppService : IGuideAppService
19     {
20         private readonly Guid item;
21         public GuidAppService()
22         {
23             item = Guid.NewGuid();
24         }
25         public Guid GuidItem()
26         {
27             return item;
28         }
29         
30     }
31     public class TransientAppService:GuidAppService,IGuidTransientAppService
32     {
33 
34     }
35 
36     public class ScopeAppService:GuidAppService,IGuidScopeAppService
37     { }
38     public class SingleAppService:GuidAppService,IGuidSingleAppService
39     { }
40 }

代碼很簡單，只是定義了三種不同實現類。

控制器中 通過構造函數註入方式註入：

 1 namespace CoreStudy.Controllers
 2 {
 3     /// <summary>
 4     /// 控制器方法
 5     /// </summary>
 6     public class PersonController : Controller
 7     {
 8         private readonly IGuidTransientAppService transientService;
 9         private readonly IGuidScopeAppService scopedService;
10         private readonly IGuidSingleAppService singleService;
11 
12 
13         private IPersonRepository personRepository = null;
14         /// <summary>
15         /// 構造函數
16         /// </summary>
17         /// <param name="repository"></param>
18         public PersonController(IGuidTransientAppService trsn, IGuidScopeAppService scope, IGuidSingleAppService single)
19         {
20             this.transientService = trsn;
21             this.scopedService = scope;
22             this.singleService = single;
23         }
24 
25         /// <summary>
26         /// 主頁方法
27         /// </summary>
28         /// <returns></returns>
29         public IActionResult Index()
30         {
31             ViewBag.TransientService = this.transientService.GuidItem();
32 
33             ViewBag.scopeService = this.scopedService.GuidItem();
34 
35             ViewBag.singleservice = this.scopedService.GuidItem();
36 
37             return View();
38         }
39 
40 
41     }
42 }

控制器對應的視圖文件Index.cshtm

 1 @{
 2     ViewData["Title"] = "Person Index";
 3     Layout = null;
 4 }
 5 
 6 <form asp-controller="person"  method="post" class="form-horizontal" role="form"> 
 7      <h4>創建賬戶</h4>
 8     <hr />
 9    <div class="row">
10        <div class="col-md-4">
11            <span>TransientService:</span>
12            @ViewBag.TransientService
13        </div>       
14    </div>
15     <div class="row">
16         <span>Scope</span>
17         @ViewBag.ScopeService
18     </div>
19     <div class="row">
20         <span>Single</span>
21         @ViewBag.SingleService
22     </div>
23     <div class="col-md-4">
24         @await Component.InvokeAsync("Greeting");
25     </div>
26 </form>

其他無關代碼就不粘貼了，希望各位能給個解釋，我再看一下代碼，是否哪裡需要特殊設置。

 答案在PersonController 類的 35行，此問題主要是為了能夠更好的理解依賴註入

.Net Core來了，我們又可以通過學習來漲工資了。