獲取ASP.NET Core中全部注入(DI)服務，在ASP.NET Core中加入了Dependency Injection依賴注入。html
咱們在Controller，或者在ASP.NET Core程序中的其餘地方使用注入的服務，如logging 等。git
咱們要怎樣獲取ASP.NET Core中全部注入(DI)服務呢，下面咱們來一探究竟， 也能夠來看看ASP.NET Core到底注入了哪些服務。github
依賴注入簡單介紹：app
依賴注入（Dependency injection , DI）是一種實現對象及其合做者或依賴項之間鬆散耦合的技術。將類用來執行其操做的這些對象以某種方式提供給該類，而不是直接實例化合做者或使用靜態引用。asp.net
咱們新建一個ASP.NET Core 空應用程序。async
而後Startup 中定義一個變量 private IServiceCollection _services;post
public class Startup
{
private IServiceCollection _services;
// 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)
{
_services = services;
}
// 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)
{
loggerFactory.AddConsole();
var _logger = loggerFactory.CreateLogger("Services");
_logger.LogInformation($"Total Services Registered: {_services.Count}");
foreach (var service in _services)
{
_logger.LogInformation($"Service: {service.ServiceType.FullName}\n Lifetime: {service.Lifetime}\n Instance: {service.ImplementationType?.FullName}");
}
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
app.Run(async (context) =>
{
await context.Response.WriteAsync("Hello World!");
});
}
}
在 Configure 中使用Logger打印出來。ui
執行程序，能夠看到，默認有14個服務。this
而後咱們也能夠將這些服務在網頁中展現出來。spa
咱們在 Configure 中加入以下代碼：
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
loggerFactory.AddConsole();
var _logger = loggerFactory.CreateLogger("Services");
_logger.LogInformation($"Total Services Registered: {_services.Count}");
foreach (var service in _services)
{
_logger.LogInformation($"Service: {service.ServiceType.FullName}\n Lifetime: {service.Lifetime}\n Instance: {service.ImplementationType?.FullName}");
}
if (env.IsDevelopment())
{
app.Map("/allservices", builder => builder.Run(async context =>
{
context.Response.ContentType = "text/html; charset=utf-8";
await context.Response.WriteAsync($"<h1>全部服務{_services.Count}個</h1><table><thead><tr><th>類型</th><th>生命週期</th><th>Instance</th></tr></thead><tbody>");
foreach (var svc in _services)
{
await context.Response.WriteAsync("<tr>");
await context.Response.WriteAsync($"<td>{svc.ServiceType.FullName}</td>");
await context.Response.WriteAsync($"<td>{svc.Lifetime}</td>");
await context.Response.WriteAsync($"<td>{svc.ImplementationType?.FullName}</td>");
await context.Response.WriteAsync("</tr>");
}
await context.Response.WriteAsync("</tbody></table>");
}));
app.UseDeveloperExceptionPage();
}
app.Run(async (context) =>
{
await context.Response.WriteAsync("Hello World!");
});
}
而後咱們使用自宿主的方式執行，在地址欄輸入 http://localhost:5000/allservices
一樣能夠看到14個服務，這裏我將/allservices 放在 Development 環境下，只有在程序調試時才能看到，運行是不行的。
咱們在項目添加 Microsoft.AspNetCore.Mvc.Core 的引用 。
而後在 ConfigureServices 中加入
public void ConfigureServices(IServiceCollection services)
{
services.AddMvcCore();//添加MvcCore
_services = services;
}
咱們就能夠看到MvcCore 裏多加註入的服務
http://localhost:5000/allservices
能夠看到增長不少的服務。咱們也能夠添加其餘的，而後查看注入了哪些服務。
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