目录

一：什么是IOC容器

二：简单理解内置Ioc容器

三：依赖注入内置Ioc容器

四：生命周期

五：多种注册方式

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一：什么是IOC容器

IOC容器是Inversion Of Control的缩写，翻译的意思就是控制反转。

DI依赖注入是Dependency Injection的缩写，翻译的意思就是依赖注入。

通过抽象【接口、抽象类、普通父类】获取具体的实例。

Ioc容器是创建对象并给对象中的属性赋值交由工厂管理，达到控制反转的目的。再通过DI依赖注入让工厂来管理对象的创建和属性的赋值。

Ioc容器的优点：实现组件之间的解耦，提高程序的灵活性、扩展性和可维护性。

DI依赖注入目前只支持构造函数注入，属性注入和方法注入请使用Autofac或其他第三方容器。

二：简单理解内置Ioc容器

using Microsoft.Extensions.DependencyInjection;
using System;namespace Study_ASP.NET_Core_MVC.ConsoleApp
{public static class Program{public static void Main(string[] args){//内置容器//1：Nuget引入Microsoft.Extensions.DependencyInjection.Abstractions//2：创建容器并初始化ServiceCollection serviceCollection = new ServiceCollection();//3：注册抽象和具体和普通类之间的关系serviceCollection.AddTransient<IPhone, ApplePhone>();//4：serviceCollection.Build一下ServiceProvider serviceProvider = serviceCollection.BuildServiceProvider();//5：获取对象的实例IPhone iPhone = serviceProvider.GetService<IPhone>();//6：内置容器调用方法iPhone.Call();iPhone.Text();Console.ReadLine();}}/// <summary>/// Interfaces层/// </summary>public interface IPhone{/// <summary>/// 打电话方法/// </summary>void Call();/// <summary>/// 发短信方法/// </summary>void Text();}/// <summary>/// Services层/// </summary>public class ApplePhone : IPhone{private IPhone? iPhone;public ApplePhone(IPhone? iPhone){this.iPhone = iPhone;}/// <summary>/// 打电话方法/// </summary>public void Call(){Console.WriteLine("{0}打电话", this.GetType().Name);}/// <summary>/// 发短信方法/// </summary>public void Text(){Console.WriteLine("{0}发短信", this.GetType().Name);}}
}

三：依赖注入内置Ioc容器

MicroPhone没有依赖。

HeadPhone依赖MicroPhone。

ApplePhone依赖HeadPhone。

IPhone关键代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Study_ASP.NET_Core_MVC.Interfaces
{public interface IPhone{IMicroPhone MicroPhone { get; set; }IHeadPhone HeadPhone { get; set; }/// <summary>/// 打电话方法/// </summary>void Call();/// <summary>/// 发短信方法/// </summary>void Text();/// <summary>/// 显示当前时间信息/// </summary>/// <param name="msgInfo">时间信息</param>/// <returns></returns>string ShowTime(string timeInfo);}public interface IMicroPhone { }public interface IHeadPhone { }
}

ApplePhone关键代码：

using Study_ASP.NET_Core_MVC.Interfaces;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Study_ASP.Net_Core_MVC.Services
{public class ApplePhone : IPhone{public IMicroPhone MicroPhone { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }public IHeadPhone HeadPhone { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }public ApplePhone(){Console.WriteLine("{0}无参构造函数", this.GetType().Name);}public ApplePhone(IHeadPhone headPhone){Console.WriteLine("{0}有参构造函数：{1}", this.GetType().Name,headPhone);}/// <summary>/// 打电话方法/// </summary>public void Call(){Console.WriteLine("{0}打电话", this.GetType().Name);}/// <summary>/// 发短信方法/// </summary>public void Text(){Console.WriteLine("{0}发短信", this.GetType().Name);}/// <summary>/// 显示当前时间信息/// </summary>/// <param name="msgInfo">时间信息</param>/// <returns></returns>public string ShowTime(string timeInfo){Console.WriteLine("显示时间：{0}", timeInfo);return $"当前时间：{timeInfo}";}}
}

HeadPhone关键代码：

using Study_ASP.NET_Core_MVC.Interfaces;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Study_ASP.Net_Core_MVC.Services
{public class HeadPhone : IHeadPhone{private IMicroPhone microPhone;public HeadPhone(IMicroPhone iMicroPhone){Console.WriteLine($"{this.GetType().Name}被构造。。");this.microPhone = iMicroPhone;}}
}

MicroPhone关键代码：

using Study_ASP.NET_Core_MVC.Interfaces;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Study_ASP.Net_Core_MVC.Services
{public class MicroPhone : IMicroPhone{public MicroPhone(){Console.WriteLine($"{this.GetType().Name}被构造。。。");}}
}

Program关键代码：

//表示整个应用程序，调用CreateBuilder方法创建一个WebApplicationBuilder对象。
//初始化当前应用程序的管道容器
using Microsoft.Extensions.DependencyInjection;
using Study_ASP.Net_Core_MVC.Services;
using Study_ASP.NET_Core_MVC.Interfaces;var builder = WebApplication.CreateBuilder(args);
//向管道容器添加注册中间件
//添加注册控制器视图中间件
builder.Services.AddControllersWithViews();
//添加注册Session中间件
builder.Services.AddSession();
//配置管道容器中间件，构造WebApplication实例
//注册Ioc容器服务
builder.Services.AddTransient<IMicroPhone, MicroPhone>();
builder.Services.AddTransient<IHeadPhone, HeadPhone>();
builder.Services.AddTransient<IPhone, ApplePhone>();
var app = builder.Build();
//判断是否是开发模式
if (!app.Environment.IsDevelopment())
{//向管道中添加中间件，该中间件将捕获异常、记录异常、重置请求路径并重新执行请求。app.UseExceptionHandler("/Shared/Error");//向管道中添加用于使用HSTS的中间件，该中间件添加了Strict Transport Security标头。默认值为30天app.UseHsts();
}
//向管道添加Session中间件
app.UseSession();
//向管道添加用于将HTTP请求重定向到HTTPS的中间件。
app.UseHttpsRedirection();
//向管道添加为当前请求路径启用静态文件服务
app.UseStaticFiles();
//向管道添加路由配置中间件
app.UseRouting();
//向管道添加鉴权中间件
app.UseAuthentication();
//向管道添加授权中间件
app.UseAuthorization();
//向管道添加默认路由中间件
app.MapControllerRoute(name: "default",pattern: "{controller=Home}/{action=Index}/{id?}");
//向管道添加启动应用程序中间件
app.Run();

控制器关键代码：

using Microsoft.AspNetCore.Mvc;
using Study_ASP.Net_Core_MVC.Services;
using Study_ASP.NET_Core_MVC.Interfaces;
using Study_ASP.NET_Core_MVC.Models;
using System.Diagnostics;namespace Study_ASP.NET_Core_MVC.Controllers
{public class HomeController : Controller{/// <summary>/// 定义构造函数/// </summary>private readonly ILogger<HomeController> _logger;private readonly IPhone iPhone;private readonly IMicroPhone microPhone;private readonly IHeadPhone headPhone;/// <summary>/// 初始化构造函数/// </summary>/// <param name="logger"></param>public HomeController(ILogger<HomeController> logger, IPhone iPhone,IMicroPhone microPhone,IHeadPhone headPhone){_logger = logger;this.iPhone = iPhone;this.microPhone = microPhone;this.headPhone = headPhone;}/// <summary>/// Get请求/// Home控制器/// Index方法/// </summary>/// <returns></returns>[HttpGet]public IActionResult Index(){//调用打电话方法iPhone.Call();//调用发短信方法iPhone.Text();//电泳显示实践方法ViewBag.ShowTime =  iPhone.ShowTime(DateTime.Now.ToString("yyyy-MM-dd HH-mm-ss"));return View();}}
}

视图代码：

@{ViewData["Title"] = "Home Page";
}<div class="text-center"><h1 class="display-4">Welcome</h1><h1 class="display-4">@ViewBag.ShowTime</h1><p>Learn about <a href="https://docs.microsoft.com/aspnet/core">building Web apps with ASP.NET Core</a>.</p>
</div>

结果：

四：生命周期

瞬时生命周期：Transient：AddTransient：在整个应用程序中，每次请求都会创建一个全新的实例。生命周期最短。

单例生命周期：Singleton：AddSingleton：在整个应用程序中，创建一个实例，后续请求都会使用该实例。生命周期最长。

作用域生命周期：Scoped：AddScoped：在整个应用程序中，同一个域内，创建一个实例，后续请求都会使用该实例。

五：多种注册方式

public static void Main(string[] args){//注册抽象和具体普通类{ServiceCollection serviceCollection = new ServiceCollection(); serviceCollection.AddTransient<IPhone, ApplePhone>();ServiceProvider serviceProvider = serviceCollection.BuildServiceProvider();IPhone iPhone = serviceProvider.GetService<IPhone>();//6：内置容器调用方法iPhone.Call();iPhone.Text();}//注册抽象和具体普通类{ServiceCollection serviceCollection = new ServiceCollection();serviceCollection.AddTransient(typeof(IPhone), typeof(ApplePhone));ServiceProvider serviceProvider = serviceCollection.BuildServiceProvider();IPhone iPhone = serviceProvider.GetService<IPhone>();//6：内置容器调用方法iPhone.Call();iPhone.Text();}//注册具体抽象类{ServiceCollection serviceCollection = new ServiceCollection();serviceCollection.AddTransient(typeof(ApplePhone));ServiceProvider serviceProvider = serviceCollection.BuildServiceProvider();ApplePhone applePhone = serviceProvider.GetService<ApplePhone>();//6：内置容器调用方法applePhone.Call();applePhone.Text();}//注册具体抽象类{ServiceCollection serviceCollection = new ServiceCollection();serviceCollection.AddTransient<ApplePhone>();ServiceProvider serviceProvider = serviceCollection.BuildServiceProvider();ApplePhone applePhone = serviceProvider.GetService<ApplePhone>();//6：内置容器调用方法applePhone.Call();applePhone.Text();}//注册抽象类和一段业务逻辑{ServiceCollection serviceCollection = new ServiceCollection();serviceCollection.AddTransient(typeof(IPhone), provider =>{//业务逻辑return provider;});serviceCollection.AddTransient(typeof(IPhone), typeof(ApplePhone));ServiceProvider serviceProvider = serviceCollection.BuildServiceProvider();IPhone iPhone = serviceProvider.GetService<IPhone>();//6：内置容器调用方法iPhone.Call();iPhone.Text();}Console.ReadLine();}