.netcore依赖注入

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依赖注入是有“传染性”的，如果一个类的对象是通过DI创建的，那么这个类的构造函数中声明的所有服务类型的参数都会被DI赋值；
但是如果一个对象是程序员手动创建的，那么这个对象就和DI没有关系，它的构造函数中声明的服务类型参数就不会被自动赋值
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<div .net默认构造函数注入>
<div 除了构造函数注入， 还可以通过写函数时，对函数参数加[FromService] 标记依赖注入>
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依赖注入的步骤:

1 创立IOC容器
ServiceCollection services = new ServiceCollection();

2 向IOC注册
services.AddScoped<ITestService, TestServicelmp1>

3 建立服务定位器 Locator
ServiceProvider sp = services.BuildServiceProvider()

4 从Locator中拿出方法GetService
ITestService ts1 = sp.GetService<ITestService>();

using System;
using System.Reflection;
using Microsoft.Extensions.DependencyInjection;

namespace DependencyInjection
{
    class Program
    {
        static void Main(string[] args)
        {
            //var driver = new Driver(new HeavyTank());
            //driver.Drive();
            接口隔离的好处就是, 有选择性的继承对象的一部分属性
            在这里, driver并没有Fire方法, 只有Diver()
            //var dv1 = driver as ITank;
            //dv1.Fire();
            此处的dv1 有了Fire() 因为传进来的HeavyTank 继承了 ITank, 而ITank继承了IWeapon
            //var dv2 = (ITank)driver;
            //dv2.Fire();
            此处的dv2 也有了Fire()
            //Console.ReadKey();

            //反射的原理: 通过描述找到方法
            //ITank tank = new HeavyTank();
            //var t = tank.GetType();
            //object o = Activator.CreateInstance(t);
            //MethodInfo fireMi = t.GetMethod("Fire");
            //MethodInfo runMi = t.GetMethod("Run");
            //fireMi.Invoke(o, null);
            //runMi.Invoke(o, null);
            //Console.ReadKey();


            var serviceContainer = new ServiceCollection();
            serviceContainer.AddScoped(typeof(ITank), typeof(HeavyTank)); //Type serviceType, Type implementationType
            serviceContainer.AddScoped(typeof(IVehicle), typeof(Car)); //方法类型
            serviceContainer.AddScoped<Driver>(); //构造器<Driver> 将方法类型 注入到构造器
            var serviceProvider = serviceContainer.BuildServiceProvider();
            //--------------分割线----------------以上为注册过程
            ITank tank = serviceProvider.GetService<ITank>();
            tank.Fire();
            tank.Run();
            //Console.ReadKey();
            var driver = serviceProvider.GetService<Driver>();
            driver.Drive();
            Console.ReadKey();  

            
        }
    }

    class Driver
    {
        private IVehicle _vehicle; //此处使用了接口隔离, 
        public Driver(IVehicle vehicle)
        {
            _vehicle = vehicle;
        }

        public void Drive()
        {
            _vehicle.Run();
        }
    }

    interface IVehicle
    {
        public void Run();
    }

    interface IWeapon
    {
        public void Fire();
    }
    interface ITank:IVehicle,IWeapon
    {

    }

    //interface ITank
    //{
    //    void Fire();
    //    void Run();
    //}

    class Car : IVehicle
    {
        public void Run()
        {
            Console.WriteLine("Car is running");
        }
    }

    class Truck : IVehicle
    {
        public void Run()
        {
            Console.WriteLine("Truck is running");
        }
    }




    class LightTank : ITank
    {
        public void Fire()
        {
            Console.WriteLine("Boom!");
        }

        public void Run()
        {
            Console.WriteLine("Ka ka ka!");
        }
    }

    class MediumTank : ITank
    {
        public void Fire()
        {
            Console.WriteLine("Boom!!");
        }

        public void Run()
        {
            Console.WriteLine("Ka ka ka!!");
        }
    }

    class HeavyTank : ITank
    {
        public void Fire()
        {
            Console.WriteLine("Boom!!!");
        }

        public void Run()
        {
            Console.WriteLine("Ka ka ka!!!");
        }
    }


}

using Microsoft.Extensions.DependencyInjection;
using System;

namespace DependencyInjectionDemon
{
    class Program
    {
        static void Main(string[] arges)
        {
            ServiceCollection services = new ServiceCollection();
            services.AddScoped<ITestService, TestServicelmp1>();//服务的类型, 实现的类型
            //services.AddScoped(typeof(ITestService), typeof(TestServicelmp1));//与上面一样

            using (ServiceProvider sp = services.BuildServiceProvider())
            {
                //TestServicelmp1 ts1 = sp.GetService<ITestService>();
                ITestService ts1 = sp.GetService<ITestService>();
                ts1.Name = "宋江";
                ts1.SayHi();
                Console.WriteLine(ts1.GetType());
            }
        }

        static void Main1(string[] args)
        {
            ServiceCollection services = new ServiceCollection(); //构造容器对象
            services.AddTransient<TestServicelmp1>(); //添加瞬态服务
            using (ServiceProvider sp = services.BuildServiceProvider()) //创建provider 相当于serviceLocator 服务定位器
            {
                //服务定位器
                TestServicelmp1 t = sp.GetService<TestServicelmp1>(); //向Provider要对象
                t.Name = "西门庆";
                

                TestServicelmp1 t1 = sp.GetService<TestServicelmp1>();
                t1.Name = "武大郎";

                t.SayHi();
                t1.SayHi();
                Console.WriteLine("--------------------");
                Console.WriteLine(object.ReferenceEquals(t,t1));

                //I am 西门庆
                //I am 武大郎
                //--------------------
                //False
            }

            services.AddSingleton<TestServicelmp1>(); //添加单例
            using (ServiceProvider sp = services.BuildServiceProvider()) //创建provider 相当于serviceLocator 服务定位器
            {
                //服务定位器
                TestServicelmp1 t = sp.GetService<TestServicelmp1>(); //向Provider要对象
                t.Name = "西门庆";
                
                TestServicelmp1 t1 = sp.GetService<TestServicelmp1>();
                t1.Name = "武大郎";

                t.SayHi();
                t1.SayHi();
                Console.WriteLine("--------------------");
                Console.WriteLine(object.ReferenceEquals(t, t1));
                //I am 武大郎
                //I am 武大郎
                //--------------------
                //True
            }

            services.AddScoped<TestServicelmp1>(); //添加范围对象
            using (ServiceProvider sp = services.BuildServiceProvider()) //创建provider 相当于serviceLocator 服务定位器
            {
                using (IServiceScope scope1 = sp.CreateScope())
                {
                    //在scope中获取Scope相关的对象 scope1.ServiceProvider而不是sp
                    //scope1.ServiceProvider.GetService<TestServicelmp1>();

                    //服务定位器
                    TestServicelmp1 t = scope1.ServiceProvider.GetService<TestServicelmp1>(); //向Provider要对象
                    t.Name = "西门庆";

                    TestServicelmp1 t1 = scope1.ServiceProvider.GetService<TestServicelmp1>();
                    t1.Name = "武大郎";

                    t.SayHi();
                    t1.SayHi();
                    Console.WriteLine("--------------------");
                    Console.WriteLine(object.ReferenceEquals(t, t1));
                    //I am 武大郎
                    //I am 武大郎
                    //--------------------
                    //True
                }
            }
        }
    }
}

// See https://aka.ms/new-console-template for more information
using ConfigTestDemon;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;

//ConfigurationBuilder cfgBuilder = new ConfigurationBuilder();

optional: true 可以检测报错  reloadOnChange: true 自动加载. json设置成更新时复制
//cfgBuilder.AddJsonFile("config.json", optional: true, reloadOnChange: true);
//IConfigurationRoot configRoot = cfgBuilder.Build();

//Console.WriteLine("--------------原始方法----------------------------------");
//string name = configRoot["name"];
//Console.WriteLine($"name={name}");

//string add = configRoot.GetSection("proxy:address").Value;

//Console.WriteLine($"addr={add}");

//Console.WriteLine("--------------使用微软的Configuration.Binder----------------------------------");
使用微软的Configuration.Binder

//Proxy proxy = configRoot.GetSection("proxy").Get<Proxy>();
//Console.WriteLine($"IP地址是:{ proxy.Address},端口号是{proxy.Port}");


//Console.WriteLine("--------------直接读取根节点----------------------------");

//Config config = configRoot.Get<Config>();

//Console.WriteLine($"姓名是{config.Name}, 年龄是{config.Age}, IP地址是:{ config.Proxy.Address},端口号是{config.Proxy.Port}");


///*
// 结果:
//--------------原始方法----------------------------------
//name=zg
//addr=aa
//--------------使用微软的Configuration.Binder----------------------------------
//IP地址是:aa,端口号是8080
//--------------直接读取根节点----------------------------
//姓名是zg, 年龄是18, IP地址是:aa,端口号是8080

// */

//Console.WriteLine("--------------使用DI依赖注入----------------------------");

ConfigurationBuilder cfgBuilder = new ConfigurationBuilder();

//使用CommandLine

//optional: true 可以检测报错  reloadOnChange: true 自动加载. json设置成更新时复制
cfgBuilder.AddJsonFile("config.json", optional: true, reloadOnChange: true);
IConfigurationRoot configRoot = cfgBuilder.Build();

ServiceCollection services = new ServiceCollection(); //构造容器对象
services.AddScoped<TestController>(); //注册
services.AddScoped<OnlyProxy>();

//向IOC中注册AddOptions
//将Config对象绑在根节点configRoot
services.AddOptions()
    .Configure<Config>(e => configRoot.Bind(e))
    .Configure<Proxy>(e => configRoot.GetSection("proxy").Bind(e));

using (ServiceProvider sp = services.BuildServiceProvider()) //创建provider对象
{
    while (true)
    {
        await Task.Delay(1000);
        using (var scope = sp.CreateScope())
        {
            //新建CreateScope 可以自动刷新文本json的改变
            Console.WriteLine("-----------读取完整的TestController---Test方法实现----------------------------");
            var c = sp.GetRequiredService<TestController>();
            c.Test();
            Console.WriteLine("-----------只读取Proxy的地址和端口号---Test方法实现----------------------------");
            var c2 = sp.GetRequiredService<OnlyProxy>();
            c2.Test();
        }
    }




    /*
     * 结果:
     --------------使用DI依赖注入----------------------------
    -----------读取完整的TestController---Test方法实现----------------------------
    18
    ---------------
    aa
    -----------只读取Proxy的地址和端口号---Test方法实现----------------------------
    用OnlyProxy实现IP为aa,端口号为:8080
     */
}





public class Proxy
{
    public string? Address  { get; set; }
    public string? Port { get; set; }
}

public class Config
{
    public string? Name { get; set; }
    public string? Age { get; set; }

    public Proxy? Proxy { get; set; }
}

原文链接：https://blog.csdn.net/helldoger/article/details/123824494

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