(82) C# .net core 依赖注入

  

控制反转的两种方式：1 服务定位器，2 依赖注入

服务定位器

一、服务定位器

服务：就是找框架要的一个对象

引入  Microsoft.Extensions.DependencyInjection

对象生命周期

1. AddTransient 瞬时生命周期

 每次serviceProvider.GetService<Test>(); 都会创建一个对象

ServiceCollection services = new ServiceCollection();
//把对象放入
services.AddTransient<Test>();

ServiceProvider serviceProvider = services.BuildServiceProvider();
Test testService = serviceProvider.GetService<Test>();
testService.Name = "liu";
testService.Hi();

public interface ITestService
{
    public string Name { get; set; }
    public void Hi();
}

public class Test : ITestService
{
    public string Name { get ; set; }

    public void Hi()
    {
        Console.WriteLine($"打印{Name}");
    }
}

2.唯一对象AddSingleton

services.AddSingleton<Test>();

ServiceCollection services = new ServiceCollection();
//把对象放入
services.AddTransient<Test>();

ServiceProvider serviceProvider = services.BuildServiceProvider();
Test testService = serviceProvider.GetService<Test>();
testService.Name = "liu";
testService.Hi();

Test testService1 = serviceProvider.GetService<Test>();
testService1.Name = "tom";
testService.Hi();
testService1.Hi();

3.范围内

ServiceCollection services = new ServiceCollection();
//把对象放入
services.AddScoped<Test>();
ServiceProvider serviceProvider = services.BuildServiceProvider();

//IServiceScope域 范围内相同
using (IServiceScope servicesScope = serviceProvider.CreateScope())
{
    Test testService = servicesScope.ServiceProvider.GetService<Test>();
    Test testService2 = servicesScope.ServiceProvider.GetService<Test>();

    

}

using (IServiceScope servicesScope2 = serviceProvider.CreateScope())
{
    Test testService = servicesScope2.ServiceProvider.GetService<Test>();
    Test testService2 = servicesScope2.ServiceProvider.GetService<Test>();

}

使用接口实现

ServiceCollection services = new ServiceCollection();
//传入接口和实现类
services.AddTransient<ITestService,Test>();
ServiceProvider serviceProvider = services.BuildServiceProvider();
//
ITestService testService = serviceProvider.GetService<ITestService>();

testService.Name = "liu";
testService.Hi();
//查看testService实际类型为Test
Console.WriteLine(testService.GetType());

二、依赖注入

ServiceCollection services = new ServiceCollection();
services.AddTransient<Test>();
services.AddTransient<A>();
var s=services.BuildServiceProvider().GetService<Test>();
s.ok();

public interface ITest
{
    void ok();
}

public class Test : ITest
{
    A a;
    public Test(A a)
    {
        this.a = a;
    }
    public void ok()
    {
        Console.WriteLine("打印ok方法");
        a.AAA();
    }
}

public interface IA
{
    void AAA();
}

public class A
{
    public void AAA()
    {
        Console.WriteLine("打印AAA方法");
    }
}