Microsoft.Extensions.DependencyInjection会自动释放通过DI（依赖注入）创建的对象

Microsoft.Extensions.DependencyInjection中（下面简称DI），在调用ServiceProvider和IServiceScope对象的Dispose()方法时，也会自动调用ServiceProvider和IServiceScope对象通过DI创建的对象的Dispose()方法（前提是，通过DI创建的对象实现了IDisposable接口）。

我们新建一个.NET Core控制台项目，然后假设我们有接口IPeople和类People，类People实现了接口IPeople和IDisposable，接口IPeople和类People之间的依赖注入关系是Transient。

如果我们用ServiceProvider对象通过DI创建一个People对象，那么当调用ServiceProvider对象的Dispose()方法时，People对象的Dispose()方法也会被自动调用：

using Microsoft.Extensions.DependencyInjection;
using System;

namespace NetCoreDITransientInScope
{
    interface IPeople
    {
        void DoSomething();
    }

    class People : IPeople, IDisposable
    {
        public void Dispose()
        {
            Console.WriteLine("Disposing People");
        }

        public void DoSomething()
        {
            Console.WriteLine("DoSomething is running");
        }
    }

    class Program
    {

        static void Main(string[] args)
        {
            IServiceCollection services = new ServiceCollection();
            services.AddTransient<IPeople, People>();//注册接口IPeople和类People的关系为Transient

            ServiceProvider rootServiceProvider = null;

            try
            {
                rootServiceProvider = services.BuildServiceProvider();
                IPeople people = rootServiceProvider.GetService<IPeople>();
                people.DoSomething();
            }
            finally
            {
                if (rootServiceProvider != null)
                {
                    rootServiceProvider.Dispose();//调用ServiceProvider.Dispose()方法，也会调用ServiceProvider通过DI创建的people对象的Dispose()方法
                }
            }

            Console.WriteLine("Press any key to end...");
            Console.ReadKey();
        }
    }
}

 

如果我们用IServiceScope对象的ServiceProvider通过DI创建一个People对象，那么当调用IServiceScope对象的Dispose()方法时，People对象的Dispose()方法也会被自动调用：

using Microsoft.Extensions.DependencyInjection;
using System;

namespace NetCoreDITransientInScope
{
    interface IPeople
    {
        void DoSomething();
    }

    class People : IPeople, IDisposable
    {
        public void Dispose()
        {
            Console.WriteLine("Disposing People");
        }

        public void DoSomething()
        {
            Console.WriteLine("DoSomething is running");
        }
    }

    class Program
    {

        static void Main(string[] args)
        {
            IServiceCollection services = new ServiceCollection();
            services.AddTransient<IPeople, People>();//注册接口IPeople和类People的关系为Transient

            ServiceProvider rootServiceProvider = null;
            IServiceScope serviceScope = null;

            try
            {
                rootServiceProvider = services.BuildServiceProvider();

                try
                {
                    serviceScope = rootServiceProvider.CreateScope();
                    IPeople people = serviceScope.ServiceProvider.GetService<IPeople>();
                    people.DoSomething();
                }
                finally
                {
                    if (serviceScope != null)
                    {
                        serviceScope.Dispose();//调用IServiceScope.Dispose()方法，也会调用在IServiceScope中通过DI创建的people对象的Dispose()方法
                    }
                }

            }
            finally
            {
                if (rootServiceProvider != null)
                {
                    rootServiceProvider.Dispose();
                }
            }

            Console.WriteLine("Press any key to end...");
            Console.ReadKey();
        }
    }
}

 

关于Microsoft.Extensions.DependencyInjection会自动释放DI创建的对象，可以查看下面这篇微软的官方文档：

Disposal of services

注意这里有提到，如果一个对象是由开发人员自己new出来的，而不是由DI创建的，那么该对象是不会被DI自动释放的，需要开发人员自己去释放：

Services not created by the service container

 

关于Microsoft.Extensions.DependencyInjection的详细介绍，可以查看下面微软的官方文档：

.NET dependency injection