ServiceCollection services = new ServiceCollection();//定义一个承放服务的集合
services.AddScoped<iGetRole, GetRole>();using (ServiceProvider serviceProvider = services.BuildServiceProvider())
{var list = serviceProvider.GetServices(typeof(iGetRole));//获取到所有注册iGetRole类的实现对象foreach (var item in list){}}

    var list = serviceProvider.GetServices(typeof(iGetRole));//如果获取不到 则返回nullvar t = serviceProvider.GetRequiredService<iGetRole>();//如果获取不到 则抛出异常

DI注入方式

默认：构造函数注入；属性注入；

---------------------------------------------------------------------------------------------------------------------------------

自动注入示例：

public class MailKitService : IMailKitService
{private readonly ILogService _logService;private readonly IConfigService _configService;public MailKitService(ILogService _logService, IConfigService _configService){this._logService = _logService;this._configService = _configService;}public void SendMail(string address, string copyAddress, string title, string content){_logService.LogInfo($"发送地址：{address}");throw new NotImplementedException();}
}ServiceCollection services = new ServiceCollection();services.AddScoped<IConfigService, ConfigService>();
services.AddScoped<ILogService, LogService>();
services.AddScoped<IMailKitService, MailKitService>();using (var provider = services.BuildServiceProvider())
{var mailService = provider.GetRequiredService<IMailKitService>();//实现IMailKitService服务的 MailKitService构造函数会自动被注入ConfigService、LogService值mailService.SendMail("11","","","");}

---------------------------------------------------------------------------------------------------------------------------------

自定义扩展方法，与扩展对象同命名空间，使用this,使用地方可以直接点出来。（必须是静态类）