abp中将生命周期事件抽象为4个接口：

//预初始化
public interface IOnPreApplicationInitialization
{void OnPreApplicationInitialization([NotNull] ApplicationInitializationContext context);
}//初始化
public interface IOnApplicationInitialization
{void OnApplicationInitialization([NotNull] ApplicationInitializationContext context);
}//初始化完成
public interface IOnPostApplicationInitialization
{void OnPostApplicationInitialization([NotNull] ApplicationInitializationContext context);
}//关闭
public interface IOnApplicationShutdown
{void OnApplicationShutdown([NotNull] ApplicationShutdownContext context);
}

abp定义了一个模块生命周期接口，该接口只有两个方法，用于初始化和关闭。

public interface IModuleLifecycleContributor : ITransientDependency
{void Initialize([NotNull] ApplicationInitializationContext context, [NotNull] IAbpModule module);void Shutdown([NotNull] ApplicationShutdownContext context, [NotNull] IAbpModule module);
}

这个接口的参数是IAbpModule接口的类型，也就是派生自AbpModule的模块类型。该接口有一个默认实现，是一个抽象类，主要是用于复用。

public abstract class ModuleLifecycleContributorBase : IModuleLifecycleContributor
{public virtual void Initialize(ApplicationInitializationContext context, IAbpModule module){}public virtual void Shutdown(ApplicationShutdownContext context, IAbpModule module){}
}

abp根据四个生命周期分别有四个类型，这四个类型是基于模块生命周期基类创建的。

public class OnApplicationInitializationModuleLifecycleContributor : ModuleLifecycleContributorBase
{public override void Initialize(ApplicationInitializationContext context, IAbpModule module){(module as IOnApplicationInitialization)?.OnApplicationInitialization(context);}
}public class OnApplicationShutdownModuleLifecycleContributor : ModuleLifecycleContributorBase
{public override void Shutdown(ApplicationShutdownContext context, IAbpModule module){(module as IOnApplicationShutdown)?.OnApplicationShutdown(context);}
}public class OnPreApplicationInitializationModuleLifecycleContributor : ModuleLifecycleContributorBase
{public override void Initialize(ApplicationInitializationContext context, IAbpModule module){(module as IOnPreApplicationInitialization)?.OnPreApplicationInitialization(context);}
}public class OnPostApplicationInitializationModuleLifecycleContributor : ModuleLifecycleContributorBase
{public override void Initialize(ApplicationInitializationContext context, IAbpModule module){(module as IOnPostApplicationInitialization)?.OnPostApplicationInitialization(context);}
}

只有"关闭应用"这个生命周期实现Shutdown方法，其余的都是实现Initialize方法。最后是传入的参数abp模块去调用对应的生命周期。
剖析图如下：