private static Func <Type, ServiceCallSite> GetCallSiteFactory(params ServiceDescriptor[] descriptors)
{
var collection = new ServiceCollection();
foreach (var descriptor in descriptors)
{
collection.Add(descriptor);
}
var callSiteFactory = new CallSiteFactory(collection.ToArray());
return(type => callSiteFactory.GetCallSite(type, new CallSiteChain()));
}
private Func <ServiceProviderEngineScope, object> CreateServiceAccessor(Type serviceType)
{
ServiceCallSite callSite = CallSiteFactory.GetCallSite(serviceType, new CallSiteChain());
if (callSite != null)
{
DependencyInjectionEventSource.Log.CallSiteBuilt(serviceType, callSite);
_callback?.OnCreate(callSite);
return(RealizeService(callSite));
}
return(_ => null);
}
private Func <ServiceProviderEngineScope, object> CreateServiceAccessor(Type serviceType) // 这个方法的作用是根据服务类型，创建对应的产生服务实例的委托方法。
// 这个方法会在 CallSiteFactory 中查找输入服务类型对应的创建服务实例有关的信息。并将得到的 callSite 信息传入由子类实现的 RealizeService 方法。最后将 RealizeService 方法返回。
// 如果 CallSiteFactory 中没有对应的信息， 就会将 CallSiteFactory 在内部新添加这个信息（运行时动态添加）
{
var callSite = CallSiteFactory.GetCallSite(serviceType, new CallSiteChain());
if (callSite != null)
{
_callback?.OnCreate(callSite);
return(RealizeService(callSite));
}
return(_ => null);
}
public void ValidateService(ServiceDescriptor descriptor)
{
if (descriptor.ServiceType.IsGenericType && !descriptor.ServiceType.IsConstructedGenericType)
{
return;
}
try
{
ServiceCallSite callSite = CallSiteFactory.GetCallSite(descriptor, new CallSiteChain());
if (callSite != null)
{
_callback?.OnCreate(callSite);
}
}
catch (Exception e)
{
throw new InvalidOperationException($"Error while validating the service descriptor '{descriptor}': {e.Message}", e);
}
}
