基类，派生类和Iclass？
[英]Base class, derived class, and Iclass?
问题描述
我试图弄清楚一位高级开发人员编写的代码是如何工作的，我感到非常困惑。 我希望有人可以帮助我理解该项目中存在的所有不同类和接口。
我的类库dll中存在一个外部类，与我正在编辑的Web应用程序分开。 我们称它为outsideClass。 我无法弄清楚为什么这个类有那么多的构造函数，以及如何发出请求，因为只有一个构造函数具有默认的WebRequestHandler，其余的则没有。 在Web应用程序中，此类的实例被初始化为WebRequestHandler为空！ 这让我发疯了...这是outsideClass：
public class outsideClass : webServiceInterface
{
private HttpClient _client = null;
private const int _TIMEOUT = 50;
private const string _assemblyName = "my.assembly.name";
private const string _resourcesName = "my.assembly.name.Properties.Resources";
private const string _certName = "client_cert_name";
private static WebRequestHandler CreateDefaultMessageHandler()
{
// ProgressMessageHandler prog = new ProgressMessageHandler();
//HttpClientHandler handler = new HttpClientHandler();
WebRequestHandler handler = new WebRequestHandler();
// The existing HttpClientHandler.SupportsProxy property indicates whether both the UseProxy property and the Proxy property are supported.
// This created an issue because some platforms(for example, Windows Phone) don’t allow you to configure a proxy explicitly.
// However, Windows Phone lets you control whether the machine wide proxy should be used.
// To model this behavior, we added the HttpClientHandler.SupportsUseProxy() extension method.
// For some platforms that don’t support both, such as Windows Phone, the SupportsProxy property will continue to return false, but the SupportsUseProxy() method will return true.
if (handler.SupportsProxy) // false on WinPhone
{
handler.Proxy = CrossWebProxy.SystemWebProxy;
handler.UseProxy = true;
}
// HttpClientHandler.SupportsAllowAutoRedirect(): The HttpClientHandler.SupportsRedirectConfiguration property had a similar issue:
// It controls whether both the AllowAutoRedirect and the MaxAutomaticRedirections properties are supported.
// Windows Phone doesn’t support specifying the maximum number of automatic redirections, but it does support redirection.
// For that reason, we added the HttpClientHandler.SupportsAllowAutoRedirect() extension method.
/*
if (handler.SupportsRedirectConfiguration) // false on WinPhone
{
handler.MaxAutomaticRedirections = 5;
} */
if (handler.SupportsRedirectConfiguration)
{
handler.AllowAutoRedirect = true;
}
X509Certificate2 certificate = getClientCertificate();
handler.ClientCertificates.Add(certificate);
return handler;
}
private static X509Certificate2 getClientCertificate()
{
System.Reflection.Assembly myAssembly;
myAssembly = System.Reflection.Assembly.Load(_assemblyName);
ResourceManager myManager = new ResourceManager(_resourcesName, myAssembly);
byte[] cert_file_bytes;
cert_file_bytes = (byte[])myManager.GetObject(_certName);
//string[] names = myAssembly.GetManifestResourceNames();
//using (Stream cert_file_stream = myAssembly.GetManifestResourceStream(names[0]))
//using (var streamReader = new MemoryStream())
//{
// cert_file_stream.CopyTo(streamReader);
// cert_file_bytes = streamReader.ToArray();
//}
X509Certificate2 cert_file = new X509Certificate2(cert_file_bytes, "server");
return cert_file;
}
public outsideClass(params DelegatingHandler[] handlers) : this(null, handlers)
{
}
public outsideClass(WebRequestHandler innerHandler, params DelegatingHandler[] handlers) : this("", "", innerHandler, handlers)
{
}
public outsideClass(string aUser, string aPass, params DelegatingHandler[] handlers) : this(aUser, aPass, null, null, handlers)
{
}
public outsideClass(string aUser, string aPass, Uri aBaseAddress, params DelegatingHandler[] handlers) : this(aUser, aPass, null, null, handlers)
{
}
public outsideClass(string aUser, string aPass, WebRequestHandler innerHandler, params DelegatingHandler[] handlers) : this(aUser, aPass, null, innerHandler, handlers)
{
}
public outsideClass(string aUser, string aPass, Uri aBaseAddress, WebRequestHandler innerHandler, params DelegatingHandler[] handlers)
{
if (innerHandler == null)
{
innerHandler = CreateDefaultMessageHandler();
}
if (handlers != null)
{
DelegatingHandler excHandler = handlers.FirstOrDefault(t => t is WebServiceExceptionsHandler);
if (excHandler == null)
{
// Add the custom handler to the list
// So this Client will raise only exception of type WebServiceException / WebServiceOfflineException / WebServiceTimedOutException / WebServiceStatusException
excHandler = new WebServiceExceptionsHandler();
IList<DelegatingHandler> list = handlers.ToList();
list.Insert(0, excHandler);
handlers = list.ToArray();
}
}
_client = HttpClientFactory.Create(innerHandler, handlers);
Timeout = TimeSpan.FromSeconds(_TIMEOUT);
SetCredentials(aUser, aPass);
BaseAddress = aBaseAddress;
}
protected long MaxResponseContentBufferSize
{
get { return _client.MaxResponseContentBufferSize; }
set { _client.MaxResponseContentBufferSize = value; }
}
protected HttpRequestHeaders DefaultRequestHeaders { get { return _client.DefaultRequestHeaders; } }
public Uri BaseAddress
{
get { return _client.BaseAddress; }
set { _client.BaseAddress = value; }
}
public TimeSpan Timeout
{
get { return _client.Timeout; }
set { _client.Timeout = value; }
}
public string Id { get; private set; }
public string Key { get; private set; }
/// <summary>
/// Set Basic Authentication Header
/// </summary>
public void SetCredentials(string aApplicationId, string aApplicationKey)
{
Id = aApplicationId;
Key = aApplicationKey;
_client.DefaultRequestHeaders.Authorization = null;
if (string.IsNullOrEmpty(Id) == true ||
string.IsNullOrEmpty(Key) == true)
{
return;
}
_client.DefaultRequestHeaders.Authorization =
new AuthenticationHeaderValue("Basic",
Convert.ToBase64String(System.Text.UTF8Encoding.UTF8.GetBytes(string.Format("{0}:{1}",
this.Id, this.Key))));
}
protected async Task<T> SendAndReadAsAsync<T>(HttpRequestMessage aRequest, MediaTypeFormatterCollection formatters, CancellationToken aCancellationToken = default(CancellationToken))
{
HttpResponseMessage response = await _client.SendAsync(aRequest, aCancellationToken).ConfigureAwait(false);
return await response.Content.ReadAsAsync<T>(formatters).ConfigureAwait(false);
}
protected async Task<T> SendAndReadAsAsync<T>(HttpRequestMessage aRequest, CancellationToken aCancellationToken = default(CancellationToken))
{
HttpResponseMessage response = await _client.SendAsync(aRequest, aCancellationToken).ConfigureAwait(false);
return await response.Content.ReadAsAsync<T>().ConfigureAwait(false);
}
protected async Task<string> SendAndReadAsStringAsync(HttpRequestMessage aRequest, CancellationToken aCancellationToken = default(CancellationToken))
{
HttpResponseMessage response = await _client.SendAsync(aRequest, aCancellationToken).ConfigureAwait(false);
return await response.Content.ReadAsStringAsync().ConfigureAwait(false);
}
protected async Task<Stream> SendAndReadAsStreamAsync(HttpRequestMessage aRequest, HttpCompletionOption aCompletionOption = HttpCompletionOption.ResponseHeadersRead, CancellationToken aCancellationToken = default(CancellationToken))
{
HttpResponseMessage response = await _client.SendAsync(aRequest, aCompletionOption, aCancellationToken).ConfigureAwait(false);
return await response.Content.ReadAsStreamAsync().ConfigureAwait(false);
}
protected async Task<byte[]> SendAndReadAsByteArrayAsync(HttpRequestMessage aRequest, CancellationToken aCancellationToken = default(CancellationToken))
{
HttpResponseMessage response = await _client.SendAsync(aRequest, aCancellationToken).ConfigureAwait(false);
return await response.Content.ReadAsByteArrayAsync().ConfigureAwait(false);
}
protected async Task<HttpResponseMessage> SendAsync(HttpRequestMessage aRequest, CancellationToken aCancellationToken = default(CancellationToken))
{
HttpResponseMessage response = await _client.SendAsync(aRequest, aCancellationToken).ConfigureAwait(false);
return response;
}
}
webServiceInterface（为什么需要这样做，目的是什么？）：
public interface webServiceInterface
{
Uri BaseAddress { get; set; }
TimeSpan Timeout { get; set; }
string Id { get; }
string Key { get; }
void SetCredentials(string aId, string aKey);
}
这是在Web应用程序中发现的令人困惑的代码，其中包含IConnClient和ConnClient类（为什么？），它们的定义如下：
public interface IConnClient : IClientWebService
{
Task UpdateSomethingAsync(Guid aCompanyId, Guid aUserId, Guid aAgronomistId, bool shareCN1, bool getRxMap, DateTime endDate, CancellationToken aCancelToken = default(CancellationToken));
Task<IList<SomethingDto>> GetSomethingListAsync(Guid aCompanyId, CancellationToken aCancelToken = default(CancellationToken));
Task DeleteSomethingAsync(Guid aCompanyId, Guid aAgronomistId, CancellationToken aCancelToken = default(CancellationToken));
Task<IList<StuffDto>> GetStuffListAsync(Guid aCompanyId, CancellationToken aCancelToken = default(CancellationToken));
Task<IList<StuffDto>> GetStuffListAsync(Guid aCompanyId, Guid aAgronomistId, CancellationToken aCancelToken = default(CancellationToken));
Task<IList<StuffDto>> GetStuffListForThingsAsync(Guid aCompanyId, Guid aThingsId, CancellationToken aCancelToken = default(CancellationToken));
Task<IList<ThingsDetailsDto>> GetThingsListAsync(Guid aCompanyId, CancellationToken aCancelToken = default(CancellationToken));
Task<string> SendStuffListToThingsListAsync(Guid aCompanyId, Guid aUserId, IList<StuffDto> aStuffList, IList<Guid> aThingsList, CancellationToken aCancelToken = default(CancellationToken));
// Task<bool> GetStuffStatusAsync(Guid aCompanyId, string aStuffId, CancellationToken aCancelToken = default(CancellationToken));
}
public class ConnClient : outsideClass, IConnClient
{
private const string _SHARE_CN1 = "Share-CN1";
private const string _GET_RXMAP = "Get-RxMap";
private DateTime Epoch2DateTime(long epoch)
{
return new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddMilliseconds(epoch);
}
private long DateTime2Epoch(DateTime datetime)
{
return (long)datetime.Subtract(new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds;
}
public ConnClient(Uri aBaseAddress, string apiKey, WebRequestHandler innerHandler = null, params DelegatingHandler[] handlers)
: base("", "", innerHandler, handlers) // DIP - IoC
{
DefaultRequestHeaders.Authorization = null; // TODO: Add authorization?
DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", apiKey);
BaseAddress = aBaseAddress;
}
public async Task UpdateSomethingAsync(Guid aCompanyId, Guid aUserId, Guid aAgronomistId, bool shareCN1, bool getRxMap, DateTime endDate, CancellationToken aCancelToken = default(CancellationToken))
{
if (aCompanyId == Guid.Empty)
throw new ArgumentException(nameof(UpdateSomethingAsync) + " Company GUID is Empty");
if (aUserId == Guid.Empty)
throw new ArgumentException(nameof(UpdateSomethingAsync) + " User GUID is Empty");
List<string> permissions = new List<string>();
if (shareCN1)
{
permissions.Add(_SHARE_CN1);
}
if (getRxMap)
{
permissions.Add(_GET_RXMAP);
}
UpdateSomethingRequestDto reqDto = new UpdateSomethingRequestDto();
reqDto.Somethings = new Somethings();
reqDto.Somethings.userId = aUserId;
reqDto.Somethings.thirdparty = aAgronomistId;
if (endDate.Year != 1)
reqDto.Somethings.endDate = DateTime2Epoch(endDate);
else
reqDto.Somethings.endDate = 0;
reqDto.Somethings.permissions = permissions;
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Put, "companies/" + aCompanyId + "/Somethings");
JsonMediaTypeFormatter fmt = new JsonMediaTypeFormatter();
request.Content = new ObjectContent(reqDto.GetType(), reqDto, fmt, "application/json");
var res = await SendAndReadAsStringAsync(request, aCancelToken);
}
public async Task<IList<SomethingDto>> GetSomethingListAsync(Guid aCompanyId, CancellationToken aCancelToken = default(CancellationToken))
{
if (aCompanyId == Guid.Empty)
throw new ArgumentException(nameof(GetSomethingListAsync) + " Company GUID is Empty");
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, "companies/" + aCompanyId + "/Somethings");
GetSomethingsResponseDto res = await SendAndReadAsAsync<GetSomethingsResponseDto>(request, aCancelToken);
return res?.Somethings;
}
public async Task DeleteSomethingAsync(Guid aCompanyId, Guid aAgronomistId, CancellationToken aCancelToken = default(CancellationToken))
{
if (aCompanyId == Guid.Empty)
throw new ArgumentException(nameof(DeleteSomethingAsync) + " Company GUID is Empty");
if (aAgronomistId == Guid.Empty)
throw new ArgumentException(nameof(DeleteSomethingAsync) + " Agronomist GUID is Empty");
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Delete, "companies/" + aCompanyId + "/Somethings?thirdPartyId=" + aAgronomistId);
var res = await SendAndReadAsStringAsync(request, aCancelToken);
}
public async Task<IList<StuffDto>> GetStuffListAsync(Guid aCompanyId, CancellationToken aCancelToken = default(CancellationToken))
{
if (aCompanyId == Guid.Empty)
throw new ArgumentException(nameof(GetStuffListAsync) + " Company GUID is Empty");
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, "companies/" + aCompanyId + "/Stuffs");
GetStuffsResponseDto res = await SendAndReadAsAsync<GetStuffsResponseDto>(request, aCancelToken);
return res?.Stuffs;
}
public async Task<IList<StuffDto>> GetStuffListAsync(Guid aCompanyId, Guid aAgronomistId, CancellationToken aCancelToken = default(CancellationToken))
{
if (aCompanyId == Guid.Empty)
throw new ArgumentException(nameof(GetStuffListAsync) + " Company GUID is Empty");
if (aAgronomistId == Guid.Empty)
return await GetStuffListAsync(aCompanyId);
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, "companies/" + aCompanyId + "/Stuffs?thirdPartyId=" + aAgronomistId);
GetStuffsResponseDto res = await SendAndReadAsAsync<GetStuffsResponseDto>(request, aCancelToken);
return res?.Stuffs;
}
public async Task<IList<ThingsDetailsDto>> GetThingsListAsync(Guid aCompanyId, CancellationToken aCancelToken = default(CancellationToken))
{
if (aCompanyId == Guid.Empty)
throw new ArgumentException(nameof(GetThingsListAsync) + " Company GUID is Empty");
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, "vehicles/?companyId=" + aCompanyId);
GetVehiclesResponseDto res = await SendAndReadAsAsync<GetVehiclesResponseDto>(request, aCancelToken);
return res?.vehicles;
}
private SendStuffsRequestDto CreateSendStuffDto(Guid aUserId, IList<StuffDto> aStuffList, IList<Guid> aVehicleList)
{
SendStuffsRequestDto res = new SendStuffsRequestDto();
res.StuffData = new List<StuffDataDto>();
res.userId = aUserId;
foreach (StuffDto prescr in aStuffList)
{
StuffDataDto data = new StuffDataDto();
data.StuffID = prescr.StuffId;
data.vehicles = aVehicleList;
res.StuffData.Add(data);
}
return res;
/*
SendStuffsRequestDto res = new SendStuffsRequestDto();
res.StuffData = new List<StuffDataDto>();
res.userId = aUserId;
foreach (StuffDto prescr in aStuffList)
{
IList<Guid> prescrVehicleList = prescr.vehicleDetails.Select(l => l.vehicleId).ToList();
IList<Guid> joinedList = aVehicleList.Where(c => prescrVehicleList.Contains(c)).ToList();
if (joinedList == null || joinedList.Count == 0)
continue;
StuffDataDto data = new StuffDataDto();
data.StuffID = prescr.StuffId;
data.vehicles = new List<Guid>();
data.vehicles = joinedList;
res.StuffData.Add(data);
}
return res;*/
}
public async Task<string> SendStuffListToThingsListAsync(Guid aCompanyId, Guid aUserId, IList<StuffDto> aStuffList, IList<Guid> aVehicleList, CancellationToken aCancelToken = default(CancellationToken))
{
if (aCompanyId == Guid.Empty)
throw new ArgumentException(nameof(SendStuffListToThingsListAsync) + " Company GUID is Empty");
if (aUserId == Guid.Empty)
throw new ArgumentException(nameof(SendStuffListToThingsListAsync) + " User GUID is Empty");
SendStuffsRequestDto reqDto = CreateSendStuffDto(aUserId, aStuffList, aVehicleList);
if (reqDto.StuffData.Count == 0)
return "";
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, "companies/" + aCompanyId + "/Stuffs/send");
JsonMediaTypeFormatter fmt = new JsonMediaTypeFormatter();
request.Content = new ObjectContent(reqDto.GetType(), reqDto, fmt, "application/json");
return await SendAndReadAsStringAsync(request, aCancelToken);
}
public async Task<IList<StuffDto>> GetStuffListForThingsAsync(Guid aCompanyId, Guid aVehicleId, CancellationToken aCancelToken = default(CancellationToken))
{
if (aCompanyId == Guid.Empty)
throw new ArgumentException(nameof(GetStuffListForThingsAsync) + " Company GUID is Empty");
if (aVehicleId == Guid.Empty)
throw new ArgumentException(nameof(GetStuffListForThingsAsync) + " Vehicle GUID is Empty");
IList<StuffDto> allPresc = await GetStuffListAsync(aCompanyId, aCancelToken);
List<StuffDto> res = new List<StuffDto>();
foreach (StuffDto prescr in allPresc)
{
ThingsDetailsDto vehicle = prescr.vehicleDetails.FirstOrDefault(t => t.vehicleId == aVehicleId);
if (vehicle != null)
{
// Clones the Stuff...
ISerializationInterface serializer = new SerializationJson();
string tmpString = serializer.Serialize(prescr);
StuffDto newPrescr = serializer.Deserialize<StuffDto>(tmpString);
// Remove all the vehicles
newPrescr.vehicleDetails.Clear();
// Add the vehicle found
newPrescr.vehicleDetails.Add(vehicle);
res.Add(newPrescr);
}
}
return res;
}
/*
public Task<bool> GetStuffStatusAsync(Guid aCompanyId, string aStuffId, CancellationToken aCancelToken = default(CancellationToken))
{
// This API has been marked as Optional on PostMan...
throw new NotImplementedException();
} */
}
最后，这是在代码中的用法：
IConnClient connClient = ConnClientFactory.Create();
connClient.Timeout = TimeSpan.FromMinutes(4);
//Then later in the code:
connClient.GetStuffListAsync(companyGuid);
我非常困惑的部分是connClient中的这一部分：
public ConnClient(Uri aBaseAddress, string apiKey, WebRequestHandler innerHandler = null, params DelegatingHandler[] handlers)
: base("", "", innerHandler, handlers) // DIP - IoC
看起来他们使用的是构造函数，其中innerHandler（WebRequestHandler）未使用默认值初始化，因此为null，那么如何进行Web服务调用？ 谁能帮助解释所有这些类和接口之间的连接？ 这是极其压倒性的，很难弄清这里正在发生什么...
2 个解决方案
解决方案1
5 已采纳 2016-06-15 22:29:50
我认为对解释器链的解释将在这里帮助您更好地理解。
public outsideClass(params DelegatingHandler[] handlers) : this(null, handlers) { }
这是outsideClass的第一个构造函数。 请注意，它没有主体，但更重要的是这一部分： this(null, handlers) 。 构造函数的这一部分说：“首先，调用具有两个参数的OTHER构造函数，然后再做一些额外的工作”。 但是，在这种情况下，没有多余的东西。
所以
public outsideClass(params DelegatingHandler[] handlers) : this(null, handlers) { }
电话
public outsideClass(WebRequestHandler innerHandler, params DelegatingHandler[] handlers) : this("", "", innerHandler, handlers) { }
哪个电话
public outsideClass(string aUser, string aPass, WebRequestHandler innerHandler, params DelegatingHandler[] handlers) : this(aUser, aPass, null, innerHandler, handlers) { }
最终调用具有所有逻辑的“主”构造函数。
public outsideClass(string aUser, string aPass, Uri aBaseAddress, WebRequestHandler innerHandler, params DelegatingHandler[] handlers){ ... }
之所以这样构造构造函数，是为了减少代码重复，并确保如果必须更改构造函数逻辑，则可以成功更改它们。
接下来，让我们看看ConnClient 。 它的构造函数看起来像
public ConnClient(Uri aBaseAddress, string apiKey, WebRequestHandler innerHandler = null, params DelegatingHandler[] handlers)
: base("", "", innerHandler, handlers) // DIP - IoC
与outsideClass相似，但是它具有this(...) ，而不是base("", "", innerHandler, handlers) 。 base函数非常像this ，但是它没有在SAME类中调用另一个构造函数，而是在BASE类中调用了一个构造函数。
所以，
public ConnClient(Uri aBaseAddress, string apiKey, WebRequestHandler innerHandler = null, params DelegatingHandler[] handlers)
: base("", "", innerHandler, handlers) // DIP - IoC
电话
public outsideClass(string aUser, string aPass, WebRequestHandler innerHandler, params DelegatingHandler[] handlers) : this(aUser, aPass, null, innerHandler, handlers) { }
再次调用您的“主要”构造函数！
public outsideClass(string aUser, string aPass, Uri aBaseAddress, WebRequestHandler innerHandler, params DelegatingHandler[] handlers){ ... }
最后，回答关于接口的问题。 在代码中使用它们的原因有很多。 最大的好处是，它们可以使您的所有此类消费者与实际的消费者脱钩。 这意味着，如果将来要更改实现，则可以避免重新设计所有使用者以及代码本身的麻烦。
想想一个示例，您正在编写一个库来处理数据库。 您有一个MySqlDatabaseAdapater类。 如果所有代码都使用MySqlDatabaseAdapter ，并且您决定更改为OracleDatabaseAdapter ，则必须使用MySqlDatabaseAdapter进行所有更改！ 但是，如果用实现接口的MySqlDatabaseAdapter安排代码，则IDatabaseAdapter和所有使用的代码都引用IDatabaseAdapter ，现在您可以用OracleDatabaseAdapater替换使用者，ALSO也实现IDatabaseAdapter ，您需要更改的代码少得多！
另一个好处是测试代码。 如果您有一个进行网络活动的类（类似于此类），并且想要对使用该类的代码进行单元测试，则您的单元测试将进行网络活动。 不好！ 但是，如果您使用接口方法，则可以设置测试，以为要测试的代码提供一个假冒的IConnClient ，该假冒产品可假冒网络，但实际上并非如此。 这使您可以编写可靠，可预测且快速的测试。
希望这可以帮助！
解决方案2
1 2016-06-16 01:24:07
这不是一个完整的答案，但是我不能在注释中放入格式化的代码。
这就是为什么即使在构造函数中innerHandler为null， outsideClass也可以工作的原因：
if (innerHandler == null)
{
innerHandler = CreateDefaultMessageHandler();
}
另外，此行末尾的注释可能会揭示以下内容：
public ConnClient(Uri aBaseAddress, string apiKey, WebRequestHandler innerHandler = null, params DelegatingHandler[] handlers)
: base("", "", innerHandler, handlers) // DIP - IoC
我怀疑DIP - IoC可能是对依赖项注入容器（有时也称为“ IoC容器”）的引用。这意味着项目可能正在使用DI容器，例如Unity，Windsor，Autofac或类似的东西。 您可能会在项目中看到对其中之一的引用。 如果是这样，那可能可以解释接口的特殊用法。 典型的模式是
- 定义接口
- 定义实现接口的类
- 使其他类依赖于接口（而不是类）
- 配置DI容器，以便如果类依赖于接口，则该容器将创建该类的实例。
那不是对依赖注入的一个很好的解释，但是如果这种猜测是正确的，那么它可能会帮助您找到一些代码，这些代码指示向所有这些构造函数提供什么值。
基类中的派生实例
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