我试图弄清楚一个更高级的开发人员编写的代码是如何工作的，我对此感到非常困惑。我希望有人可以帮助我理解这个项目中存在的所有不同的类和接口。
我有一个外部类存在于类库dll中，与我正在编辑的Web应用程序分开。我们把它称为OutsideClass。我无法弄清楚为什么这个类有这么多的构造函数，以及如何进行请求，因为只有一个构造函数有一个默认的WebRequestHandler而其余的没有。在Web应用程序中，此类的实例初始化，WebRequestHandler为null！这让我发疯了......这是外面的课程：
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（为什么需要这个，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);
}
这是令我困惑的代码，在Web应用程序中找到，有一个IConnClient和一个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，这是它在代码中的使用方式：
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
看起来他们正在使用一个构造函数，其中innerHandler（WebRequestHandler）没有使用默认值初始化，因此为null，那么如何进行Web服务调用呢？任何人都可以帮助解释所有这些类和接口之间的连接吗？这是非常压倒性的，很难弄清楚这里发生了什么......
答案 0 :(得分：5)
我认为对构造符链接的解释会在这里帮助你理解。
public outsideClass(params DelegatingHandler[] handlers) : this(null, handlers) { }
这是outsideClass的第一个构造函数。请注意，它没有正文，但更重要的是这部分：this(null, handlers)。构造函数的这一部分说'首先，调用我的OTHER构造函数，它接受两个参数，然后做一些额外的东西'。但是，在这种情况下，没有额外的东西。
所以
public outsideClass(params DelegatingHandler[] handlers) : this(null, handlers) { }
来电
public outsideClass(WebRequestHandler innerHandler, params DelegatingHandler[] handlers) : this("", "", innerHandler, handlers) { }
调用
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'main'构造函数。
public outsideClass(string aUser, string aPass, Uri aBaseAddress, WebRequestHandler innerHandler, params DelegatingHandler[] handlers){ ... }
您构造这样的构造函数的原因是为了减少代码重复，并确保如果必须更改构造函数逻辑，则可以成功地更改它们。
接下来，让我们看一下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非常相似，但它不是this(...)，而是base("", "", innerHandler, handlers)。 base的函数与this非常相似，但它不是在SAME类中调用另一个构造函数，而是调用BASE类中的构造函数。
所以，
public ConnClient(Uri aBaseAddress, string apiKey, WebRequestHandler innerHandler = null, params DelegatingHandler[] handlers)
: base("", "", innerHandler, handlers) // DIP - IoC
来电
public outsideClass(string aUser, string aPass, WebRequestHandler innerHandler, params DelegatingHandler[] handlers) : this(aUser, aPass, null, innerHandler, handlers) { }
再次调用你的'main'构造函数！
public outsideClass(string aUser, string aPass, Uri aBaseAddress, WebRequestHandler innerHandler, params DelegatingHandler[] handlers){ ... }
最后，回答有关接口的问题。在代码中使用它们有很多原因。一些最大的好处是它们可以将您班级的任何消费者与实际班级分开。这意味着，如果您将来某个时候更改实施，您可以避免重新编写所有消费者以及代码本身。
想一个你正在编写一个库来处理数据库的例子。你有一个班级MySqlDatabaseAdapater。如果您的所有代码都使用MySqlDatabaseAdapter，并且您决定更改为OracleDatabaseAdapter，则必须使用MySqlDatabaseAdapter更改所有内容！但是，如果安排代码MySqlDatabaseAdapter实现接口，IDatabaseAdapter以及所有消费代码引用IDatabaseAdapter，现在您可以用OracleDatabaseAdapater替换您的消费者，这也是ALSO实现的IDatabaseAdapter并且您需要更少的代码才能更改！
另一个好处是测试代码。如果你有一个进行网络活动的类（这种类似的东西）并想要使用这个类的单元测试代码，那么你的单元测试将进行网络活动。不好！
但是，如果你使用接口方法，那么你可以设置你的测试来给你正在测试假冒网络的'假'IConnClient的代码，但实际上并没有。这使您可以编写可靠，可预测且快速的测试。
希望这有帮助！
答案 1 :(得分：1)
这不完全是一个答案，但我不能将格式化的代码放在评论中。
这就是outsideClass可以工作的原因，即使innerHandler在构造函数中为null：
if (innerHandler == null)
{
innerHandler = CreateDefaultMessageHandler();
}
此外，此行末尾的评论可能会显示：
public ConnClient(Uri aBaseAddress, string apiKey, WebRequestHandler innerHandler = null, params DelegatingHandler[] handlers)
: base("", "", innerHandler, handlers) // DIP - IoC
我怀疑DIP - IoC可能是对依赖注入容器的引用（有时也称为“IoC容器”）。这意味着项目可能正在使用像Unity，Windsor，Autofac或者DI容器这样的容器。相似的东西。您可能会看到对项目中其中一个的引用。如果是这样，那可能解释了接口的特定用途。
这不是依赖注入的一个很好的解释，但如果猜测正确，那么它可能会帮助你找到一些代码来指示为所有这些构造函数提供的值。