我已經實現了IErrorHandler來處理在我寧靜的WCF服務的構造函數中拋出的授權異常。當遇到一般異常時,我的自定義類型按預期返回,但ContentType標頭不正確。當HTTP狀態代碼是401時,IErrorHandler返回錯誤的消息正文未授權
HTTP/1.1 500 Internal Server Error
Content-Type: application/xml;
...
{"ErrorMessage":"Error!"}
然而,當錯誤處理程序試圖返回一個401未授權的HTTP狀態代碼消息體被覆蓋到默認類型但ContentType標頭是理所應當的。
HTTP/1.1 401 Unauthorized
Content-Type: application/json;
...
{"Message":"Authentication failed.","StackTrace":null,"ExceptionType":"System.InvalidOperationException"}
很明顯這裏有些問題,但我不確定是什麼。
我該如何實現IErrorHandler,使其返回帶有正確標題的json中的自定義類型?
BaseDataResponseContract對象:
[Serializable]
[DataContract(Name = "BaseDataResponseContract")]
public class BaseDataResponseContract
{
[DataMember]
public string ErrorMessage { get; set; }
} // end
這是我想要返回的對象。我的應用程序中的所有其他對象都從此對象繼承。當拋出異常時,我們真正關心的是http狀態碼和錯誤信息。
IErrorHandler實施(未顯示以表簡明日誌記錄):
namespace WebServices.BehaviorsAndInspectors
{
public class ErrorHandler : IErrorHandler
{
public bool HandleError(Exception error)
{
return true;
} // end
public void ProvideFault(Exception ex, MessageVersion version, ref Message fault)
{
// Create a new instance of the object I would like to return with a default message
var baseDataResponseContract = new BaseDataResponseContract { ErrorMessage = "Error!" };
// Get the outgoing response portion of the current context
var response = WebOperationContext.Current.OutgoingResponse;
// Set the http status code
response.StatusCode = HttpStatusCode.InternalServerError;
// If the exception is a specific type change the default settings
if (ex.GetType() == typeof(UserNotFoundException))
{
baseDataResponseContract.ErrorMessage = "Invalid Username!";
response.StatusCode = HttpStatusCode.Unauthorized;
}
// Create the fault message that is returned (note the ref parameter)
fault = Message.CreateMessage(version, "", baseDataResponseContract, new DataContractJsonSerializer(typeof(BaseDataResponseContract)));
// Tell WCF to use JSON encoding rather than default XML
var webBodyFormatMessageProperty = new WebBodyFormatMessageProperty(WebContentFormat.Json);
fault.Properties.Add(WebBodyFormatMessageProperty.Name, webBodyFormatMessageProperty);
// Add ContentType header that specifies we are using json
var httpResponseMessageProperty = new HttpResponseMessageProperty();
httpResponseMessageProperty.Headers[HttpResponseHeader.ContentType] = "application/json";
fault.Properties.Add(HttpResponseMessageProperty.Name, httpResponseMessageProperty);
} // end
} // end class
} // end namespace
IServiceBehavior接口實現:
namespace WebServices.BehaviorsAndInspectors
{
public class ErrorHandlerExtensionBehavior : BehaviorExtensionElement, IServiceBehavior
{
public override Type BehaviorType
{
get { return GetType(); }
}
protected override object CreateBehavior()
{
return this;
}
private IErrorHandler GetInstance()
{
return new ErrorHandler();
}
void IServiceBehavior.AddBindingParameters(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase, Collection<ServiceEndpoint> endpoints, BindingParameterCollection bindingParameters) { } // end
void IServiceBehavior.ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
{
var errorHandlerInstance = GetInstance();
foreach (ChannelDispatcher dispatcher in serviceHostBase.ChannelDispatchers)
{
dispatcher.ErrorHandlers.Add(errorHandlerInstance);
}
}
void IServiceBehavior.Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase) { } // end
} // end class
} // end namespace
的Web.Config:
<system.serviceModel>
<services>
<service name="WebServices.MyService">
<endpoint binding="webHttpBinding" contract="WebServices.IMyService" />
</service>
</services>
<extensions>
<behaviorExtensions>
<!-- This extension if for the WCF Error Handling-->
<add name="ErrorHandlerBehavior" type="WebServices.BehaviorsAndInspectors.ErrorHandlerExtensionBehavior, WebServices, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
</behaviorExtensions>
</extensions>
<behaviors>
<serviceBehaviors>
<behavior>
<serviceMetadata httpGetEnabled="true"/>
<serviceDebug includeExceptionDetailInFaults="true"/>
<ErrorHandlerBehavior />
</behavior>
</serviceBehaviors>
</behaviors>
....
</system.serviceModel>
最後,我看到類似的行爲當使用WebFaultException。我的想法是,這是一些深埋的.Net神祕人的結果。我選擇實現IErrorHandler,以便可以捕獲任何其他可能無法處理的異常。
參考:
https://msdn.microsoft.com/en-us/library/system.servicemodel.dispatcher.ierrorhandler(v=vs.100).aspx
其他實例:
IErrorHandler doesn't seem to be handling my errors in WCF .. any ideas?
How to make custom WCF error handler return JSON response with non-OK http code?
How do you set the Content-Type header for an HttpClient request?
是的......但如何?我得到了與WebOperationContext.current.OutgoingResponse相同的progrem,但我沒有Write方法,所以如何進行自定義響應? – DestyNova