為 WCF 服務實現 IErrorHandler
為 WCF 服務實現 IErrorHandler 是集中錯誤處理和日誌記錄的好方法。此處顯示的實現應該捕獲由於呼叫你的某個 WCF 服務而引發的任何未處理的異常。此示例中還顯示瞭如何返回自定義物件，以及如何返回 JSON 而不是預設 XML。
實現 IErrorHandler：
using System.ServiceModel.Channels;
using System.ServiceModel.Dispatcher;
using System.Runtime.Serialization.Json;
using System.ServiceModel;
using System.ServiceModel.Web;
namespace BehaviorsAndInspectors
{
public class ErrorHandler : IErrorHandler
{
public bool HandleError(Exception ex)
{
// Log exceptions here
return true;
} // end
public void ProvideFault(Exception ex, MessageVersion version, ref Message fault)
{
// Get the outgoing response portion of the current context
var response = WebOperationContext.Current.OutgoingResponse;
// Set the default http status code
response.StatusCode = HttpStatusCode.InternalServerError;
// Add ContentType header that specifies we are using JSON
response.ContentType = new MediaTypeHeaderValue("application/json").ToString();
// Create the fault message that is returned (note the ref parameter) with BaseDataResponseContract
fault = Message.CreateMessage(
version,
string.Empty,
new CustomReturnType { ErrorMessage = "An unhandled exception occurred!" },
new DataContractJsonSerializer(typeof(BaseDataResponseContract), new List<Type> { typeof(BaseDataResponseContract) }));
if (ex.GetType() == typeof(VariousExceptionTypes))
{
// You might want to catch different types of exceptions here and process them differently
}
// Tell WCF to use JSON encoding rather than default XML
var webBodyFormatMessageProperty = new WebBodyFormatMessageProperty(WebContentFormat.Json);
fault.Properties.Add(WebBodyFormatMessageProperty.Name, webBodyFormatMessageProperty);
} // end
} // end class
} // end namespace
在此示例中，我們將處理程式附加到服務行為。你也可以以類似的方式將此附加到 IEndpointBehavior，IContractBehavior 或 IOperationBehavior。
附加到服務行為：
using System;
using System.Collections.ObjectModel;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Configuration;
using System.ServiceModel.Description;
using System.ServiceModel.Dispatcher;
namespace BehaviorsAndInspectors
{
public class ErrorHandlerExtension : 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
Web.config 中的配置：
...
<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>
...
以下是一些可能對此主題有幫助的連結：
https://msdn.microsoft.com/en-us/library/system.servicemodel.dispatcher.ierrorhandler(v=vs.100).aspx
其他例子：
當 HTTP 狀態程式碼為 401 Unauthorized 時，IErrorHandler 返回錯誤的訊息體
IErrorHandler 似乎沒有處理我在 WCF 中的錯誤..任何想法？