Question

我有一个WCF服务作为代理，调用WebClient返回一个字符串。 WebClient正在查询令牌服务，其中用户名和密码通过https发送。如果用户名和密码正确，则该服务正常工作，但是如果用户名和密码无效，则WebClient会抛出异常（403 Forbidden），该异常在下面的代码中是预期和处理的。然而，WCF服务然后继续挂起，直到它超时，我无法弄清楚原因。

Public Function GetToken(un As String, pw As String, ref As String) As TokenResult Implements IAGSAuthentication.GetToken

        Dim Token As String
        Dim TokenURL As String = String.Format("https://server/arcgisserver/tokens?request=getToken&username={0}&password={1}&timeout={2}", un, pw, Timeout)
        Dim tokenResult As TokenResult = New TokenResult
        If TokenService.IsBusy = False Then

            Try
                Token = TokenService.DownloadString(New Uri(TokenURL))
                tokenResult.Token = Token
                Return tokenResult
                Exit Function
            Catch ANEx As ArgumentNullException
                TokenService.Dispose()
                tokenResult.TokenException = ANEx
                Return tokenResult
                Exit Function
            Catch WEx As WebException
                TokenService.Dispose()
                tokenResult.TokenException = WEx
                Return tokenResult
                Exit Function
            Catch CEx As CommunicationException
                TokenService.Dispose()
                tokenResult.TokenException = CEx
                Return tokenResult
                Exit Function
            Catch Ex As Exception
                TokenService.Dispose()
                tokenResult.TokenException = Ex
                Return tokenResult
                Exit Function
            End Try

        End If
        Return tokenResult
    End Function

我还应该补充说，当我调试WCF参考文件时，在自动填充的客户端方法中显示异常。

Public Function EndGetToken(ByVal result As System.IAsyncResult) As AuthServiceRef.TokenResult Implements AuthServiceRef.AuthService.EndGetToken
                Dim _args((0) - 1) As Object
                Dim _result As AuthServiceRef.TokenResult = CType(MyBase.EndInvoke("GetToken", _args, result),AuthServiceRef.TokenResult)
                Return _result
            End Function

我的想法是，我认为通过处理WCF服务中的异常并在自定义类中返回异常，我可以将异常推送给用户而没有运行时问题。以下是客户端捕获的异常：

System.ServiceModel.CommunicationException was unhandled by user code

Message =远程服务器返回错误：NotFound。堆栈跟踪：在System.ServiceModel.AsyncResult.End [TAsyncResult]（IAsyncResult结果）在System.ServiceModel.Channels.ServiceChannel.EndCall（String action，Object [] outs，IAsyncResult result）在System.ServiceModel.ClientBase 1.ChannelBase 1.EndInvoke（String methodName，Object [] args，IAsyncResult result）在MatrixWebMap.AuthServiceRef.AuthServiceClient.AuthServiceClientChannel.EndGetToken（IAsyncResult结果）在MatrixWebMap.AuthServiceRef.AuthServiceClient.AuthServiceRef_AuthService_EndGetToken（IAsyncResult结果）在MatrixWebMap.AuthServiceRef.AuthServiceClient.OnEndGetToken（IAsyncResult结果）在System.ServiceModel.ClientBase`1.OnAsyncCallCompleted（IAsyncResult结果） InnerException：System.Net.WebException Message =远程服务器返回错误：NotFound。堆栈跟踪：在System.Net.Browser.AsyncHelper.BeginOnUI（SendOrPostCallback beginMethod，Object state）在System.Net.Browser.BrowserHttpWebRequest.EndGetResponse（IAsyncResult asyncResult） at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelAsyncRequest.CompleteGetResponse（IAsyncResult result） InnerException：System.Net.WebException Message =远程服务器返回错误：NotFound。堆栈跟踪：在System.Net.Browser.BrowserHttpWebRequest.InternalEndGetResponse（IAsyncResult asyncResult）在System.Net.Browser.BrowserHttpWebRequest。＆lt;＆gt; c_ DisplayClassa.b _9（Object sendState）在System.Net.Browser.AsyncHelper。＆lt;＆gt; c_ DisplayClass4.b _0（Object sendState） InnerException：

Answer 1

因此，从我收集的事件中，当我将异常添加到TokenResult类并返回它时，WCF响应出现了exception属性的问题。解决方法是在响应之前处理异常，并使TokenException成为在返回结果之前创建的字符串。

因此，对于'403 Forbidden'网络异常，我只是构造了一个字符串并返回“”您输入的信息与我们的记录不符。请再试一次。“有点肮脏的工作，但它非常适合我在这里尝试做的事情。

            Try
                Token = TokenService.DownloadString(New Uri(TokenURL))
                tokenResult.Token = Token
                Return tokenResult
                Exit Function

            Catch ANEx As ArgumentNullException                
                tokenResult.TokenException = ANEx.Message
                Return tokenResult
                Exit Function

            Catch WEx As WebException                   
                If WEx.Status = WebExceptionStatus.ProtocolError Then
                    tokenResult.TokenException = "The information you have entered does not match our records. Please try again."
                Else
                    tokenResult.TokenException = WEx.Message
                End If
                Return tokenResult
                Exit Function

            Catch CEx As CommunicationException      
                tokenResult.TokenException = CEx.Message
                Return tokenResult
                Exit Function

            Catch Ex As Exception                    
                tokenResult.TokenException = Ex.Message
                Return tokenResult
                Exit Function
            End Try

如果WebClient返回异常，WCF服务会超时

1 个答案: