Question

我调用的方法可能会在覆盖的函数中抛出异常。如果MyBase.GetWebResponse()抛出异常，我怎么能从主代码中捕获它？调试器在GetWebResponse停止，而不是在主Try。

我使用覆盖函数来获取重定向的ResponseUri。不使用GetWebResponse，我可以捕获异常。

主要代码：

Try
    RetryAction(Sub()
                    Using cawc As New CookieAwareWebClient)
                        strContent = cawc.DownloadString(m_url)
                        m_url = cawc.ResponseUri.ToString
                    End Using
                End Sub, 10, 1000)
Catch ex As WebException
    StreamNotAvailable(ex)
End Try

功能：

Public Sub RetryAction(action As Action, numRetries As Integer, retryTimeout As Integer)
        If action Is Nothing Then
            Throw New ArgumentNullException("action")
        End If
        ' slightly safer...
        Do
            Try
                action()
                Exit Sub
            Catch
                If numRetries <= 0 Then
                    Throw
                Else
                    ' improved to avoid silent failure
                    Thread.Sleep(retryTimeout)
                End If
            End Try
        Loop While Interlocked.Decrement(numRetries) > -1
    End Sub

类别：

Public Class CookieAwareWebClient
    Inherits WebClient

    ...

    Private m_ResponseUri As Uri
    Public ReadOnly Property ResponseUri() As Uri
        Get
            Return m_ResponseUri
        End Get
    End Property

    Protected Overrides Function GetWebResponse(request As WebRequest) As WebResponse
            Dim response As HttpWebResponse = MyBase.GetWebResponse(request)
            m_ResponseUri = response.ResponseUri
            Return response
    End Function
End Class

Answer 1

我终于找到了解决方案：

Try
    RetryAction(Sub()
                    Try
                        Using cawc As New CookieAwareWebClient)
                            strContent = cawc.DownloadString(m_url)
                            m_url = cawc.ResponseUri.ToString
                        End Using
                    Catch ex As Exception
                        Throw
                    End Try
                End Sub, 10, 1000)
Catch ex As WebException
    StreamNotAvailable(ex)
End Try

处理从覆盖函数抛出的异常

1 个答案: