我正在使用 W3C 验证服务来检查我在 TextBox 中键入的文本是否是有效的标记。
它几乎可以工作了。但是，在特定条件下，我的输入会导致错误，然后是无休止的超时异常。我必须关闭重新打开程序才能让它再次工作。
请浏览我的代码并帮助我解决这个问题。
我有一个带有 TextBox 和 StatusBar 的非常简单的 WPF 应用程序。当我输入时，状态栏会更新，让我知道我输入的标记是否有效。因此，我不会敲击服务，仅在没有击键的情况下经过一秒钟或更长时间后才会进行验证。
无效 http://img9.imageshack.us/img9/3788/invalidr.gif
它的状态栏可能会显示：“正在验证...”、“有效”、“无效”，或者——如果有的话——异常的消息。
验证 http://img7.imageshack.us/img7/5842/validating.gif
以下验证成功：
XHTML 输入
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xml:lang="en">
<head>
<title>Test</title>
</head>
<body>
<h1>Test</h1>
<p>This is a test</p>
</body>
</html>
如果我像这样打破我的段落，<p>This is a test</那么在尝试处理响应 XML 时会出现此异常：
名称不能以 '"' 字符开头，十六进制值 0x22。第 86 行，位置 40。
XML 异常 http://img11.imageshack.us/img11/3066/namecannotbegin.gif
如果验证连续两次失败，那么我似乎不能只修复我的段落标签并像往常一样继续。由于某种原因，每个后续验证都会失败，并出现以下异常：
操作已超时
超时 http://img21.imageshack.us/img21/7600/timedout.gif
这很奇怪。
很抱歉发布我的整个项目，但我不知道我的问题来自哪里。可能是我的线程、Web 服务通信、异常处理......我似乎找不到它。我是否正确关闭了我的 StreamWriter、HttpWebRequest 和 ResponseStreams？
XAML
<Window x:Class="Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="W3C Validation"
Height="300"
Width="300"
Name="Window1">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<TextBox Grid.Row="0"
TextWrapping="Wrap"
AcceptsReturn="True"
VerticalScrollBarVisibility="Visible"
FontFamily="Consolas"
TextChanged="TextBox_TextChanged" />
<StatusBar Grid.Row="1">
<StatusBarItem>
<TextBlock x:Name="TextBlockResult" />
</StatusBarItem>
</StatusBar>
</Grid>
</Window>
视觉基础
Imports System.ComponentModel
Imports <xmlns:env="http://www.w3.org/2003/05/soap-envelope">
Imports <xmlns:m="http://www.w3.org/2005/10/markup-validator">
Class Window1
Private WithEvents Worker As BackgroundWorker
Private _WorkerArgument As String
Private Sub Window1_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
InitializeWorker()
End Sub
Private Sub InitializeWorker()
Worker = New BackgroundWorker
Worker.WorkerSupportsCancellation = True
AddHandler Worker.DoWork, AddressOf Worker_DoWork
AddHandler Worker.RunWorkerCompleted, AddressOf Worker_RunWorkerCompleted
End Sub
Private Sub TextBox_TextChanged(ByVal sender As System.Object, ByVal e As System.Windows.Controls.TextChangedEventArgs)
TryToWork(DirectCast(sender, TextBox).Text)
End Sub
Sub TryToWork(ByVal Argument As String)
If _WorkerArgument IsNot Nothing Then
_WorkerArgument = Argument
Exit Sub
End If
If Not Worker.IsBusy Then
TextBlockResult.Text = "Validating..."
Worker.RunWorkerAsync(Argument)
Exit Sub
End If
_WorkerArgument = Argument
Worker.CancelAsync()
Dim RetryTimer As New Windows.Threading.DispatcherTimer
AddHandler RetryTimer.Tick, AddressOf RetryTicker
RetryTimer.Interval = New TimeSpan(1) '1 tick'
RetryTimer.Start()
End Sub
Sub RetryTicker(ByVal sender As Object, ByVal e As System.EventArgs)
If Not Worker.IsBusy Then
DirectCast(sender, Windows.Threading.DispatcherTimer).Stop()
TextBlockResult.Text = "Validating..."
Worker.RunWorkerAsync(_WorkerArgument)
_WorkerArgument = Nothing
End If
End Sub
Private Sub Worker_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs)
'wait for one second'
Dim StartTime As DateTime = DateTime.Now()
While Now.Subtract(StartTime) < New TimeSpan(0, 0, 1)
If DirectCast(sender, BackgroundWorker).CancellationPending Then
e.Cancel = True
Exit Sub
End If
System.Threading.Thread.Sleep(New TimeSpan(0, 0, 0, 0, 100)) 'tenth of a second'
End While
'then validate'
e.Result = Validate(DirectCast(e.Argument, String))
End Sub
Private Function Validate(ByVal Text As String) As String
Try
Dim Url As String = "http://validator.w3.org/check"
Dim Post As String = "&fragment=" + Web.HttpUtility.UrlEncode(Text) + "&output=soap12"
Dim ResponseDocument As XDocument = XDocument.Load(New Xml.XmlTextReader(Communicate(Url, Post)))
If ResponseDocument.Root.<env:Body>.<m:markupvalidationresponse>.<m:validity>.Value = "true" Then
Return "Valid"
Else
Return "Invalid"
End If
Catch ex As Exception
Return ex.Message
End Try
End Function
Private Function Communicate(ByVal Url As String, ByVal Post As String) As System.IO.Stream
Dim Writer As System.IO.StreamWriter = Nothing
Dim Request As System.Net.HttpWebRequest = System.Net.WebRequest.Create(Url)
Request.Method = "POST"
Request.ContentLength = Post.Length
Request.ContentType = "application/x-www-form-urlencoded"
Request.Timeout = 2000 '2 seconds'
Try
Writer = New System.IO.StreamWriter(Request.GetRequestStream())
Writer.Write(Post)
Catch
Finally
If Not Writer Is Nothing Then
Writer.Close()
End If
End Try
Return Request.GetResponse.GetResponseStream()
End Function
Private Sub Worker_RunWorkerCompleted(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs)
If Not e.Cancelled Then
TextBlockResult.Text = DirectCast(e.Result, String)
End If
End Sub
End Class
谢谢你的帮助！