VB.net 获取网络时间

一、首先建立正则表达式

 ''' <summary>    ''' 正则表达式(ByVal 被检字符, 检索规则 strng)    ''' </summary>    ''' <param name="patrn">被检字符</param>    ''' <param name="strng">检索规则</param>    ''' <returns>检索到的位置</returns>    ''' <remarks></remarks>    Public Function RegExp(ByVal patrn, ByVal strng)        Dim regEx, Match, Matches, RetStr ' 建立变量。         RetStr = Nothing        regEx = New VBScript_RegExp_55.RegExp    ' 建立正则表达式。              regEx.Pattern = patrn   ' 设置模式。                regEx.IgnoreCase = True   ' 设置是否区分大小写。               regEx.Global = True   ' 设置全局替换。                Matches = regEx.Execute(strng) ' 执行搜索。                For Each Match In Matches  ' 遍历 Matches 集合。                       RetStr = Match.Value        Next        Return RetStr    End Function

二、建立一个获取网页源码的函数

''' <summary>    ''' 获得网页信息(网址 As String) As String    ''' </summary>    ''' <param name="strURL">网址</param>    ''' <returns>获得网页信息</returns>    ''' <remarks></remarks>    Public Function GetWebText(strURL As String) As String        On Error Resume Next        Dim url As String = strURL        Dim httpReq As System.Net.HttpWebRequest        httpReq.ServicePoint.ConnectionLimit = 255        Dim httpResp As System.Net.HttpWebResponse        Dim httpURL As New System.Uri(url)        httpReq = CType(Net.HttpWebRequest.Create(httpURL), Net.HttpWebRequest)        httpReq.Method = "GET"        httpResp = CType(httpReq.GetResponse(), Net.HttpWebResponse)        httpReq.KeepAlive = False ' 获取或设置一个值，该值指示是否与Internet资源建立持久连接。        Dim reader As IO.StreamReader = New IO.StreamReader(httpResp.GetResponseStream, System.Text.Encoding.GetEncoding("GB2312"))    '用GB2312字符        Dim respHTML As String = reader.ReadToEnd() 'respHTML就是网页源代码         Dim myip As String = ""        Dim myPort = ""        httpResp.Close()        If respHTML <> "" Then            url = ""            myip = ""            myPort = ""        End If        Return respHTML    End Function

三、建立获取网络时间的函数

   '获得网络时间    ''' <summary>    ''' 网络时间()    ''' </summary>    ''' <param name="Style">定义时间格式</param>    ''' <returns>网络时间</returns>    ''' <remarks></remarks>    Function GetWebTime(Optional Style As Microsoft.VisualBasic.DateFormat = Nothing) As String        Dim WebText = GetWebText("http://open.baidu.com/special/time/")'从百度的北京时间获取页面源码               Dim regexp As New RegularExpressions        Dim WebTimes As String = RegExp("[0-9]{13}", WebText)'获取源码中时间信息        Dim WebTime As Date = #1/1/1970 8:00:00 AM#'定义初始时间        WebTime = DateAdd(DateInterval.Second, WebTimes / 1000, WebTime)'换算成现在的时间        If Style = Nothing Then'根据时间格式参数返回不同格式的时间信息            Return WebTime        Else            Return Format(WebTime, Style)        End If    End Function