用来获取网页的类（转！vb.net参考）

转自http://www.cnblogs.com/squirrel_sc/archive/2004/09/26/46762.aspx
Imports System.Net


Imports System.IO






Public Class HttpDriverClass HttpDriver






Public Function GetPage()Function GetPage(ByVal url As String, Optional ByRef postPara As String = "", Optional ByRef encType As String = "GB2312") As String


Return GetPage(url, postPara, Nothing, False, encType)


End Function






Public Function GetPage()Function GetPage(ByVal url As String, ByRef postPara As System.Collections.Hashtable, Optional ByRef encType As String = "GB2312") As String


Return GetPage(url, ColToStr(postPara), encType)


End Function






Public Function GetPage()Function GetPage(ByVal url As String, ByRef postPara As String, ByRef cookies As CookieCollection, ByVal hasCookie As Boolean, Optional ByRef encType As String = "GB2312", Optional ByRef refer As String = "") As String


If (url.StartsWith("http://") = False) Then


url = "http://" & url


End If


Dim hRqst As HttpWebRequest = HttpWebRequest.Create(url)


If (hasCookie = True AndAlso (Not cookies Is Nothing)) Then


hRqst.CookieContainer = New CookieContainer


hRqst.CookieContainer.Add(cookies)


End If




hRqst.ContentType = "application/x-www-form-urlencoded"


hRqst.Headers.Add("Accept-Language", "zh-cn")


Dim streamData As Stream


Dim bt() As Byte


If (postPara = "") Then


hRqst.Method = "GET"


Else


hRqst.Method = "POST"


hRqst.AllowWriteStreamBuffering = True


bt = System.Text.Encoding.ASCII.GetBytes(postPara)


hRqst.ContentLength = bt.Length


hRqst.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"


hRqst.Referer = refer


hRqst.KeepAlive = False


hRqst.Timeout = 20000


streamData = hRqst.GetRequestStream()


streamData.Write(bt, 0, bt.Length)


streamData.Close()


End If


Dim hRsp As HttpWebResponse


hRsp = hRqst.GetResponse()


streamData = hRsp.GetResponseStream()


If (hasCookie = True AndAlso (Not hRsp.Cookies Is Nothing)) Then


cookies.Add(hRsp.Cookies)


End If


If (encType = "") Then


encType = "GB2312"


End If


Dim readStream As New IO.StreamReader(streamData, System.Text.Encoding.GetEncoding(encType))


GetPage = readStream.ReadToEnd()


streamData.Close()


End Function






Public Function GetPage()Function GetPage(ByVal url As String, ByRef postPara As System.Collections.Hashtable, ByRef cookies As CookieCollection, ByVal hasCookie As Boolean, Optional ByRef encType As String = "GB2312") As String


Return GetPage(url, ColToStr(postPara), cookies, True, encType)


End Function






Public Function GetPage()Function GetPage(ByVal url As String, ByRef cookies As CookieCollection, ByVal hasCookie As Boolean, Optional ByRef encType As String = "GB2312") As String


Return GetPage(url, "", cookies, True, encType)


End Function




'该函数用于转换表单项集合为字符串




Public Shared Function ColToStr()Function ColToStr(ByRef ht As System.Collections.Hashtable, Optional ByRef encType As String = "GB2312") As String


Dim str As String


Dim para As DictionaryEntry


For Each para In ht


str &= System.Web.HttpUtility.UrlEncode(CType(para.Key, String), Text.Encoding.GetEncoding(encType))


str &= "="


str &= System.Web.HttpUtility.UrlEncode(CType(para.Value, String), Text.Encoding.GetEncoding(encType))


str &= "&"


Next


str = str.Substring(0, str.Length - 1)


Return str


End Function




End Class



如果需要支持cookie，并支持refer，可以通过下面这个类来使用上面的httpdriver。


'该类用于访问含有cookie的页面


Imports System.IO






Public Class UserAgentClass UserAgent


Private m_cookies As New System.Net.CookieCollection


Private refer As String


Private hd As New HttpDriver






Public Function GetPage()Function GetPage(ByVal url As String, Optional ByRef postPara As String = "", Optional ByRef encType As String = "GB2312") As String


GetPage = hd.GetPage(url, postPara, m_cookies, True, encType, refer)


refer = url


End Function






Public Function GetPage()Function GetPage(ByVal url As String, ByRef postPara As Hashtable, Optional ByRef encType As String = "GB2312") As String


Return GetPage(url, hd.ColToStr(postPara), encType)


End Function






Public Function SetCookie()Function SetCookie(ByVal cookies As System.Net.CookieCollection)


m_cookies = cookies


End Function






Public Function GetCookie()Function GetCookie() As System.Net.CookieCollection


Return m_cookies


End Function


End Class



轻量的get网页的函数




Public Function GetPage()Function GetPage(ByVal url As String) As String


Dim hRqst As HttpWebRequest = HttpWebRequest.Create(url)




hRqst.ContentType = "application/x-www-form-urlencoded"


hRqst.Method = "GET"


Dim streamData As Stream




Dim hRsp As HttpWebResponse = hRqst.GetResponse()


streamData = hRsp.GetResponseStream()




Dim readStream As New IO.StreamReader(streamData, System.Text.Encoding.GetEncoding("GB2312"))


GetPage = readStream.ReadToEnd()


streamData.Close()


End Function



Get方法：


Dim ua as New UserAgent


Dim content as String


Dim url as String


url = "www.sina.com.cn"


content = ua.GetPage(url)



Post方法：


Dim ua as New UserAgent


Dim content as String


Dim url as String


Dim ht as New HashTable




url = "mail.sina.com.cn"


ht.Add("username", "用户名")


ht.Add("password", "密码")


content = ua.GetPage(url, ht)