vb.net用来获取网页的类

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,ColToStr(postPara),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,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,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,Text.Encoding.GetEncoding(encType))
str &= "&"
Next
str = str.Substring(0,str.Length - 1)
Return str
End Function

End Class

’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 encType As String = "GB2312") As String
GetPage = hd.GetPage(url,m_cookies,encType,refer)
refer = url
End Function

Public Function GetPage()Function GetPage(ByVal url As String,ByRef postPara As Hashtable,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

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

Dim ua as New UserAgent
Dim content as String
Dim url as String
url = "www.sina.com.cn"
content = ua.GetPage(url)

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)