这是在博客园上看到的一篇文章,觉得不错,先帖上来。
这个经过测试,使用上比较稳定,因为考虑到统一的错误处理,类里面没有catch任何错误,所有网络错误都在使用的时候捕获,以便决定重试或终止。支持get和post,支持自定义编码,支持cookie,但不支持上传文件。
Imports System.Net
Imports System.IO
Public Class HttpDriver
Public 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(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(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) Then
cookies = 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(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(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(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
Imports System.IO
Public Class HttpDriver
Public 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(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(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) Then
cookies = 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(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(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(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 UserAgent
Private m_cookies As New System.Net.CookieCollection
Private refer As String
Private hd As New HttpDriver
Public 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(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(ByVal cookies As System.Net.CookieCollection)
m_cookies = cookies
End Function
Public Function GetCookie() As System.Net.CookieCollection
Return m_cookies
End Function
End Class
Imports System.IO
Public Class UserAgent
Private m_cookies As New System.Net.CookieCollection
Private refer As String
Private hd As New HttpDriver
Public 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(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(ByVal cookies As System.Net.CookieCollection)
m_cookies = cookies
End Function
Public 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(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 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